Os segredos da produção do hormônio-vitamina D – Artigo de John Cannell, MD – “Fatos não deixam de existir, apenas porque eles são ignorados.”


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“O primeiro fato que você já conhece.   A forma ativa de vitamina D é um hormônio esteróide, e o mais potente no corpo. Os hormônios esteroides funcionam por “desmascarar” o genoma. Isto é, eles habilitam a produção de proteínas e enzimas pelo seu equipamento genético, a essência da vida. Então a forma ativa de vitamina D age habilitando a expressão genética de proteínas e enzimas cruciais para a saúde em centenas de tecidos por todo o corpo. Este fato explica por que a deficiência de vitamina D é envolvida em tantas doenças diferentes.” (…)

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“O segundo fato mudou minha vida. Fez-me perguntar por quê?  O fato é o seguinte:  a maioria de nós produz mais ou menos 20.000 unidades de vitamina D após mais ou menos 20 minutos de sol de verão. (Para a maioria dos tipos de pele, um mínimo eritema por todo o corpo [vermelhidão leve] produzido pela luz de raios UVB resulta na produção de cerca de 20.000 unidades de colecalciferol.) Isto é mais ou menos 100 vezes mais vitamina D do que o governo diz que você precisa diariamente.” (…)

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O terceiro fato é mais complexo e tem a ver com a regulação singular do sistema hormonal esteróide da vitamina D. Os hormônios esteroides são moléculas fabricadas a partir do colesterol que atuam agindo sobre um receptor no genoma. Os sistemas hormonais esteroides são firmemente regulados pelo organismo. Quando os níveis estão muito baixos, o corpo fabrica mais hormônios. Quando aqueles níveis estão muito altos, o corpo produz menos. Mas não com a vitamina D.

 

Primeiramente, diferente de outros sistemas esteroides  o sistema da vitamina D necessita de ambos, colesterol e luz solar para iniciar. O corpo não tem nenhuma maneira de obter vitamina D a menos que você entre em contato com o sol ou tome suplementos. Lembre, diferentemente de todos os outros hormônios esteroides  o corpo não pode fabricar sua própria vitamina D a partir do colesterol. Ele necessita de raios de sol também.

 

Claro, até mais ou menos 300 anos atrás, os humanos sempre tiveram muitos raios solares. (…)

 

Este complexo terceiro conjunto de fatores fortemente implica numa severa deficiência difundida entre os seres humanos modernos.  Quando os sistemas de hormônio de esteróide são ligados a pleno, sem desligamento periódico, isto normalmente significa que o corpo está sempre pedindo por mais!  Uma vez que poucos de nós vivemos desnudos sob o sol, nossos sistemas de vitamina D estão secos, nossos tanques de calcidiol estão sempre com o ponteiro na reserva, nossos tecidos estão famintos por mais desse hormônio esteróide, O MAIS POTENTE DO CORPO e, talvez por isso, as doenças de nossa civilização estejam cada vez mais disseminadas.

 

É por isso toda essa estapafúrdia sobre o assunto…

 

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(…) Isso implica que os níveis de Vitamina D nos tecidos podem estar cronicamente esvaziados nos humanos modernos.  Além disso, nós não temos nenhum método fácil de saber se nós estamos depletados, uma vez que isso se tornou um estado humano padrão.

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Então o que limita a quantia de calcitriol nos tecidos? A pele.

vitamin-connection

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Trad.: José Carlos Brasil Peixoto

Você viu os recentes artigos sobre a vitamina D na Newsweek e no Boston Globe?  A manchete do artigo da Newsweek era: “Estão os americanos morrendo por falta da vitamina D?” E por que toda essa agitação sobre a vitamina D?

 

Todos nós sabemos que a vitamina D (colecalciferol) é crucial para sua saúde. Mas a vitamina D é realmente uma vitamina? Está presente nas comidas que os humanos normalmente consomem? Embora exista em algum percentual na gordura do peixe, a vitamina D não está em nossas dietas a não ser que os humanos artificialmente incrementem um produto alimentar, como o leite enriquecido com vitamina D. A natureza planejou que você a produzisse em sua pele, e não a colocasse direto em sua boca.

 

Então, seria a vitamina D realmente uma vitamina?

 

Diferentemente de qualquer outra vitamina, a vitamina D é realmente um pró-hormônio. O seu corpo é a única fonte do potente hormônio esteróide chamado calcitriol. Como isso naturalmente acontece? Primeiro, sua pele produz vitamina D quando a luz solar atinge uma molécula de pré-colesterol. Então seu fígado converte a vitamina D na forma de armazenamento chamado calcidiol (25-hidroxi vitamina D). O corpo armazena o calcidiol no sangue e na gordura para uso posterior.

 

(Seu médico pode medir o calcidiol com um exame de sangue para descobrir se você apresenta deficiência de vitamina D. Os níveis ideais de calcidiol [25-hidroxi vitamina D] estão entre 35-65 ng/ml [87-162 nm/L], ao longo do ano.)

Se você tiver suficiente calcidiol em seu sangue, então as “coisas realmente acontecem”. Um pouco de calcidiol vai para os rins para ajudar a manter os níveis de cálcio no sangue, mas o mais importante acontece nos seus tecidos. Os tecidos por toda parte do seu corpo convertem calcidiol em calcitriol. O calcitriol, ou vitamina D ativa, é o hormônio esteróide mais potente do corpo humano. É ativo em quantidades medidas em pico gramas ou 1/1.000.000.000.000 de um grama.

 

Como os todos os hormônios esteroides, o calcitriol funciona ligando seus genes. Isto é, em centenas de tecidos por todo o seu corpo, o calcitriol expõe seu genoma! Ele dá o sinal para seus genes produzirem centenas de enzimas e proteínas cruciais para manter a saúde e lutar contra doenças.

 

 

Obtendo Sua Porção de Vitamina D

 

Tudo isso acontece, só se você conseguir suficiente vitamina D a partir dos raios do sol ou de suplementos. Se você é um dos que evitam totalmente o sol, pesquisas recentes indicam que você precisa mais ou menos 4.000 unidades de vitamina D em um dia! Então você não vai conseguir suficiente vitamina D a partir do leite (a menos que você beba 40 copos por dia) ou de um multi-vitamínico (a menos que você ingira mais ou menos 10 tabletes por dia), aliás, nada disso é recomendado.

