Vitamin D 101: Follow Recommendations. Measure Status. Adjust Intake Accordingly
A new vitamin D study is garnering headlines that might cause doubt about the value of older adults using a vitamin D supplement. The findings aren’t “at odds” with national recommendations. So what should I know?
Bischoff-Ferrari and colleagues report that fall risk reduction is greatest in those achieving 25(OH)D concentrations between 21-30 ng/mL (52.5-75 nmol/L). During the 12 month study, 121 of the 200 participants (61%) had a fall. The incidence of falls was 48% in the 24,000 IU D3 group, 67% in the 60,000 IU D3 group, and 66% in the 48,000 IU D2+D3 group.
The study followed 200 community-dwelling adults (70+ y) living in Switzerland who were randomized for 1 year to one of 3 treatments: 1) 24,000 IU vitamin D3 once per month, 2) 60,000 IU vitamin D3 once per month or 3) 24,000 IU vitamin D3 plus 24,000 IU vitamin D2 once per month. There was no control (placebo) group. Primary outcomes were improving lower extremity function (measured by the Short Physical Performance Battery) and achieving blood vitamin D concentrations of at least 30 ng/mL (75 nmol/L) at 6 and 12 months.
All participants had reported a fall in the year prior to enrollment. Average initial age was 78y. At baseline, 42% had blood vitamin D concentrations ≥50 nmol/L, 58% were insufficient (< 50 nmol/L) and 13% were deficient (<25 nmol/L).
In an accompanying editorial, Cummings and colleagues question the value of vitamin D supplementation and encourage consumers to “get recommended intakes of vitamin D and other vitamins from a balanced diet with foods that naturally contain what is manufactured into supplements.” This is nonsense.
The United States Department of Agriculture maintains the National Nutrient Database. A search of release 28 on food sources of vitamin D shows the vitamin D content of foods, both D2 and D3 on per serving basis. To obtain 800 IU of vitamin D daily, a person has to eat either 24 cups of mushrooms, 30 servings of mackerel (3 oz), 37.5 servings of sockeye salmon (3 oz), 53.6 teaspoons of cod liver oil, 187.5 cups of whole milk, or 200 cups of reduced fat chocolate milk with added vitamin D. It is impossible to meet vitamin D requirements from foods alone.
As Black and colleagues wrote in the Journal of Nutrition in 2012, “It is currently unrealistic to expect the habitual Western-style diet to supply vitamin D at 10-20 µg/d “ (400-800 IU/d). The median daily intake of naturally occurring vitamin D from food is ~70 IU and the 90th percentile of 650 IU is below recommendations. In addition, > 25% of Americans 70+y old have serum 25(OH)D concentrations below the cutoff (50 nmol/L) and 70% are below 80 nmol/L.
In 2010, the Institute of Medicine increased vitamin D dietary intake recommendations to 800 IU per day for individuals 70y and older to keep serum 25(OH)D concentrations above 50 nmol/L and maintain strong bones and muscles. At this time, scientists don’t know everything about vitamin D metabolism. Serum 25(OH)D concentrations will be more stable with lower daily intakes versus high-dose monthly supplementation. There is no evidence that very high vitamin D concentrations, i.e. >100 nmol/L, are beneficial.
Looking for advice. Be smart. 1. Take a vitamin D supplement meeting the Institute of Medicine recommendations. 2. Have your serum 25(OH)D concentrations measured. 3. Increase your daily intake if your serum 25(OH)D concentration is below 50 nmol/L (20 ng/mL).
Bischoff-Ferrari HA, Dawson-Hughes B, Orav J, Staehelin HB, Meyer OW, Theiler R, Dick W, Willett WC, Egli A. Monthly high-dose vitamin D treatment for the prevention of functional decline: A randomized clinical trial. 2016 JAMA Intern Med doi: 10.1001/jamainternmed.2015.7148
Cummings SR, Kiel DP, Black DM. Vitamin D supplementation and increased risk of falling: A cautionary tale of vitamin supplements retold. 2016 JAMA Intern Med doi: 10.1001/jamainternmed.2015.7568
Yetley EA. Assessing the vitamin D status of the US population. 2008 Am J Clin Nutr 88 (2): 558S
Black LJ, Seamans KM, Cashman KD, Kiely M. An updated systematic review and meta-analysis of the efficacy of vitamin D food fortification. 2012 J Nutr doi: 10.3945/jn.112.158014
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