More and more well done studies are being published that evaluate the true benefit of vitamins. The best studies are random, double-blind trials that use enough subjects over a long time.
Here is the latest roundup:
Vitamin E - No benefit for preventing cancer, including colon, esophageal, gastric, pancreatic or liver. No benefit for preventing cardiovascular disease and people who took over 400IU's a day had a higher risk of dying from heart failure and other causes.
Vitamin E plus Selenium - No benefit for prostate cancer and maybe did more harm than good.
Beta Carotene/Vitamin A - Smokers and non smokers may had an even higher rate of lung cancer and heart disease.
Vitamin A - had a higher risk of hip fractures than women who did not take Vitamin A supplements.
Folic Acid - essential for pregnant women but did not prevent heart disease in others.
Vitamin C - didn't prevent colds but there was a reduction in colds among people who were extreme athletes or under physical stress (soldiers)
Beta carotene, Selenium, Vitamins A, C and E (Antioxidants alone or in combo)- users had a 6% higher death rate than placebo
Vitamin B - No help for heart attack or established vascular disease.
Multivitamins - No difference in infection rates or visits to doctors.
Vitamin D - numerous studies are emerging that show the "normal" ranges are too low and higher amounts of this vitamin are associated with decreases in cardiovascular, bone loss and cancer incidence.
Calcium - Improves bone health in women and men.
Gingko Biloba - doesn't prevent dementia or Alzheimer's disease.
Bottom line: Get your vitamins from food. Use your vitamin money to buy organic food. The 5-7 fruits and vegetables recommended a day have been proven in multiple excellent studies to prevent cancer, heart disease and promote longevity.
Many people argue that the vitamin studies are flawed and they keep wasting money on supplements. That is a choice, but at the very least eat real food!