 

Se você não conseguir a vitamina D do modo como a Mãe Natureza pretendeu, a partir do raio do sol, você precisa tomar suplementos de vitamina D. Muitos de nós conseguimos muito mais vitamina D dos raios solares do que nós imaginamos, mas a maioria tem uma necessidade de mais ou menos 2.000 unidades extras por dia. Cada vez mais a Internet e lojas de suplementos alimentares e de saúde vendem vitamina D.

 

Tenha certeza de que a vitamina D que você compra é puro colecalciferol. Não compre uma preparação adicionada com vitamina A. Apenas puro colecalciferol.

 

Muitas das doenças de civilização moderna – câncer, doença de coração, diabete, hipertensão, doença periodental, depressão e até obesidade – estão agora claramente associados com a deficiência de vitamina D. Mas uma associação não é o mesmo que uma relação de causa e efeito. A deficiência de vitamina D causa muitos casos dessas doenças da civilização moderna? Nós apenas não sabemos. Nós precisamos dos Institutos Nacionais de Saúde para financiar mais pesquisa em vitamina D. Até agora, porém, eles recusaram.

 

Se você quiser entender a vitamina D, você precisa reconhecer três fatos que têm sido geralmente ignorado por quase todos exceto alguns cientistas da vitamina D.  Aldous Huxley uma vez disse, “Fatos não deixam de existir, apenas porque eles são ignorados.”  Dois destes fatos ignorados são questões simples e um terceiro é mais complexo.

 

 

O Hormônio Esteróide

 

O primeiro fato que você já conhece.  A forma ativa de vitamina D é um hormônio esteróide, e o mais potente no corpo. Os hormônios esteróides funcionam por “desmascarar” o genoma. Isto é, eles habilitam a produção de proteínas e enzimas pelo seu equipamento genético, a essência da vida. Então a forma ativa de vitamina D age habilitando a expressão genética de proteínas e enzimas cruciais para a saúde em centenas de tecidos por todo o corpo. Este fato explica por que a deficiência de vitamina D é envolvida em tantas doenças diferentes.

 

O segundo fato mudou minha vida. Fez-me perguntar por quê? O fato é o seguinte: A maioria de nós produz mais ou menos 20.000 unidades de vitamina D após mais ou menos 20 minutos de sol de verão. (Para a maioria dos tipos de pele, um mínimo eritema por todo o corpo [vermelhidão leve] produzido pela luz de raios UVB resulta na produção de cerca de 20.000 unidades de colecalciferol.) Isto é mais ou menos 100 vezes mais vitamina D do que o governo diz que você precisa diariamente.

 

Pergunte a si mesmo: por quê? Por que os seres humanos fariam tanta vitamina D, com tanta rapidez? Eu pensei sobre isto, estudei livros de ensino, pesquisei na literatura médica, perguntei a todos os peritos, e dediquei o resto de minha vida profissional a fazer outras pessoas a se perguntarem “por quê?” Por que nós teríamos um sistema hormonal esteróide que faz tanto substrato com tanta rapidez?

 

A única resposta que qualquer um pode apresentar é: “Provavelmente seja por uma boa razão.” A ciência não sabe por quê. Os biólogos sabem que a natureza não projeta sistemas tão complexos quanto o sistema hormonal esteróide da vitamina D sem alguma razão. A ciência médica simplesmente não sabe por que nós temos a capacidade para produzir tanta vitamina D tão depressa.

 

Se você pensar sobre isso por um tempo razoável, você também concluirá que é provavelmente para uma boa razão. Embora nós não saibamos por que, alguns cientistas têm tentado descobrir porque, e perdem o fôlego nas explosivas possíveis implicações.

 

Este segundo fato também diz a você algo sobre a condição humana normal – e o atual desvio de conduta. Antes de nós começarmos a viver em edifícios e carros, vestindo roupas protetoras contra o sol e besuntando em bloqueadores solares, nós lavrávamos e caçamos. E antes disso, nós procurávamos por alimentos, desnudos sob o sol subequatorial africano por mais de um milhão de anos.

 

Quanta vitamina D nós obtínhamos então? Muita.

 

Nós começamos a movermos para os interiores durante a revolução industrial e agora o movimento está quase completo.  Alguns de nós ficamos por dias, semanas, ou até meses sem deixar que um único raio de sol atinja nossa pele e produza vitamina D. Se nós formos ao sol, nossos dermatologistas nos repreendem.   Tanto faz se é bom ou ruim, esta forma de existência é aberrante para a espécie. A “moderna” evitação ao sol é um erro de conduta para o homo sapiens.

 

Uma vez que nós produzimos mais ou menos 20.000 unidades de vitamina D com alguns minutos de raio de sol (talvez 10.000 unidades após nossa pele ficar bronzeada), foi assim que o ser humano fez para ter muita vitamina D a cada dia, até muito recentemente. Agora, a maior parte de nós obtém muito pouco. Isto é simplesmente um desvio.

 

 

Controlando Natureza?

 

O terceiro fato é mais complexo e tem a ver com a regulação singular do sistema hormonal esteróide da vitamina D. Os hormônios esteroides são moléculas fabricadas a partir do colesterol que atuam agindo sobre um receptor no genoma. Os sistemas hormonais esteroides são firmemente regulados pelo organismo. Quando os níveis estão muito baixos, o corpo fabrica mais hormônios. Quando aqueles níveis estão muito altos, o corpo produz menos. Mas não com a vitamina D.

 

Primeiramente, diferente de outros sistemas esteroides  o sistema da vitamina D necessita de ambos, colesterol e luz solar para iniciar. O corpo não tem nenhuma maneira de obter vitamina D a menos que você entre em contato com o sol ou tome suplementos. Lembre, diferentemente de todos os outros hormônios esteroides  o corpo não pode fabricar sua própria vitamina D a partir do colesterol. Ele  necessita de raios de sol também.

 

Claro, até mais ou menos 300 anos atrás, os humanos sempre tiveram muitos raios solares.

 

Lembre, a ação real está nos tecidos.  O sistema de vitamina D autócrino (para a própria célula) e parácrino (para as células vizinhas) parecem estarem ligados a pleno o tempo todo. (Em termos científicos, a constante de Michaelis Menton nunca é alcançada plenamente até que ocorra o pleno equilíbrio das taxas de concentração dos substratos fisiológicos de ambas, a produção de calcidiol do fígado e da produção de calcitriol dos tecidos.)

