What’s Better, Vitamin D3 or Vitamin D2?

This article showed that 600 IU of vitamin D3 significantly more effective in wintertime study.

by Kristen Monaco, Contributing Writer, MedPage Today
July 06, 2017

Vitamin D₃ was more effective at raising serum total 25-hydroxyvitamin D [25(OH)D] levels in the wintertime than vitamin D₂, according to British researchers.

Biscuits and juice fortified with 15 µg (600 IU) of vitamin D₃ showed a significantly greater increase in total 25(OH)D levels among women compared those supplemented with 15 µg (600 IU) of vitamin D₂ (74% versus 34% biscuit; 75% versus 33% juice), wrote Laura Tripkovic, PhD, of the University of Surrey in England, and colleagues, in the American Journal of Clinical Nutrition.

Compared with the vitamin D₂ biscuit group, both groups saw greater absolute incremental changes in total 25(OH)D:

• Vitamin D₃ biscuit: Δ 6.1 ng/mL (15.3 nmol/L), 95% CI 3.0-9.3 (7.4-23.3), P<0.0003
• Vitamin D₃ juice: Δ 6.4 ng/mL (16.0 nmol/L), 95% CI 3.2-9.6 (8.0-23.9), P<0.0001

Similarly, compared with the vitamin D₂ juice group, both groups showed a significantly greater absolute incremental changes in total 25(OH)D:

• Vitamin D₃ biscuits: Δ 6.5 ng/mL (16.3 nmol/L), 95% CI 3.4-9.7 (8.4-24.2), P<0.0001
• Vitamin D₃ juice:Δ 6.8ng/mL (16.9 nmol/L), 95% CI 3.6-9.9 (9.0-24.8), P<0.0001

During the 12-week trial, participants in the placebo group reported a 25% drop in total 25(OH)D levels: Δ baseline to week 12: -4.5 ng/mL (-11.2 nmol/L), 95% CI -6.7 to -2.3 (-16.7 to -5.8), P<0.0001, the authors reported.

“Our findings show that vitamin D₃ is twice as effective as D₂ in raising vitamin D levels in the body, which turns current thinking about the two types of vitamin D on its head,” Tripkovic stated in a press release. “Those who consume D₃ through fish, eggs or vitamin D₃ containing supplements are twice as more likely to raise their vitamin D status than when consuming vitamin D₂ rich foods such as mushrooms, vitamin D₂ fortified bread or vitamin D₂ containing supplements, helping to improve their long term health.”

Most current guidelines, including the NIH, consider both forms for vitamin D to be equivalent. However, it wasn’t until the past 2 decades that the differences in efficacy between vitamin D₃ (cholecalciferol) and D₂ (ergocalciferol) have been suggested, Tripkovic’s group noted, adding that there is still a lack of research that has evaluated the extent of these differences at low doses.

The randomized, double-blind study, which was held during the winter to avoid interference from UV exposure, included 335 South Asian and white European women, ages 20 to 64, who resided in the U.K. All participants were randomized into one of five groups: 15 µg (600 IU) vitamin D₂ biscuit or juice, 15 µg (600 IU) vitamin D₃ biscuit or juice, or placebo.

The researchers collected data on serum 25(OH)D levels at baseline, 6-weeks, and 12-weeks via liquid chromatography-tandem mass spectrometry. Also, measures were collected on calcium, albumin, and parathyroid hormone levels at all visits.

There were no significant differences in absolute change reported between the juice and biscuit vitamin D₃ groups (Δ 0.2 ng/mL [0.6 nmol/L], 95% CI -3.0 to 3.4 [-7.4 to 8.6], P<0.34), nor between the vitamin D₂ groups (Δ 0.4 ng/mL [0.9 nmol/L], 95% CI -2.8 to 3.5 [-6.9 to 8.7], P<0.25), which the authors noted this indicates “equivalent bioavailability.”

There were also no significant interactions regarding ethnicity, although South-Asian women tended to have a slightly greater response to both type of vitamin D, which the researchers noted was most likely attributed to their lower serum levels at baseline.

“This is a very exciting discovery which will revolutionise how the health and retail sector views vitamin D,” stated co-author Susan Lanham-New, PhD, of the University of Surrey in a press release. “Vitamin D deficiency is a serious matter, but this will help people make a more informed choice about what they can eat or drink to raise their levels through their diet.”

A study limitation was “the lack of opportunity to generate dose-response data [which] would have provided valuable insight into the physiologic response to vitamin D and thus assisted in elucidating the mechanism behind the observed differences seen in the current data,” the authors noted.

Among older adults and those getting insufficient amounts of vitamin D, the American Association of Clinical Endocrinologists recommend to increase vitamin D intake from fortified foods or supplements to at least 800 to 1,000 IU daily. People who have osteoporosis or are concerned about bone health may take a vitamin D supplement of 2000 IU daily.

• Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner