Active Low-Carber Forums - View Single Post - The Great Vitamin D Experiment; Ongoing II

From Dr Briffa's blog:

Quote:

Skin Cancer Foundation recognises value of vitamin D but still advises us to keep out of the sun

Posted By Dr John Briffa On June 17, 2009

I was interested to read yesterday a report regarding a recommendation coming out of the Skin Cancer Foundation in the USA. The Foundation has recommended that adults increase their intake of vitamin D from 400 IU (the recommended daily amount) to 1000 IU. This is good news, I think, because there’s abundant and continuing to amass evidence that vitamin D insufficiency and deficiency is common. And a deficiency here may well increase the risk of all manner of conditions including cardiovascular disease, bone disease, multiple sclerosis and many different forms of cancer. So, upping our intake of vitamin D could well help to protect against these conditions, and will almost certainly improve general health and wellbeing.

The Skin Cancer Foundation has made a useful recommendation, but some could argue that this organisation is, to some degree, responsible for the fact that vitamin deficiency/insufficiency is so common. The organisation recommends, not surprisingly, that we be wary of the sun, and that we all use sunscreen of at least sun protection factor (SPF) 15. From the Foundation’s website:

Since its inception in 1979, The Skin Cancer Foundation has always recommended using a sunscreen with an SPF 15 or higher as one important part of a complete sun protection regimen. Sunscreen alone is not enough, however. Read our full list of skin cancer prevention tips.

Seek the shade, especially between 10 A.M. and 4 P.M.

Do not burn.

Avoid tanning and UV tanning booths.

Use a sunscreen with an SPF of 15 or higher every day.

Apply 1 ounce (2 tablespoons) of sunscreen to your entire body 30 minutes before going outside. Reapply every two hours.

Cover up with clothing, including a broad-brimmed hat and UV-blocking sunglasses.

While there is some justification for this advice, it is obviously skin-focused. And what this sort of advice can neglect is the profound benefits sunlight exposure can have on general health. While the Skin Cancer Foundation is clearly alive to the fact that vitamin D is important, it recommends that we get this through diet and supplements. The likelihood is that these recommendations will still leave many individuals short on vitamin D, especially in the winter. See here for more information on this (bearing in mind that optimal levels of vitamin D are almost certainly going to be in excess of 40 ng/ml or 100 mmol/L).

While I am not against supplementation (I am currently taking 3000 IU of vitamin D again myself), I suspect that shying away from the sun and slavering ourselves in sunscreen will almost certainly jeopardise our chances of enjoying optimal levels of vitamin D. And the risk here is that what might be good for our skin, may have profound negative consequences for other aspects of our health.

Early in 2008 I reported on a study which weighed up the pros and cons of sun exposure regarding cancer risk. Essentially, this study estimated that each life saved as a result of reduced sunlight exposure (and reduced risk of melanoma), about 10 other lives would be lost as a result of an increased risk of other forms of cancer. The authors of this study suggested that “…increased sun exposure may lead to improved cancer prognosis and, possible, give more positive than adverse effects on health.”

On top of this, we need to remember that vitamin D and/or sunlight exposure has been linked with reduced risk of many other conditions including diabetes and cardiovascular disease. Overall, while I welcome the Skin Cancer Foundation’s call for increased vitamin D intakes, I also believe that the advice it gives regarding sun exposure is likely to be doing more harm than good.

http://www.drbriffa.com/blog/2009/0...out-of-the-sun/

Quote:

Higher vitamin D levels linked with speedier weight loss

Posted By Dr John Briffa On June 15, 2009

Recently a couple of blogs have focused on the potential role that vitamin D may play in the regulation of body weight (see here and here). One of these blogs concerns a study which found that low. Levels of vitamin D were associated with increased body weight and waist circumference. This does not mean that vitamin D deficiency or insufficiency definitely causes fatty accumulation, but this possibility exists.

As a follow-on from this, I was interested to read about a study (as yet, unpublished) which assessed the relationship between vitamin D levels and weight loss on a reduced calorie diet (you can read about it here). In this study, conducted at the University of Minnesota in the USA, 38 obese men and women were put on a reduced calorie diet (750 calories less per day than their daily requirement) for 11 weeks. The researchers looked at the relationship between vitamin D levels and extent of weight loss in the study participants.

The report linked to above states that vitamin D insufficiency was noted in many of these individuals, which possibly reflects the previous research which suggests that vitamin D deficiency might have some part to play in the development of overweight/obesity.

However, perhaps more telling that this was the finding that there was a relationship between the vitamin D levels and the extent of weight loss: the higher the vitamin D levels, the greater the weight loss. Again, this study also cannot be used to conclude that vitamin D can assist weight loss. But it is another piece of evidence which ties vitamin D to body weight control.

What is required now are intervention trials in which the effect of supplemental vitamin D on body weight is assessed, either on its own, or as part of some weight-reducing regime (e.g. diet). If such studies show that vitamin D can promote weight loss, then we will have unearthed a potentially important factor in obesity. It will also help to explain why individuals can often find themselves lighter in the summer than in the winter.

http://www.drbriffa.com/blog/2009/0...er-weight-loss/