 

O sistema direto de retroalimentação negativa (direct negative feedback) não parece estar operando em níveis fisiológicos para ambas as produções de calcidiol no fígado e calcitriol nos tecidos. Isso implica que os níveis nos tecidos podem estar cronicamente esvaziados nos humanos modernos. Além disso, nós não temos nenhum método fácil de saber se nós estamos depletados, uma vez que isso se tornou um estado humano padrão.

 

Se a produção de tecido de calcitriol está ligada a pleno, o tempo todo, o que previne a toxicidade da vitamina D nos humanos que vivem sob o sol?  Primeiro muito da vitamina D você produz é excretado pela bílis. O mesmo pode ser verdade para muito do calcidiol que seu fígado produz. Além disso, existem numerosos outros metabólitos da vitamina D. Então, apenas mais ou menos 1/1000 de seu calcidiol é transformado em calcitriol.  Dito isso, a produção nos tecidos de calcitriol está ainda correndo a pleno sob concentrações normais do substrato calcidiol.

 

Então o que limita a quantia de calcitriol nos tecidos? A pele.

 

Depois de você produzir mais ou menos 20.000 unidades, os raios de sol começam a destruir vitamina D na pele. Em outras palavras, a mesma luz solar que produz vitamina D é a primeira a iniciar o seu processo de degradação. A produção equivale à destruição.

 

Como a produção de calcitriol nos tecidos e a criação de calcidiol no fígado sempre funcionam abaixo de sua capacidade bioquímica, isso significa que o processo limitador das taxas do hormônio esteroide mais potente do corpo humano parece recair sobre a pele.  De certo modo, isso recai sobre seu comportamento, sua escolha em andar ao sol – ou não. Isto é biologicamente inigualável para qualquer um de todos os hormônios esteroides.]

 

Este complexo terceiro conjunto de fatores fortemente implica numa severa deficiência difundida entre os seres humanos modernos.  Quando os sistemas de hormônio de esteróide são ligados a pleno, sem desligamento periódico, isto normalmente significa que o corpo está sempre pedindo por mais!  Uma vez que poucos de nós vivemos desnudos sob o sol, nossos sistemas de vitamina D estão secos, nossos tanques de calcidiol estão sempre com o ponteiro na reserva, nossos tecidos estão famintos por mais desse hormônio esteróide, O MAIS POTENTO DO CORPO, e, talvez por isso, as doenças de nossa civilização estejam cada vez mais disseminadas.

 

É por isso toda essa estapafúrdia sobre o assunto…

 

Saiba mais sobre o assunto no site:

http://www.vitamindcouncil.org

Conheça melhor o autor:

http://www.vitamindcouncil.org/cannellBiography.shtml

Seu filho recebe Vitamina D suficiente? Does your child get enough vitamin D?

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vitaminaD2

Vitamin D is an essential nutrient that a growing child’s body needs to help absorb calcium and phosphorus, which are important for healthy bones and teeth.

Vitamin D mostly comes from summer sunlight as well as certain foods.

Not getting enough vitamin D has led to some children in the UK developing the rare bone disease rickets. Rickets was common during Victorian times but mostly disappeared in the 1940s.

Even if children get enough calcium from their diet, including through milk and yoghurt, without enough vitamin D, calcium cannot be properly absorbed.

Vitamin D also regulates cell growth, neuromuscular and immune function and reduction of inflammation.

Vitamin D from the sun

The British climate may be responsible for some vitamin D deficiency. 90% of vitamin D intake comes from exposure of the skin to sunlight. Between October and March, there’s not enough UVB radiation in autumn, winter and early spring sunlight.

The body can store up vitamin D over the summer months, but the amount of UVB radiation necessary to produce vitamin D also depends on a child’s skin colour.

Those with lighter complexions need less sun exposure than those with darker skin. Some children may have less exposure to the sun because their skin is covered for cultural reasons. Others may miss out because of having to stay indoors or in hospital due to medical conditions.

A balance is important between getting children out on the sun enough for their vitamin needs while making sure their delicate skin is protected from sun burn or over exposure.

Experts advise exposing the skin to regular, short periods of sun during the summer months, without sunscreen, which blocks UVB rays.  There is no official recommendation for time limits, but a short period unprotected in the sun can be around 10 to 15 minutes for most children. After that, the normal sun protection measures are needed. These include covering up and using sunscreen with a sun protection factor (SPF) of at least 15.

Vitamin D from food

Vitamin D occurs naturally in some foods, including oily fish and eggs, and is added to some foods such as spreads and breakfast cereal.

Breastfed babies get their vitamin D from their mother’s breast milk, so it is also important for breastfeeding women to get enough vitamin D themselves. Pregnantand breastfeeding women are advised to take a daily supplement containing 10 micrograms of vitamin D for the needs of the mother and growing baby.

Vitamin D from supplements

The Department of Health recommends supplement drops containing vitamin D for babies and children from six months to five years old.

This will give them their daily requirement of 7-8.5 micrograms of vitamin D.

Infant formula is fortified with vitamin D, so babies who have formula won’t need vitamin drops until they have less than 500ml (around a pint) of infant formula a day.
Check with your health visitor or GP if you have concerns.

If a breastfeeding mother didn’t have vitamin D supplements throughout her pregnancy, a health visitor may say the baby needs vitamin drops from one month old.

Women and children may qualify for free supplements containing vitamin D under the Healthy Start programme. Age-appropriate vitamin drops are also available from pharmacies and supermarkets

Fonte: http://www.webmd.boots.com/children/child-vitamin-d

 

Are you one of those who believe plain milk is enough for your child’s nutritional needs? Have you ever thought about your child’sVitamin D levels? These findings are an eye-opener

Mark ‘yes’ if these situations are relevant to your child:

1. Your child barely plays out in the sun.

2. Off late your child tends to get tired easily & seems listless at times.

3. Your child complains of pain in his joints without reason.

If your answers are predominantly ‘yes’, then this recent 11-city survey conducted by Ipsos Research will be an eye-opener for you. The purpose was to understand the level of awareness about Vitamin D among mothers – whether they considered it important enough for their child, the misconceptions about it and the harm that would befall the child if they are found to be Vitamin D deficient. The response from the 2000 mothers who were spoken to for the survey, threw up some compelling insights.

