The study, published in the Archives of Internal Medicine, was carried out by researchers from the Fred Hutchison Cancer Research Center in Seattle. The authors reported that millions of women take daily multivitamins in the belief that this will prevent certain diseases.
The study included more than 160 000 women taking part in the ongoing Women's Health Initiative study. just over 40 per cent were in overlapping trials of hormone therapy, dietary interventions, and calcium and vitamin D supplements, and just under 60 per cent of them were taking part in an observational study (ie they were going about their normal day to day lives with no particular interventions, and those who took multivitamins did so from personal choice).
The Women's Health Initiative is one of the largest US prevention studies of its kind and is looking at the most common causes of death, disability and impairments to quality of life in postmenopausal women.
The researchers collected detailed data on all participants at the start of the study (baseline) and at intervals throughout the study period. The women enrolled between 1993 and 1998, and were followed for a median of 8 years in the clinical trials and 7.9 years in the observational study.
Incidence of mortality and disease were noted up to 2005, including invasive breast cancers, cancers of the colon/rectum, kidney, bladder, stomach, ovary, and lung. The researchers also noted cases of cardiovascular disease, such as myocardial infarction (heart attack), stroke, and venous thromboembolism (blood clot).
Researchers found that more than 40% of the women taking part took multivitamins. The women who took multivitamins were also more likely to have a healthy lifestyle in terms of their diet and exercise habits.
After eight years of follow up there was no difference in the risk of cardiovascular disease, common cancers and premature death among the women who took multivitamins and those who did not.
