Vitamins - what is the evidence? Rohan Subasinghe

What we know already Billion dollar industry One in 3 women and 4 women take vitamins 25% older people take nutritional supplements Folate,Vit B 6 /12 deficiency related to homocysteine levels which is an independent risk factor for CVD/CHD. Higher concentrations have not been shown to reverse the disease process. Folate reduces spina bifida and other neural defects by 80% Vitamins early in life could lead to asthma and food allergies risks Beta carotene has small adverse effect on all cause CV death

Folic acid HOPE2 – 5522 with CV disease randomized to VB6+12+folate pill and placebo – lowered homocysteine by 22% but no effect on end points(MI/CVA) NORVIT – 3749 patient - similar study - trend towards increase inn fatal/non fatal MI and CVA Meta analysis of 12RCTS – folic acid does not reduce events or all cause mortality in patients with vascular disease. Low folate levels may protect against colorectal cancer

Multivitamins MAVIS – double blind RCT – Multivitamins on morbidity from infections in older people – - no effect on self reported infections, prescriptions, QOL, primary care contact Meta analysis of RCTs – litlle evidence to suggest multivitamins and minerals prevent infections in elderly people

Anti-oxidants Meta analysis – (USA) patients in 19 trials - high dosage Vit E may increase all cause mortality. Meta analysis of 14 trials – patients – Vit A,C,E and cancers – none were protective – 1)combination of A and beta carotene = 30 % incr. Risk of death. 2)combination of beta carotene and E=10% increase

Recent evidence – Dr Goran Bjelakovic and colleagues at Copenhagen University Systematic Reviewin examining the literature investigating the effects on mortality of antioxidant supplements. They looked for all primary and secondary preventative randomised controlled trials conducted in adults randomised controlled trials They looked at trials of any antioxidant supplement taken in any dose, form, combination or for any duration of time; including - vitamins A, C and E, beta- carotene and selenium compared with either an inactive placebo or no treatment.

Results and conclusion 13.1% of those taking antioxidants died 10.5% of those taking placebo or no treatment died. C Combining the studies found there was no significant effect of antioxidant supplements on mortality “no evidence to support antioxidant supplements for primary or secondary prevention [of mortality]” Vitamins A, E and beta-carotene may even increase risk of mortality.

Contd.. the researchers also found increased risk of death from any cause from 1)vitamin A (16%), 2)beta-carotene (7%) and 3)vitamin E (4%), There were no significant effects on mortality from either vitamin C or selenium

Criticisms of review Variable quality and inclusion criteria Different doses and combinations Did not examine other specific health benefits, e.g. increased energy, increased resistance to illness etc. most trials used supplement doses that were much higher than those found in a normal diet and sometimes higher than recommended daily intake levels. Trials on specific antioxidants only jsut reached statistical significance

Link to study ane/clsysrev/articles/CD007176/frame.html ane/clsysrev/articles/CD007176/frame.html