D-day - Summer 2009

The sun is shining so get out of the house, catch a few rays … and indulge me for a moment because I’m going to talk, briefly, about ‘vitamin’ D. Again. Just a few paragraphs (honest) – because this so-called ‘vitamin’ is one of the most exciting and rapidly developing topics in nutrition.

 

There is a good deal of evidence that hypo-vitaminosis D (common among all you English, Scottish and Irish roses) has become one of the most serious and prevalent health issues of the day. I wrote in June about lack of D being strongly implicated in an increased risk of cancer and autoimmune disease; but now it has also been convincingly tied to asthma (Bannerjee et al ’08, Brehm et al ‘09), accelerated brain ageing (Lee et al ’09), and the metabolic syndrome. It has even been suggested – by some – that low D might cause overweight.

 

I’ll start with the very common metabolic syndrome. In this precursor to type 2 diabetes, insulin resistance is raised above normal but is not yet at diabetic levels. Several studies have found a relationship between low D status and an increased risk of metabolic syndrome (ie Lu et al ‘09). Some think that low D actually causes insulin resistance, and there are at least two trials where high dose D has been shown to increase both insulin secretion (Kotsa et al ’08) and insulin sensitivity (Nagpal et al ’09). Others think that D acts indirectly (ie (Hjelmesaeth et al ’09). In either case, anyone with metabolic syndrome would do well to add D to a regime of regular physical exercise, weight loss and a plant-based, low-carb diet (Zitterman et al ’09). Forget about the current idiotic RNI; the absolute minimum dose is 20 micrograms (Nelson et al ‘09), while the optimal dose is probably closer to 100 micrograms.

 

What about the overweight story? Well, overweight people tend to have low D levels; not because they handle D differently in the bloodstream (Winters et al ’09), but because the D they make in their skin when it is exposed to sunlight is sucked up into the sub-dermal fat cells and little of it gets out into the blood. (Rodriguez-Rodriguez et al ’09).

 

Some eccentric scientists have suggested, from this circumstantial evidence, that low D levels actually cause overweight. This idea was boosted by a study given at the Endocrine Society's 91st Annual Meeting in Washington DC. Professor Shalamar Sibley of the University of Minnesota presented data showing that in a group of 38 overweight men and women on a calorie-controlled diet, those with the highest levels of ‘vitamin’ D at the start of the trial lost weight faster than those with medium levels of D, while the low-D group found it hard to lose any weight at all (Sibley ‘09).

 

There are several possible explanations for this; for example, maybe the high-D group were taking more physical exercise – they were certainly spending more time in the sunlight, and therefore out of doors. Shalamar, however, wanted to make the headlines. “Our results suggest the possibility that the addition of vitamin D to a reduced-calorie diet will lead to better weight loss,” she said.

 

She obviously didn’t know that only a year previously, Norwegian scientists at the University of Tromso had injected D into their overweight patients to see if it would help them to lose weight (Sneve et al ‘08). They found no effect; but because Norwegian medics are completely neurotic about supplements, they used such a tiny dose of D (about half the amount you make in your skin on a sunny day), that nobody would have realistically expected to see any effect. (Having said that, the D levels they achieved were comparable with those in Shalamar’s trial subjects).

 

The Minnesota and Tromso studies were a waste of time and resources, and bone-headed to boot, because D is not a weight loss hormone. Examine the pharmacology of D and it is apparent that D supplements are actually more likely to promote slight weight gain. D increases energy efficiency. It exerts a pattern of effects in the body which tends to reduce the rate at which you burn calories, and makes you slightly more likely to store them as fat (Zemel and Sun ’08). This may be why high calcium intakes, which suppress D levels (Zemel & Sun ’08), are associated with lower body weight (ie Novotny et al ‘04).

 

Don’t, however, let this stop you from going out in the sun! Our bodies are so beautifully designed and balanced that when we get into the warm sunshine our appetites tend to fade and many of us lose weight as a result. And finally, paradoxically, ‘vitamin’ D might just end up as a high-tech slimming product. High dose D injections kill fat cells (Sergeev ’09), making this a radical but potentially long-term treatment for overweight.



