Is it futile to take vitamin D supplements?

Vitamin D can prevent rickets and osteomalacia

Is vitamin D supplementation associated with lower mortality? Previous studies have found that high-dose vitamin D supplementation is not associated with a reduction in all-cause mortality; other studies have pointed out that vitamin D supplementation may be associated with a significant reduction in cancer mortality

Screenshot source: Lancet Diabetes & Endocrinology

A recent study published in the Lancet Diabetes & Endocrinology (called the "D-Health Trial") examined the association between vitamin D supplementation and all-cause mortality

What does the new study find?

In this randomized, double-blind, controlled trial, researchers included 21,315 participants over the age of 60

During the follow-up period, the researchers randomly drew blood samples from 3,943 participants, and their analysis found that the supplements did increase vitamin D levels in the body:

Participants in the placebo group had a mean serum 25-hydroxy-vitamin D ([25(OH)D]) concentration of 77 nmol/L;

Participants in the vitamin group had a mean serum 25(OH)D concentration of 115 nmol/L

Serum 25(OH)D is an intermediate product of vitamin D metabolism and a precursor for the synthesis of active 1,25-dihydroxyvitamin D[1-25(OH)2D3].

The optimal serum 25(OH)D concentration required to maintain bone health is controversial

After a median follow-up of 5.

After a per-protocol analysis, the investigators found that all participants who actually took vitamin D3 and who completed the entire study showed a trend toward, but not significant, an 18% increase in all-cause mortality (OR 1.

In a further exploratory analysis, after excluding the first 2 years of follow-up data (because the vitamin D supplementation group had a significantly higher mortality rate in the first 2 years than the placebo group, which may have affected the outcome), the researchers found that randomization to receive Participants with vitamin D3 had a 24% higher risk of cancer death than the placebo group (HR 1.

The researchers concluded that monthly administration of vitamin D3 to unscreened older adults did not reduce their all-cause mortality

Should you take vitamin D supplements?

The review article published in the journal states: "Research shows that vitamin D has a wide range of roles in physiological systems and biological responses, including the maintenance of calcium and phosphorus homeostasis, bone health, immune function, cell cycle and differentiation

Some of the reasons for the inconsistency of research results may be:

It is related to the complexity of vitamin D metabolism and may also be related to the source of vitamin D supply, such as vitamin D obtained through sun exposure and eating food, and that obtained from dietary supplements

Moreover, the impact of vitamin D status on health may also be related to the participants' overall health status, life>

In addition, the findings may be related to the participants' vitamin D concentrations at baseline and their overall status after vitamin D supplementation

The intervention dose in this study was a monthly supplement of 60,000 IU, which is equivalent to a daily supplement of 2,000 IU

The American Institute of Medicine pointed out that long-term plasma vitamin D concentrations higher than 125 nmol/L may have potential adverse reactions
.
Although the incidence of adverse events was similar in the vitamin and placebo groups, potential adverse effects that may have arisen in the study also need to be considered, such as whether long-term vitamin D supplementation would result in more people's plasma 25(OH)D concentrations exceeding 125 nmol/L
.

In conclusion, this study showed that vitamin D supplementation did not affect all-cause mortality in people with adequate vitamin D intake
.
However, participants with native 25(OH)D concentrations below 50 nmol/L were most likely to benefit from supplementation
.
In addition, longer follow-up may be required to fully study the effects of vitamin D supplementation on disease development over decades, such as mortality over the next 10 years
.

References

[1] Rachel E Neale, et al.
, (2022).
The D-Health Trial: a randomised controlled trial of the effect of vitamin D on mortality.
The lancet Diabetes & Endocrinology.
DOI: https://doi.
org/ 10.
1016/S2213-8587(21)00345-4.

[2] Inez Schoenmakers.
(2022) Vitamin D supplementation and mortality.
The lancet Diabetes & Endocrinology.
DOI: https://doi.
org/10.
1016/S2213-8587(22)00002-X

[3] Whiting SJ, et al.
, (2011) The vitamin D status of Canadians relative to the 2011 dietary reference intakes: an examination in children and adults with and without supplement use[J].
Am J Clin Nutr.