First the good news. General awareness levels among the mothers were high: most of them correctly mentioned sunlight as a source of Vitamin D. They were aware that lack of this vitamin would result in weak bones in children. The good news however, ended there!

More worrisome were several startling disclosures, viz:

-Only 50 per cent of the mothers were aware of the crucial nutritional link between calciumand Vitamin D.

-Only 14 per cent mothers felt their children were calcium-deficient. The majority of them believed the milk they were providing their children was enough to store up Vitamin D levels in the body.

-Their awareness about other sources of Vitamin D (fish, fish liver oils, egg yolk, fortified dairy and grain products) was also very low.

-They didn’t know that apart from weak bones, lack of Vitamin D also results in skin-related issues, tooth cavities and poor concentration levels.

-Majority said they give milk daily to their children and in addition also provide them fruits, milk food drinks (MFDs) and interesting home-made food. Most mothers preferred MFDs over plain milk and also felt the quantity of milk their child was consuming was sufficient for calcium absorption.

So what lessons and questions does this insightful survey throw up? For starters, there is an urgent need to shore up awareness levels among mothers because most of them feel that the source of Vitamin D is restricted largely to absorption of natural sunlight. The truth is that this vitamin can be and needs to be made available to children in many other ways as well, given the kind of lifestyles many of them lead. Mothers also need to be educated about the health hazards that calcium deficiency leads to, and the right quantity of milk that needs to be consumed everyday for calcium absorption in the body.

The findings of the survey should prompt you to stop, take note and become more aware. After all, it is awareness that leads to empowerment.

This is the first of a 10-part series that will focus on the importance of Vitamin D for children. Keep watching this space for more

A Consumer connect initiative

fonte: http://timesofindia.indiatimes.com/life-style/health-fitness/health/Does-your-child-get-enough-Vitamin-D/iplarticleshow/12247253.cms

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Vitamina D diminui o risco de autismo nas crianças – Autism prevalence in the United States with respect to solar UV-B doses: An ecological study

English: Autism awareness ribbon Português: Fi...

English: Autism awareness ribbon Português: Fita símbolo da conscientização a respeito do autismo (Photo credit: Wikipedia)

 

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Segundo este artigo publicado em revista de pediatria americana, o autismo estaria relacionado com falta de vitamina D.

E parte do tratamento seriam suplementos de vitamina D.

 

 

 

Source: Dermato-Endocrinologia

 

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Autism prevalence in the United States with respect to solar UV-B doses: An ecological study

 

 

 

Volume 4, Issue 4   October/November/December 2012
Keywords: 25(OH)D, African American, Asian American, autism, ecological, pregnancy, serum 25-hydroxyvitamin D, ultraviolet-B, vitamin D

 

Authors: William B. Grant and John J. Cannell

 
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Abstract: 
Evidence is mounting that vitamin D deficiency is intimately involved in autism. We report on autism prevalence by US state for those aged 6–17 y in 2010 with respect to indices of solar UV-B (UVB) doses. We calculated autism prevalence rates for white, black and Asian Americans by using total prevalence and relative populations of minors for each ethnic group by state. Analyses omit AK and HI (considered extreme cases), WY (no data), along with AZ and ND for black Americans (low numbers) and DC, ME, MT, ND and SD for Asian Americans (low numbers). For white Americans, the regression coefficient for solar UVB doses and autism prevalence ranged from -0.52 in January to -0.57 in October. For black Americans, the regression coefficient for latitude was 0.61, whereas those for solar UVB ranged from -0.55 to -0.61. For Asian Americans, the values for solar UVB ranged from -0.28 to -0.38. The inverse correlation between solar UVB and autism prevalence is similar to that for many types of cancer in the US. The journal literature indicates that adverse effects on fetal brain development during pregnancy due to vitamin D deficiency can explain these findings. However, we cannot rule out a role of vitamin D deficiency in early life. These results add to the evidence that vitamin D deficiency may be an important risk factor for autism and suggest that pregnant women and autistic individuals raise their serum 25-hydroxyvitamin D concentrations above 30 ng/ml.

 

Full Text

Introduction

Evidence is mounting that vitamin D deficiency is a risk factor for autism. Cannell1 [2008] first proposed and later extended2 [2010] the UV-B (UVB)-vitamin D-autism hypothesis. Kinney and colleagues3 reviewed the autism and vitamin D connection and suggested that “Vitamin D plays important roles in repairing DNA damage and protecting against oxidative stress—a key cause of DNA damage.” Mostafa and Al-Ayadhi recently studied autistic children and found a strong correlation between better autism rating scales and higher 25(OH)D levels and between higher anti-neural antibodies and lower 25(OH)D levels.4 Kočovská and colleagues5 reviewed the evidence supporting this hypothesis and called for “urgent research” into vitamin D and autism. Despite the mounting evidence, the working hypothesis has not been accepted among autism researchers. .

A map of autism rates by state for children aged 6–17 y in the Los Angeles Times in December 20116 prompted this ecological study. The map showed highest rates in the Northeast and on the West Coast and lowest among the Southern and Plains states. The trend of high rates in the Northeast and lowest rates in the Southern states is similar to that of many types of cancer,7 which were linked to solar UVB doses for July.8,9Thus, we thought that the data, when analyzed in greater detail, might show an inverse correlation between solar UVB doses and prevalence of autism.