  References

Banerjee A, Damera G, Bhandare R, Gu S, Lopez-Boado Y, Panettieri R Jr, Tliba O. Vitamin D and glucocorticoids differentially modulate chemokine expression in human airway smooth muscle cells. Br J Pharmacol. 2008 Sep;155(1):84-92.

Brehm JM, Celedon JC, Soto-Quiros ME, Avila L, Hunninghake GM, Forno E, Laskey D, Sylvia JS, Hollis BW, Weiss ST, Litonjua AA. Serum Vitamin D Levels and Markers of Severity of Childhood Asthma in Costa Rica. American Journal of Respiratory and Critical Care Medicine Volume 179, Pages 765-771

                  

Hjelmesaeth J, Hofsø D, Aasheim ET, Jenssen T, Moan J, Hager H, Røislien J, Bollerslev J. Parathyroid hormone, but not vitamin D, is associated with the metabolic syndrome in morbidly obese women and men: a cross-sectional study. Cardiovasc Diabetol. 2009 Feb 3;8:7

 

Kotsa K, Yavropoulou MP, Anastasiou O, Yovos JG. Role of vitamin D treatment in glucose metabolism in polycystic ovary syndrome. Fertil Steril. 2008 Oct 16

 

Lee DM, Tajar A, Ulubaev A, Pendleton N, O'Neill TW et al. Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men. : Journal of Neurology, Neurosurgery and Psychiatry 
May 2009

 

Lu L, Pan A, Hu FB, Franco OH, Li H, Li X, Yang X, Chen Y, Yu Z, Lin X. Plasma 25-hydroxyvitamin D Concentration and Metabolic Syndrome among Middle-aged and Elderly Chinese. Diabetes Care June ’09.
Published online ahead of print, doi: 10.2337/dc09-0209

 

Nagpal J, Pande JN, Bhartia A. A double-blind, randomized, placebo-controlled trial of the short-term effect of vitamin D3 supplementation on insulin sensitivity in apparently healthy, middle-aged, centrally obese men. Diabet Med. 2009 Jan;26(1):19-27

 

Nelson ML, Blum JM, Hollis BW, Rosen C, Sullivan SS. Supplements of 20 ug/d Cholecalciferol Optimized Serum 25-Hydroxyvitamin D Concentrations in 80% of Premenopausal Women in Winter. Journal of Nutrition 2009, Volume 139, Pages 540-546

 

Novotny R, Daida YG, Acharya S, Grove JS, Vogt TM. Dairy intake is associated with lower body fat and soda intake with greater weight in adolescent girls. J Nutr. 2004 Aug;134(8):1905-9.

 

Rodríguez-Rodríguez E, Navia B, López-Sobaler AM, Ortega RM. Vitamin D in overweight/obese women and its relationship with dietetic and anthropometric variables. Obesity (Silver Spring). 2009 Apr;17(4):778-82.

 

Sergeev IN. 1,25-Dihydroxyvitamin D3 induces Ca2+-mediated apoptosis in adipocytes via activation of calpain and caspase-12. Biochem Biophys Res Commun. 2009 Jun 19;384(1):18-21.

 

Sibley S. Proc. Endocrine Society's 91st Annual Meeting, Washington, DC. June ‘09

 

Sneve M, Figenschau Y, Jorde R. Supplementation with cholecalciferol does not result in weight reduction in overweight and obese subjects. Eur J Endocrinol. 2008 Dec;159(6):675-84.

 

Winters SJ, Chennubhatla R, Wang C, Miller JJ. Influence of obesity on vitamin D-binding protein and 25-hydroxy vitamin D levels in African American and white women. Metabolism. 2009 Apr;58(4):438-42

 

Zemel MB, Sun X. Calcitriol and energy metabolism. Nutr Rev. 2008 Oct;66(10 Suppl 2):S139-46. Review

 

Zittermann A, Frisch S, Berthold HK, Götting C, Kuhn J, Kleesiek K, Stehle P, Koertke H, Koerfer R. Vitamin D supplementation enhances the beneficial effects of weight loss on cardiovascular disease risk markers. American Journal of Clinical Nutrition May 2009, Volume 89, Pages 1321-1327