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Providing perspectives on recent research into vitamins and nutritionals


Choices for Vitamin D, a Shortfall Nutrient

By Michael McBurney

After years of training and experience, I rarely admit to being a nutritionist at social events or during casual conversations such as a train, plane or bus. The reasoning is simple. When people learn someone has some expertise in nutrition, they usually: 1) express embarassment/guilt about their dietary choices or 2) have a question. The first makes me feel like a Debbie Downer conversation is about to begin. If the second situation leads to an open discussion of science and opinions on nutrition, that is interesting. However, too often people want validation of a belief or action.  

Nutrition conversations are full of nuances. Everyone accepts that healthy eating means consuming all the right foods in the right proportions to get the essential nutrients we need. But it isn’t easy. Dietary choices are highly personable. Often our decisions are grounded in emotions, convenience, and cost. Childhood and cultural experiences, taste preferences, brand preferences (or disdain), and value systems cannot be ignored.

It is necessary to worry about choices, food alone or food and supplements, as it is to ingest the nutrients your body requires. Our priority is to consume the Recommended Dietary Allowances (RDAs): the average daily nutrient intake need to meet the requirements of nearly all (97-98%) of healthy people (by age and gender).

In examining intake distributions, the 2015 Dietary Guidelines Advisory Committee (DGAC) found almost 50% of 11 vitamins and 9 minerals to find several nutrients were under consumed. The shortfall nutrients are: vitamin A, vitamin D, vitamin E, vitamin C, folate, calcium, fiber and potassium. For adolescent and premenopausal women, iron should also be included.

Missing the target 50% of the time is pretty terrible, especially when 2/3 of adults are overeating, i.e. overweight and obese. What if diseases related to overweight and obesity might be attributable to insufficient concentrations of  vitamins in circulation and tissues?

The 2015 DGAC shortfall nutrient list is pretty compelling evidence to not be critical of someone using multivitamin-mineral supplements? And even single letter supplements for that matter.

Consider vitamin D. Nationally representative data finds that foods are not very rich sources of vitamin D. People using dietary supplements  are more likely to meet their vitamin D requirement. Supplement use doesn’t mean that diet isn’t important. In fact, dietary supplement users generally have better nutrient intakes from their diet.

Vitamin D is fat soluble and can be toxic if consumed in excess. Should people avoid using vitamin D? The 2015 DGAC recognizes that “In general, it is unlikely that most supplement users, who limit themselves to 10,000 IU/day or less, will have any evidence of toxicity, but a greater risk may exist among some groups, including small children.”  (pp 19, line 712).

In a new study of 20,308 serum 25(OH)D samples obtained from Minnesotans between 2002 and 2011, Dudenkov and colleagues report that vitamin D supplementation is increasing. They measured an increase in the number of individuals with 25(OH)D3 concentrations  above 250 nmol/L (50 ng/mL), from 9 to 233 cases per 100,000.

Most importantly, the investigators did not see a corresponding increase in acute clinical toxicity in this older population (> 65y of age). The one individual exhibiting clinical toxicity had a serum 25(OH)D concentration of 364 ng/mL (910 nmol/L). That is excessive.

However, using ≤4,000 IU daily is safe. The best advice is: have your serum 25(OH)D and calcium concentrations measured and make an informed decision with respect to dietary and supplementation habits.

Main Citation

Dudenkov DV, Yawn BP, Oberhelman SS, Fischer PR, Singh RJ, Cha SS, Maxson JA, Quigg SM, Thacher TD. Changing incidence of serum 25-hydroxyvitamin D values above 50 ng/mL: A 10-year population-based study. 2015 Mayo Clin Proc doi: 10.1016/j.mayocp.2015.02.012  

Other Citations

Fulgoni VL, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: where do Americans get their nutrients? 2011 J Nutr doi: 10.3945/jn.111.142257

Bailey RL, Fulgoni VL, Keast DR, Dwyer JT. Dietary supplement use is associated with higher intakes of minerals from food sources. 2011 Am J Clin Nutr doi: 10.3945/ajcn.111.020289