Inadequate levels of some vitamins can lead to chronic diseases, including cancer and heart disease. Many Americans get most of the vitamins they need from the foods they eat, but deficiencies involving even one vitamin can lead to problems.
The authors of this report in the Journal of the American Medical Association reviewed nine vitamins key to preventative care in adults (vitamins A, B6, B12, C, D, E, and K; folate; and provitamin A carotenoids) based on studies published from 1966-2002. The following is a list of health conditions and vitamins that may alter their progression:
- Osteoporosis: Vitamin D, along with calcium, has been shown to reduce bone loss and fracture risk in the elderly.
- Heart Disease: Folic acid, B6, and B12 may decrease risk for heart disease; results from studies on vitamin E preventing heart disease are less conclusive. Beta-carotene (vitamin A) may raise risk in smokers.
- Cancer: Lycopene, although technically a non-vitamin antioxidant, may be superior to vitamin E in helping prevent prostate cancer. It is found in tomatoes and tomato products. Folic acid has been shown to decrease risk for colon cancer in both genders, and breast cancer in women who drink alcohol. Beta-carotene may increase risk for lung cancer in smokers.
- Birth Defects: Folic acid appears to reduce risk for spinal birth defects in infants whose mothers take these supplements. Excessive vitamin A during pregnancy may cause negative side effects.
The elderly, vegans, and alcoholics are especially at risk for inadequate intake of some vitamins. The best natural sources for these vitamins include: Leafy greens, whole grains, and fortified grain products for folate; fish, poultry, and legumes for vitamin B6; fish, eggs, and milk for vitamin B12; citrus fruits for vitamin C; and margarine, nuts, and salad oils for vitamin E.
Fairfield KM, Fletcher RH. Vitamins for chronic disease prevention in adults: Scientific review. Journal of the American Medical Association 2002:287(23), pp. 3116-3126.