Do obese people require more vitamin D3?

In our ongoing reporting of vitamin D related news stories, a soon to be published study (watch this space) adds support for the need to consider higher vitamin D intake levels in individules with grerater body mass. Several studies have already described an inverse relationship between serum vitamin D3 and cancer risk. Furthermore, higher plasma D3 levels are associated with improved survival in prostate, breast, lung, colorectal, and ovarian cancers. Interestingly, a better vitamin D status at the time of diagnosis and treatment, adjusted for season of diagnosis, has been shown to improve survival buy several factors are involved in the regulation of vitamin D3. The most accacpted factors are known age, gender, race, dietary intake, season and sunlight exposure. However, a new regulating factor is now making the news.

Recently, the relationship between obesity and vitamin D status has been investigated suggesting decreased bioavailability of D3 from skin synthesis and dietary sources in association with obesity. In studies of obese adolescents in the United States, vitamin D deficiency has been correlated with greater weight and elevated BMI. In the healthy adolescent population the distribution of fat was found to be associated with vitamin D status with obese adolescents being found to have D3 deficiency.

The association between vitamin D and obesity assumes even greater importance in cancer, given the alleged role of both obesity and vitamin D in cancer risk and survival. Although it has been recommended that adiposity (fatness) should be considered when assessing vitamin D requirements in obese patients, current dietary recommendations do not take into account a person’s BMI and it remains unclear whether the dose of vitamin D required for repletion is related to the degree of obesity.

There are to date, no studies which indicate whether the presence of malignant disease compounds these issues. In the new study, researchers have addressed the first aspect of this question by investigating the relationship between serum D3 and BMI in a large and diverse population of cancer patients at a comprehensive cancer center. The study found that obese cancer patients (BMI >=30 kg/m2) had significantly lower levels of serum D3 as compared to non-obese patients (BMI <30 kg/m2). The message from this new work suggests that BMI should be taken into account when assessing a patient’s vitamin D status and more aggressive vitamin D supplementation should be considered in obese cancer patients.

When the paper is published we will post a link.

Related HHC blog posts

Vitamin D & Bone Health

The return of rickets in the UK

Dietary vitamin D – the low down

Vitamin D3 and chronic pain

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