Many supplements have mild effects with few risks. But use caution. Vitamin K, for example, will reduce the ability of blood thinners to work. Ginkgo can increase blood thinning. The herb St. John’s wort is sometimes used to ease depression, anxiety or nerve pain, but it can also speed the breakdown of many drugs—such as antidepressants and birth control pills—and make them less effective.
Omega-3 fatty acids — essential to health and happiness, reviewed by Dr. Mary James, MD. From conception to old age, every cell in our bodies needs omega-3’s. Learn how omega-3 fatty acids benefit every body system — from the brain to the heart, breast, bones, colon, skin and more, this is one nutrient that can make all the difference to our health, our happiness, and — perhaps best of all — our longevity.
SOURCES: Elaine Turner, PhD, RD, associate professor, department of Food Science and Human Nutrition, University of Florida, Gainesville. Sharon B. Spalding, MEd, CSCS, professor, physical education and health; and associate director, Virginia Women's Institute for Leadership, Mary Baldwin College Staunton, Va. American Dietetic Association web site. Institute of Medicine at the National Academies web site.
After menopause. Lower levels of estrogen after menopause raise your risk for chronic diseases such as heart disease, stroke, and diabetes, and osteoporosis, a condition that causes your bones to become weak and break easily. What you eat also affects these chronic diseases. Talk to your doctor about healthy eating plans and whether you need more calcium and vitamin D to protect your bones. Read more about how very low estrogen levels affect your health in our Menopause section. Most women also need fewer calories as they age, because of less muscle and less physical activity. Find out how many calories you need based on your level of activity.
Recent research shows that differences in the content of the selenium in the soil can cause major differences in the concentration of selenium in meat.  For instance, since the soil in Finland is poor in selenium, the authorities decided in the early 1980s to add selenate to commercial fertilizers. A survey of selenium status among 108 healthy young people showed an increase in the blood selenium level of about 50 percent after four years. 
When it comes to carbs, the more natural and whole, the better. Go for complex carbs like 100% whole-grain breads and pasta, brown rice, starchy vegetables, legumes, nuts, seeds, low-fat dairy and plenty of fruits and vegetables. Limit simple sugars from refined grains, processed snack foods, sweets and sugar-sweetened beverages. Check out our Essential Guide to Carbs.
Don't take dramatic steps alone. You need to work closely with an experienced health care professional to lose weight, particularly if you have other medical problems, plan to lose more than 15 to 20 pounds or take medication on a regular basis. An initial checkup can identify conditions that might be affected by dieting and weight loss. Make sure you find out how much experience your health care professional has dealing with nutrition. It's not always well covered in medical schools. You may want to talk to a registered dietitian before embarking on a diet.
This article is only for your information. It is not advice about your health care. You should read the product labels carefully. It is important for you to speak to your doctor or pharmacist before taking any supplement. If you are taking medications, including over-the-counter medications, you should speak to your doctor or pharmacist. If you are taking other supplements, you should speak to your doctor or pharmacist. If you have a medical condition or health problem, or if you are pregnant or nursing, you should speak to your doctor. Consult a healthcare provider immediately if you experience any reactions or side effects.
Calcium may even be harmful for men, at least in large amounts. The worry is prostate cancer, and two Harvard studies have raised the alarm. In 1998, the Health Professionals Follow-up Study found that a high consumption of calcium from food or supplements was linked to an increased risk of advanced prostate cancer. The risk was greatest in men who got more than 2,000 mg a day. More recently, the U.S. Physicians' Health Study reported that a high consumption of calcium from dairy products appeared to increase a man's risk of prostate cancer by up to 37%. A study from the Fred Hutchinson Cancer Research Center in Seattle also found a link between calcium and advanced prostate cancer.
The average woman should get 10 to 35 percent of her daily calories from protein. Protein helps prevent muscle tissue from breaking down and repairs body tissues. Sources of animal proteins include meat, fish, poultry, eggs, milk and cheese. Vegetable proteins include dried beans and peas, peanut butter, nuts, bread and cereal. (A three-ounce serving of cooked chicken contains about 21 grams of protein.)
In addition to diet, exercise and other lifestyle factors can also play an important role in bone health. Smoking and drinking too much alcohol can increase your chances of developing osteoporosis, while weight-bearing exercise (such as walking, dancing, yoga, or lifting weights) can lower your risk. Strength or resistance training—using machines, free weights, elastic bands, or your own body weight—can be especially effective in helping to prevent loss of bone mass as you age.