In a long, excellent study of vitamin and mineral supplements–a combined total of over 170,000 people–no supplement save selenium was shown to protect against esophageal, gastric, colorectal, pancreatic, and liver cancer.
Vitamins and minerals taken inside of food are probably different. Some external supplements appear to INCREASE GI cancer risk: especially vitamin A and beta carotene. Vitamin A, in high doses can cause prenatal malformations and birth defects, and also liver toxicity. Look for a multivitamin with less than 3500 IU Vitamin A and beta carotene, combined. More recommendations are in Dr. La Puma’s private programs.
Selenium–an undervalued mineral found in rich soil is the exception. It’s also found in Brazil Nuts–you need 2 per day to get your 200 micrograms. That’s it!
Which supplements you should take depends on your own metabolism and your own medical needs. UC Davis’ excellent study of your metabolism and your genetics has a free listserv and its moderator runs a free website to learn more.