 

Results

Table 1 gives the regression results for solar UVB doses for several different months as well as latitude. For white and Asian Americans, the regression fits for UVB in March, July and October were similar and stronger than those for UVB in January or latitude. However, for black Americans, the results for latitude were similar to those for UVB. The regression fits for black Americans were slightly stronger than for white Americans.
Table 1. Regression results, autism aged 6–17 y in the US in 2010 by state

Race, states Factor Linear fit (r, adjusted R2p) Power law fit (r)
White Americans (AK,
HI, WY omitted)
UVB-vit D, Oct -0.57, 0.31, * 0.60
UVB-vit D Mar -0.55, 0.29, * 0.58
UVB Jul -0.55, 0.28, * 0.57
UVB-vit D, Jul -0.54, 0.28, * 0.60
UVB-vit D, Jan -0.52, 0.25, * 0.52
Latitude 0.48, 0.22, * 0.48
Black Americans (AK, AZ, HI, ND, WY omitted) Latitude × latitude 0.63, 0.38, * 0.63
Latitude 0.61, 0.36, * 0.63
UVB-vit D, Oct -0.61, 0.36, * 0.69
UVB-vit D Mar -0.59, 0.33, * 0.62
UVB Jul -0.57, 0.31, * 0.60
UVB-vit D, Jan -0.56, 0.31, * 0.65
UVB-vit D, Jul -0.55, 0.29, * 0.63
Asian Americans (AK, DC, HI, ME, MT, ND, SD, WY omitted) UVB-vit D, Jul -0.38, 0.13, 0.01 0.38
UVB Jul -0.36, 0.11, 0.02 0.35
UVB-vit D, Oct -0.32, 0.08, 0.04 0.33
UVB-vit D Mar -0.30, 0.07, 0.06 0.30
Latitude × latitude 0.29, 0.06, 0.06 0.27
Latitude 0.28, 0.05, 0.08 0.27
UVB-vit D, Jan -0.28, 0.05, 0.08 0.34

*

, p < 0.001; UVB-vit D, data for vitamin D production from UVB;12 UVB Jul, data from reference 54.
No significant correlations emerged for other possible risk-modifying factors such as air pollution, alcohol consumption, obesity, poverty, or smoking.

Figures 1–3 are scatter plots of the autism prevalence data with respect to solar UVB doses. Figure 1 shows the results for white Americans with respect to October UVB vitamin D production with both linear and power-law fits to the data. Figure 2 does the same for black Americans. Figure 3shows the results for Asian Americans with respect to July UVB vitamin D production. The linear regression fits to the data show ratios for low to high UVB of 2.4 for white Americans, 3.6 for black Americans and 1.7 for Asian Americans. In all three cases, prevalence of autism with respect to changes in solar UVB decreases faster at lower UVB doses than at higher doses.

Figure 1. Scatter plot of autism prevalence for white Americans vs. solar UVB doses for October13 with linear and power-law fits to the data. Prevalence data are in arbitrary units. Omitted states: AK, HI and WY.

Figure 3. Same as Figure 1 but for Asian Americans. Omitted states: AK, DC, HI, ME, MT, ND, SD and WY.

Figure 2. Same as Figure 1 but for black Americans. Omitted states: AK, AZ, HI, ND and WY.

 

Discussion

The finding that, for both white and Asian Americans, solar UVB doses for March, July and October are much stronger than UVB doses in January or latitude suggests that vitamin D’s effect is associated with vitamin D production from solar UVB when doses are relatively high. This finding is similar to those for many types of cancer.8,9 Other ecological studies directly correlated multiple sclerosis prevalence rates with latitude.10,11 The latitudinal dependence in the United States is considered an index of wintertime solar UVB doses12 because summertime solar UVB doses are highly asymmetrical, being highest in the Southwest and lowest in the Northeast.13 Low serum 25(OH)D concentrations in winter are associated with infectious diseases such as influenza,14 which peaks in winter. However, for black Americans, the results for latitude are comparable to those for UVB.

If we assume that solar UVB production of vitamin D is an important factor in reducing risk of autism, an important question is how vitamin D deficiency before and during pregnancy and in early life affects risk. Reasonable evidence exists that autism is due in part to genetic factors. For example, evidence indicates that vitamin D status affects both male and female fertility,15 which could be due to potential genetic effects on the fetus. In addition, monozygotic twins are more likely to be concordant for autism than dizygotic twins.16 Good evidence also exists that vitamin D deficiency during pregnancy leads to adverse birth outcomes. Maternal metabolic conditions during pregnancy (diabetes, hypertension and obesity) are associated with increased risk of offspring diagnosed with autism by age 5 y.17 Vitamin D deficiency is a risk factor for diabetes,18and obesity is associated with lower serum 25(OH)D concentrations.19 Animal model studies have documented adverse effects on fetal brain development for vitamin D-deficient mothers.20 Although prompted by an interest in schizophrenia, Sullivan and colleagues21 associated family history of schizophrenia with increased risk of autism.

A study in Australia “found that the risk of women with vitamin D insufficiency (≤46 nmol/L) during pregnancy having a child with clinically significant language difficulties was increased close to twofold compared with women with vitamin D levels >70 nmol/L.”22 A study in the UK found that there were excess birth rates in April for several immune-mediated diseases found to be related to vitamin D deficiency in other studies, thereby providing evidence that vitamin D deficiency during fetal development is a risk factor for these diseases.23

Season of birth (or conception) affects risk of autism. In the 1980s and 1990s, excess birth rates for autism occurred around March.24,25However, Zerbo and colleagues26 associated wintertime conception with increased risk of autism. Maternal infection during pregnancy is associated with increased risk of autism,3,27 as is elevated maternal temperature. See Edwards29 for an explanation of how infection through increasing body temperature, is a risk factor for adverse birth outcomes.

Vitamin D reduces risk of both bacterial and viral infection.30 Lower respiratory infections are relatively common during pregnancy.31 Influenza infection during pregnancy is associated with increased risk of schizophrenia in offspring.32 Vitamin D may reduce the risk of influenza32,33 as well as that of other acute respiratory infections.34

A study in Denmark found significantly increased risk of epilepsy for those born to mothers who experienced elevated temperature during pregnancy associated with infections.35 Both epilepsy and autism have elevated birth rates in winter and lower birth rates in summer or fall.24,36

Although the journal literature supports the evidence for vitamin D deficiency before or during pregnancy as an important risk factor for autism, this ecological study cannot determine whether vitamin D status after birth plays a role although Mostafa and Al-Ayadhi’s recent study indicates such a connection.4 Both genetics and environment affect risk of autism.16 However, separating genetic from environmental factors is difficult.37

Since differences were found for those with different skin pigmentation, there might be some effects of solar irradiance other than vitamin D production involved in the link between solar UVB doses and prevalence of autism. A number of papers have reviewed the neuroendocrinology of the skin.3841 For example, keratinocytes stimulated by UVR can produce and secrete a number of cytokines.38 A recent study found that children with autism were “more likely to have decreased levels of both T helper-1(Th-1)-like cytokines (i.e. IFN-γ) and Th-2like cytokines (i.e. IL-4, IL-10).”42 Since darker pigmentation reduces the effect of UVR on keratinocytes, those with darker skin should produce fewer cytokines. Certainly more research is needed in this area.

