A common question on the forum is whether we should be supplementing our diets with various vitamins and minerals in the form of pills and potions. I decided it was time to have a look at the evidence!
It seems to be fairly well accepted that vitamin D supplementation is a good idea for those of us living at high latitudes, at least during the winter months. Also, calcium supplementation for post-menopausal women in conjunction with vitamin D appears to be recommended by the docs, so I first checked out the evidence for this and found a study that aimed to examine whether there was any association between total calcium and vitamin D intake and mortality. The conclusions:
Also, it appears that vitamin D supplementation is a good idea during calorie restriction because weight loss seems to be associated with decreased calcium absorption.
Next, I looked at the issue of anti-oxidant supplementation as I had heard that a trial of antioxidants had to be stopped because of more deaths in the group receiving supplements. This review of trials of antioxidants (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) concluded:
Then there is this review of studies examining multivitamin/mineral supplementation which found:
What about fish oils/omega 3 supplementation? I found this analysis which analysed the results of 20 studies including 63030 participants and found:
So far, then, I've only found good evidence for calcium and vitamin D supplementation and evidence that multivitamins and minerals are not needed. Omega-3 fatty acids may have a small benefit.
Of course, if you have a deficiency in a particular vitamin/mineral then supplementation may be appropriate. And, certain conditions can benefit from supplementation. For example, magnesium may be of benefit for people with high blood pressure, poor sleep.
Anyone have any firm evidence to show benefit (or harm) from supplementation with other vitamin/minerals/co-factors etc?
It seems to be fairly well accepted that vitamin D supplementation is a good idea for those of us living at high latitudes, at least during the winter months. Also, calcium supplementation for post-menopausal women in conjunction with vitamin D appears to be recommended by the docs, so I first checked out the evidence for this and found a study that aimed to examine whether there was any association between total calcium and vitamin D intake and mortality. The conclusions:
Calcium supplements, up to 1000 mg/d, and increased dietary intake of calcium may be associated with reduced risk of mortality in women. We found no evidence of mortality benefit or harm associated with vitamin D intake.
Also, it appears that vitamin D supplementation is a good idea during calorie restriction because weight loss seems to be associated with decreased calcium absorption.
Next, I looked at the issue of anti-oxidant supplementation as I had heard that a trial of antioxidants had to be stopped because of more deaths in the group receiving supplements. This review of trials of antioxidants (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) concluded:
We found no evidence to support antioxidant supplements for primary or secondary prevention [of chronic diseases]. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.
Then there is this review of studies examining multivitamin/mineral supplementation which found:
Multivitamin-multimineral treatment had no effect on mortality due to vascular causes or cancer
What about fish oils/omega 3 supplementation? I found this analysis which analysed the results of 20 studies including 63030 participants and found:
They conclude that the benefits of omega-3 fatty acids are not clear-cut and are almost certainly not as great as previously believed. Another study found similar results:There was no overall effect of omega-3 fatty acids on composite cardiovascular events or on total mortality. Omega-3 fatty acids did protect against vascular death (RR=0.86; 95% CI, 0.75-0.99; P=0.03) but not coronary events (RR=0.86; 95% CI, 0.67-1.11; P=0.24). There was no effect on arrhythmia (RR=0.99; 95% CI, 0.85-1.16; P=0.92) or cerebrovascular events (RR=1.03; 95% CI, 0.92-1.16; P=0.59). Adverse events were more common in the treatment group than the placebo group (RR=1.18, 95% CI, 1.02-1.37; P=0.03), predominantly because of an excess of gastrointestinal side effects.
Overall, omega-3 PUFA supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction, or stroke based on relative and absolute measures of association
So far, then, I've only found good evidence for calcium and vitamin D supplementation and evidence that multivitamins and minerals are not needed. Omega-3 fatty acids may have a small benefit.
Of course, if you have a deficiency in a particular vitamin/mineral then supplementation may be appropriate. And, certain conditions can benefit from supplementation. For example, magnesium may be of benefit for people with high blood pressure, poor sleep.
Anyone have any firm evidence to show benefit (or harm) from supplementation with other vitamin/minerals/co-factors etc?
Sue
