Vitamin D2: Does It Really Boost Your Levels?

meta-analysis PMID: 38458370

Quick Summary: Research shows that taking vitamin D2 supplements can increase your overall vitamin D levels. This study looked at many smaller studies to see how well vitamin D2 works and found it can be effective, especially at higher doses and for certain groups of people.

Does Vitamin D2 Work? What the Research Found

This research combined the results of 33 different studies to see how well vitamin D2 (also called ergocalciferol) works. The main findings were:

Vitamin D2 increases overall vitamin D levels: Taking vitamin D2 supplements significantly raised the total amount of vitamin D in people's blood.

Dose matters: Higher doses of vitamin D2 (over 2000 IU per day) seemed to work better.

Shorter is better: The effect was more noticeable in studies that lasted 12 weeks or less.

Who benefits most: Older adults (60+) and people with low vitamin D levels at the start of the study saw the biggest boost.

A trade-off: While total vitamin D went up, levels of a specific type of vitamin D (25(OH)D3) actually went down slightly.

Study Details

Who was studied: The research looked at data from many different studies, so the people studied varied. Some were older, some had low vitamin D levels, and some took different doses of vitamin D2.

How long: The studies lasted for different lengths of time, from a few weeks to several months.

What they took: Participants took vitamin D2 supplements in various doses. Some took less than 2000 IU per day, and some took more.

What This Means For You

Vitamin D2 can help: If you're low on vitamin D, taking a D2 supplement could help raise your levels.

Talk to your doctor: Before starting any supplement, especially if you're older or have health concerns, talk to your doctor. They can help you figure out the right dose and type of vitamin D for you.

Consider your diet: Vitamin D2 is often found in fortified foods and some plant-based sources. Vitamin D3 is found in animal products.

Get tested: Ask your doctor to check your vitamin D levels to see if you need a supplement.

Study Limitations

Not all studies are the same: The research combined many studies, and they weren't all exactly the same. This can make it harder to draw firm conclusions.

Long-term effects unknown: The study didn't look at the long-term effects of taking vitamin D2.

Other factors: The study didn't always account for things like how much sun exposure people got or what they ate.

D3 vs D2: The study showed that while total vitamin D increased, a specific type of vitamin D (D3) decreased. This is something to discuss with your doctor.

Key Findings

This meta-analysis found that vitamin D2 (ergocalciferol) supplementation significantly increases total serum vitamin D concentrations (WMD: +11.47 ng/mL, 95% CI: 9.29–13.64, p < 0.001), 25(OH)D2 levels (+11.40 ng/mL, 95% CI: 4.72–18.09, p = 0.001), and 1,25(OH)D concentrations (+5.61 ng/mL, 95% CI: 0.74–10.48, p = 0.024). However, it also decreases 25(OH)D3 levels (-4.63 ng/mL, 95% CI: -6.46 to -2.81, p < 0.001). Subgroup analyses revealed greater efficacy with doses >2000 IU/day, shorter durations (≤12 weeks), older age (≥60 years), and baseline 25(OH)D <20 ng/mL.

Study Design

The study is a meta-analysis of 33 randomized controlled trial (RCT) arms, pooling data from PubMed/Medline, Web of Science, Embase, and Scopus databases up to 3 January 2023. A random-effects model was used to calculate weighted mean differences (WMD) with 95% confidence intervals. Participant demographics varied across included trials, with subgroups stratified by age, baseline vitamin D status, dosage, and intervention duration.

Dosage & Administration

Vitamin D2 doses ranged across studies, with subgroup analysis comparing ≤2000 IU/day and >2000 IU/day. Administration methods (e.g., oral, intramuscular) were not explicitly detailed in the summary, but dosing frequency and duration were factored into subgroup analyses. Trials lasted from ≤12 weeks to longer periods.

Results & Efficacy

Vitamin D2 supplementation significantly raised total vitamin D (+11.47 ng/mL), 25(OH)D2 (+11.40 ng/mL), and 1,25(OH)D (+5.61 ng/mL) levels, all with p < 0.05. However, 25(OH)D3 concentrations declined (-4.63 ng/mL, p < 0.001). Higher doses (>2000 IU/day) and shorter durations (≤12 weeks) yielded greater increases in total vitamin D (+13.82 ng/mL and +12.53 ng/mL, respectively). Participants aged ≥60 years and those with baseline 25(OH)D <20 ng/mL also showed stronger responses (WMD: +14.40 ng/mL and +11.47 ng/mL).

Limitations

The meta-analysis did not specify individual study quality assessments or potential publication bias. Heterogeneity across trials (variable dosages, populations, and durations) may affect generalizability. Long-term efficacy and safety of vitamin D2 beyond 12 weeks remain unclear. Additionally, the summary does not detail whether adjustments were made for confounding factors like sun exposure or dietary intake.

Clinical Relevance

Vitamin D2 effectively raises total vitamin D levels, particularly in older adults, those with deficiency, or when used at higher doses (>2000 IU/day) short-term. However, its reduction of 25(OH)D3—a more biologically active metabolite—suggests caution in populations where D3 is prioritized. Clinicians should consider patient-specific factors (age, baseline status, duration) and note that D2 may be preferable for vegetarians or those avoiding animal-derived D3. Monitoring serum levels during supplementation is advised to balance benefits and potential trade-offs.

Source: https://pubmed.ncbi.nlm.nih.gov/38458370/ (2024, meta-analysis).

Vitamin D2: Does It Really Boost Your Levels?