UVA can increase serotonin production and reduce melatonin concentrations.43 “Low maternal plasma serotonin may be a risk factor for autism through effects on fetal brain development..”44 Those with autism may have a deficit of melatonin since supplementing them with melatonin improves sleep patterns.45 Since dark skin reduces the production of serotonin and degradation of melatonin, those with lighter skin have an decreased risk of autism and a recent review showed the opposite.46 Obviously, more work needs to be done in this area.

There is some evidence that UVR contributed to regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the inflammatory response system and that they may have systemic effects.41 Prenatal stressors should increase the risk of autism and maternal stress during pregnancy is weakly associated with raised maternal cortisol.47 Thus, more research is needed in this area.

 

Vitamin D recommendations

,

The Institute of Medicine determined that pregnant women require only 600 IU/d (15 µg/day) of vitamin D3 (recommending the same for a 300-pound professional football lineman) and opine that a serum 25(OH)D concentration of 20 ng/ml is adequate.48 In the US, serum 25(OH)D concentrations during pregnancy are already low,49,50 and black Americans have much lower serum 25(OH)D concentrations than white Americans in general.51 The optimal serum 25(OH)D concentration during pregnancy is above 30 ng/ml based on a number of observational studies. Representative studies reporting that levels above 30 ng/ml are optimal include those related to pregnancy outcomes such as bacterial vaginosis,52 birth weight,53 primary Cesarean section delivery,54 and pre-eclampsia.55 In addition, gestational 25(OH)D concentrations are associated with normal fetal brain development20,56 and levels above 30 ng/ml are associated with reduced risk of childhood neuropsychological impairments,57 and development language difficulties.58

There is also evidence that serum 25(OH)D concentrations above 40 ng/ml might be considered optimal during pregnancy since optimal production of 1,25-dihydroxyvitamin D was achieved above this value in a randomized controlled trial with pregnant women.59,60 No adverse effects on calcium metabolism or other parameters were apparent in pregnant women taking 4000 IU/d of vitamin D3.60 A recent study of 25(OH)D levels in women living a traditional life style near the equator found mean serum 25(OH)D levels of nearly 60 ng/ml in pregnancy, approximately triple that of pregnant women in more developed poleward countries who putatively live and work indoors.61

The optimum 25(OH)D levels for children with autism are unknown although Mostafa and Al-Ayadhi found a strong negative correlation between autism rating scales and 25(OH)D levels in children with autism.4 They did not report a flattening of the association with higher vitamin D levels and improved autism scores although their study was limited by both the sample size and the low number of children with higher vitamin D levels. They also found autistic children have lower 25(OH)D levels than do control children although both groups reported similar time outdoors.

Mean “natural” 25(OH)D levels (as opposed to “normal” 25(OH)D levels) are around 46 ng/ml, as recently discovered by Luxwolda et al. who studied 25(OH)D levels of hunter-gatherers in equatorial Tanzania.62 Such “natural” 25(OH)D levels were common among tanned lifeguards in Missouri.63

 

Conclusion

This ecological study finds that autism prevalence among those aged 6–17 y in 2010 was significantly inversely correlated with solar UVB doses. Taken together, these results and other findings strongly implicate vitamin D deficiency as an important risk factor for developing autism. Maternal vitamin D deficiency appears to play an important role although we cannot discount a role of vitamin D deficiency in early life. Further studies should evaluate the UVB-vitamin D-autism hypothesis in both pregnant women and children with autism.

 

Methods

WBG obtained prevalence data from the Data Accountability Center associated with the Individuals with Disabilities Education Act data. The numbers of children by state with autism in 2010 are from Part B, Child Count (https://www.ideadata.org/PartBChildCount.asp (accessed Dec 16, 2011). Data used included the number of children with autism aged 6–17 y; those aged 6–21 y; and number of Asian, black and white children aged 6–21 y with autism. The data for those aged 6–17 y were not separated by race. WBG used the data by race for those aged 6–21 y with autism to estimate the number by race of those aged 6–17 y.

The data for total population aged 6–17 y by state are from Part C, Population and Enrollment Data, Table C-4, Number of and percentage change in estimated resident population ages 6–17, by state: 2001, 2009 and 2010 (https://www.ideadata.org/PopulationData.asp#2010[accessed Dec 16, 2011]).

WBG calculated the estimated population by race and state for children aged 6–17 y, he calculated numbers of autism children for each race and state. WBG obtained racial populations by state for children aged 5–17 y in 2009 from the US. Census Bureau (http://www.census.gov/compendia/statab/cats/population/estimates_and_projections_by_age_sex_raceethnicity.html [accessed Dec 18, 2011]). The fractions for single races were as follows: white (including Hispanics), 0.760; black, 0.151; and Asian, 0.043. WBG used these values to apportion the population by state into the three racial categories to calculate autism rates by race and state.

The independent variables used in this ecological study were solar UVB doses and latitude. WBG used two sets of data for UVB doses. One was DNA-weighted surface UVB doses from the Total Ozone Mapping Spectrometer (TOMS) for noon for July 1992.64 Grant and Garland9 used these data in an ecological study of cancer mortality rates. The other data set was monthly solar UVB doses weighted for vitamin D production from TOMS, validated using ground-based measurements and averaged over the period 1980–1990 for 12:00–12:59 p.m. local time.13 Solar UVB doses in the US in summer are highly asymmetric, with levels highest in the Southwest, lowest in the Northeast. The reasons for this asymmetry include that surface elevations are higher in the West, whereas stratospheric ozone column contents are lower. In addition, the Northeast has greater aerosol loading and cloud cover. For both sets of data, WBG estimated the UVB dose for each state from the maps in an effort to weight it by each state’s population distribution. A problem with the data maps from Fioletov and colleagues is that the contours are closely spaced in the Southwest, making this graphical approach less reliable for those states.

Latitude is an index for wintertime solar UVB dose and vitamin D production because solar zenith angle is much more important in winter than is surface elevation and stratospheric ozone column content. WBG chose latitude data to be near the center of population for each state. The second-order regression with latitude yielded the best model for multiple sclerosis prevalence among veterans of World War II and the Korean War in the US10 Scientists have linked multiple sclerosis to the Epstein-Barr virus, and other diseases linked to this virus have peak rates in March.65

This report omits data for AK and HI because those states are at the extreme latitudes and were not used in other ecological studies such as those regarding solar UVB and cancer.8 No data were available for Wyoming. In addition, some states have few Asians and/or blacks with autism, yielding poor estimates of autism rates. For black Americans, analyses omitted AZ and ND. For Asian Americans, DC, ME, MT, ND and SD were also omitted.

The analyses also used data for several possible risk-modifying factors, as has been done for cancer.9 These factors included alcohol consumption, lung cancer mortality rates for females, obesity, fraction of population living below poverty level and particulate air pollution concentrations.

WBG conducted linear regression analyses with the SPSS 20.0 statistical package (IBM/SPSS, Chicago, IL) and power law regression analyses with KaleidaGraph version 4.02 (Synergy Software, Reading, PA). Graphs were prepared using KaleidaGraph.

 

Disclosure of Potential Conflicts of Interest

W.B.G. receives funding from the UV Foundation (McLean, VA), Bio-Tech Pharmacal (Fayetteville, AR), the Vitamin D Council (San Luis Obispo, CA), the Vitamin D Society (Canada) and the Sunlight Research Forum (Veldhoven). J.J.C. is president of the Vitamin D Council and receives remuneration from Purity Products, Inc.

 

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60. Hollis BW, Johnson D, Hulsey TC, Ebeling M, Wagner CL. Vitamin D supplementation during pregnancy: double-blind, randomized clinical trial of safety and effectiveness. J Bone Miner Res 2011; 26:2341-57; PMID: 21706518; DOI: 10.1002/jbmr.463.
61. Luxwolda MF, Kuipers RS, Kema IP, van der Veer E, Dijck-Brouwer DA, Muskiet FA. Vitamin D status indicators in indigenous populations in East Africa. Eur J Nutr 2012; ; PMID: 22878781; DOI: 10.1007/s00394-012-0421-6.
62. Luxwolda MF, Kuipers RS, Kema IP, Janneke Dijck-Brouwer DA, Muskiet FA. Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l. Br J Nutr 2012; 108:1557-61; PMID: 22264449; DOI: 10.1017/S0007114511007161.
63. Haddad JG, Chyu KJ. Competitive protein-binding radioassay for 25-hydroxycholecalciferol. J Clin Endocrinol Metab 1971; 33:992-5; PMID: 4332615; DOI: 10.1210/jcem-33-6-992.
64. Leffell DJ, Brash DE. Sunlight and skin cancer. Sci Am 1996; 275:52-3, 56-9; PMID: 8658110; DOI: 10.1038/scientificamerican0796-52.
65. Douglas AS, Brown T, Reid D. Infectious mononucleosis and Hodgkin’s disease–a similar seasonality. Leuk Lymphoma 1996; 23:323-31; PMID: 9031113; DOI: 10.3109/10428199609054835.

 

 

 

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Estudo destaca a vitamina D como forte aliada contra várias doenças

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Baixos níveis da vitamina no organismo já foram associados a uma sucessão de problemas de saúde, desde doenças cardiovasculares até doenças neurológicas

“A vitamina — que na verdade é um hormônio — pode ser encontrada no leite, no salmão, sardinha, óleo de fígado de peixe, cogumelo, ovos e alguns cereais que são fortificados com essa vitamina. Entretanto, uma maneira boa de manter níveis adequados do hormônio é tomar sol de 10 a 15 minutos — nos bons horários ou somente até começar leve vermelhidão na pele exposta —, duas vezes ao dia, pois a luz solar é uma das principais fontes de absorção do nutriente. O responsável por esse estímulo é ninguém menos do que o raio UVB. Em outras palavras, apesar de perigoso em doses exageradas, o sol é necessário à saúde.”

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Vitamina pode ser encontrada em alimentos como leite, salmão, sardinha, óleo de fígado de peixe, cogumelo e ovos

 

Um estudo realizado por cientistas da Universidade de Oxford, na Inglaterra, recebeu destaque na mídia nacional e internacional recentemente. Eles sequenciaram o código genético humano para averiguar quais regiões do DNA apresentavam receptores para as vitaminas. Receptores são uma espécie de fechadura química só aberta por chaves compatíveis — nesse caso, a vitamina D —, para liberar o acesso e a ação do composto à estrutura a qual pertencem.

O time de Oxford descobriu nada menos do que 2.776 pontos de ligação com receptores desta vitamina, cujo baixos níveis no organismo já foram associados a uma sucessão de problemas de saúde, desde doenças cardiovasculares até doenças neurológicas.

— A carência afeta mais de 200 processos no organismo, ou seja, a sua falta prejudica desde o humor até a pressão arterial e o risco de infarto — alerta Ícaro Alves Alcântara, médico especialista em homeopatia.

A vitamina — que na verdade é um hormônio — pode ser encontrada no leite, no salmão, sardinha, óleo de fígado de peixe, cogumelo, ovos e alguns cereais que são fortificados com essa vitamina. Entretanto, uma maneira boa de manter níveis adequados do hormônio é tomar sol de 10 a 15 minutos — nos bons horários ou somente até começar leve vermelhidão na pele exposta —, duas vezes ao dia, pois a luz solar é uma das principais fontes de absorção do nutriente. O responsável por esse estímulo é ninguém menos do que o raio UVB. Em outras palavras, apesar de perigoso em doses exageradas, o sol é necessário à saúde.

— Estima-se que a vitamina D esteja faltando em mais de 70% da população, sobretudo no inverno, com a diminuição dos raios UVB — diz Alcântara.

O sistema imunológico é outro beneficiado, como explica a farmacêutica Rogy Tokarski:

— A quantidade certa da vitamina permite que o corpo se defenda melhor de doenças como a gripe.

Esperança contra a esclerose

A substância tem sido vista como uma esperança também para pacientes de esclerose múltipla, doença autoimune que acomete células nervosas e leva à perda gradual dos movimentos. Já se sabe que o seu avanço é mais rápido em quem convive com níveis baixos da substância, como documentou um estudo da Universidade de Maas­tricht, na Holanda, após acompanhar 267 pessoas com a doença.

