Volume 191 - Issue 1
Paradoxical nutritional deficiency in overweight and obesity: the importance of nutrient density
Author: Barbara Depczynski
Med J Aust 2009; 191 (1): 44-45. || doi: 10.5694/j.1326-5377.2009.tb02680.x
Published online: 6 July 2009
Published online: 6 July 2009
To the Editor: Markovic and Natoli draw attention to the frequent presence of nutritional deficiencies in obesity.1 While the authors detail various nutrient deficiencies that may arise from a nutrient-poor diet, they do not discuss the possibility of vitamin D deficiency.
Normally the main source of vitamin D is that synthesised in skin exposed to ultraviolet B radiation. A nutrient-rich or nutrient-poor diet alone is unlikely to provide adequate vitamin D unless foods are supplemented with vitamin D. Vitamin D deficiency in obese people is prevalent, and Holick has described an inverse relationship between body mass index and 25-hydroxyvitamin D levels, with sequestration of vitamin D in body fat reducing its availability.2 Vitamin D deficiency is associated with various conditions for which obesity is a risk factor, including cancer, depression, altered glucose metabolism and cardiovascular disease.2
A prospective study would be required to determine whether vitamin D supplementation is able to modify some of these associations. Increasing vitamin D levels are associated with improved muscle strength,2 and thus vitamin D supplements may be of benefit in obese patients with reduced vitamin D levels. Furthermore, combined vitamin D and calcium supplementation may have a small beneficial role in preventing type 2 diabetes.3 Pending more evidence, it would be prudent to consider measuring 25-hydroxyvitamin D levels in obese people and correcting any deficiency. In view of the large amount of adipose tissue in obese people, it is likely that they would require higher than normal doses to achieve repletion of their vitamin D stores.
References
- Markovic TP, Natoli SJ. Paradoxical nutritional deficiency in overweight and obesity: the importance of nutrient density. Med J Aust 2009; 190: 149-151.
- Holick MF. Vitamin D deficiency. N Engl J Med 2007; 357: 266-281. 0_i1091842
- Pittas AG, Lau J, Hu FB, Dawson-Hughes B. The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. J Clin Endocrinol Metab 2007; 92: 2017-2029. 0_CBBHCHBG