Outra pesquisa realizada pelo Centro Médico da Universidade de Rochester, nos Estados Unidos, sugere que a falta de Vitamina D pode prejudicar o tratamento de pacientes com câncer de mama. Os cientistas descobriram que 70% das 200 voluntárias, cujos resultados do tratamento se apresentavam comprometidos, tinham baixo índice da vitamina no sangue.

 

VIDA DO CLICRBS

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Risco de câncer de pele vs importância da vitamina D – Risk of skin cancer vs importance of vitamin D

Para compensar qualquer perda de produção de vitamina D em razão de evitar o Sol e as suas medidas protetoras (filtro solar impede a produção de vitamina D), os suplementos de Vitamina D poderiam ser disponibilizados prontamente e os países poderiam considerar fortalecer alimentos com vitamina D3.

(…) To compensate for any vitamin D production lost due to sun avoidance and protection measures, vitamin D supplements could be made more readily available and countries could consider fortifying food with vitamin D3.(…)

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Two recent papers in the British Journal of Dermatology made recommendations on how to reduce skin cancer incidence rates in Europe.1,2 While reducing skin cancer incidence rates is a worthwhile health measure, policies aimed doing so should not compromise overall health.

Ultraviolet (UV) irradiance is the primary risk factor for skin cancer. However, solar UVB is also the most important source of vitamin D for most people, and vitamin D has many health benefits. Thus, measures aimed at reducing skin cancer incidence should be designed in a manner not to reduce vitamin D production from solar UVB irradiance or recommend vitamin D supplements to compensate for reduced vitamin D production from solar UVB.

Skin pigmentation changes throughout the world in response to solar UV doses, striking a balance between protection against folate destruction and the effects of free radical formation on one hand and vitamin D production on the other hand.3 Most Europeans have skin pigmentation well suited to their location due to the long history of civilization in Europe and the relative immobility compared to, say, the United States. Thus, Europeans should not be at high risk for skin cancer.

There is reasonable evidence that skin cancer is associated with better overall health outcomes, likely through higher serum 25-hydroxyvitamin D [25(OH)D] concentrations. A study in Denmark found a 10-year mortality rate ratio = 0.91 (95% CI: 0.89-0.92) for those who developed basal cell carcinoma (BCC), but an increased mortality rate ratio for those who developed squamous cell carcinoma (SCC).4 Smoking is an important risk factor for SCC but only weakly for BCC,5 as well as many adverse health outcomes, which likely explains the different findings.

An ecological study of internal cancer mortality rates with respect to nonmelanoma skin cancer mortality rate in Spain found inverse correlations for mortality rates for 15 types of cancer.6

A study of cancer incidence rates related to 54 categories of occupation using lip cancer standardized incidence ratios (SIRs) less lung cancer SIRs for men as the index of solar UVB dose found this index significantly inversely correlated with 14 types of internal cancer for men and three types of internal cancers for women.5 The evidence that solar UVB reduces the risk of many types of cancer is reviewed in a recent paper.7

There are many types of disease for which vitamin D is protective in addition to many types of cancer. Such diseases include Alzheimer’s disease, cardiovascular disease, diabetes mellitus, and respiratory infections.8,9 Based on calculations of disease outcomes with respect to serum 25(OH)D concentrations, it was estimated that mortality rates in Europe could be reduced by 15-17% and life expectancy increased by 2 years if population mean 25(OH)D concentrations were increased from 54 nmol/l to 110 nmol/l.8 Similar estimates were found for the United States.9  A conference of vitamin D experts meeting in Paris in 2009 recommended serum 25(OH)D concentrations above 75-100 nmol/l.10

Looking at Tables 3-5 in Ref. 1, it appears that outdoor hobbies contribute the most risk for BCC, SCC, and melanoma, followed by outdoor work for BCC and SCC, with sunburns and sunbed use contributing much less risk. However, as found for Nordic countries, outdoor work was very protective against many types of internal cancers for males. As for outdoor hobbies, the best advice would likely be to avoid sunburning, as outdoor hobbies are an important source of vitamin D.

To compensate for any vitamin D production lost due to sun avoidance and protection measures, vitamin D supplements could be made more readily available and countries could consider fortifying food with vitamin D3.

References

1. de Vries E, Arnold M, Altsitsiadis E, et al. Potential impact of interventions resulting in reduced exposure to ultraviolet (UV) radiation (UVA and UVB) on skin cancer incidence in four European countries, 2010-2050. Br J Dermatol. 2012; 167 Suppl 2:53–62.

2. Diepgen TL, Fartasch M, Drexler H, Schmitt J. Occupational skin cancer induced by ultraviolet radiation and its prevention. Br J Dermatol. 2012; 167 Suppl 2:76–84.

3. Jablonski NG, Chaplin G. Colloquium paper: human skin pigmentation as an adaptation to UV radiation. Proc Natl Acad Sci U S A. 2010; 107 Suppl 2:8962–8.

4. Jensen AØ, Lamberg AL, Jacobsen JB, et al. Non-melanoma skin cancer and ten-year all-cause mortality: a population-based cohort study. Acta Derm Venereol. 2010; 90:362–7.

5. Grant WB. Role of solar UV irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries. Dermatoendocrinol. 2012; 4:203–11.

6. Grant WB. An ecologic study of cancer mortality rates in Spain with respect to indices of solar UV irradiance and smoking. Int J Cancer. 2007; 120:1123–7.

7. Grant WB. Role of solar ultraviolet-B irradiance in reducing cancer risk. Anticancer Agents Med Chem. 2012 Oct 12. [Epub ahead of print]

8. Grant WB. An estimate of the global reduction in mortality rates through doubling vitamin D levels. Eur J Clin Nutr. 2011; 65:1016–26.

9. Grant WB. In defense of the sun: An estimate of changes in mortality rates in the United States if mean serum 25-hydroxyvitamin D levels were raised to 45 ng/mL by solar ultraviolet-B irradiance. Dermatoendocrinol. 2009; 1:207–14.

10. Souberbielle JC, Body JJ, Lappe JM, et al. Vitamin D and musculoskeletal health, cardiovascular disease, autoimmunity and cancer: Recommendations for clinical practice. Autoimmun Rev. 2010; 9:709-15

Fonte: http://blog.vitamindcouncil.org/2012/12/18/risk-of-skin-cancer-vs-importance-of-vitamin-d/

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