For instance, foods rich in vitamin E and beta-carotene are healthy and can help reduce cancer risk. However, the U.S. Preventive Services Task Force (USPSTF) and the American Academy of Family Physicians (AAFP) recommend against taking vitamin E or beta-carotene for the prevention of cardiovascular disease. People who smoke or are at risk for lung cancer also should avoid beta-carotene. It can increase their risk of lung cancer.
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.
Compared to pharmaceutical drugs, supplements of most essential nutrients are quite harmless. However, some supplements may have poor quality, or contain toxic metals such as lead or cadmium. Therefore, it is the duty of our authorities to ensure that potentially hazardous products or supplements of poor quality are not sold, and that consumers are offered fair prices in a free market. An example where the Norwegian authorities do not follow up such basic duties is that pharmacies demand more than 1,600 Norwegian Kroner (about $190) per kg of vitamin C in powder form, which would cost less than $20 with free competition and no restrictions in permitted doses or outlets.
Reduced nutritional density in many foods, combined with the use of refined "foods" like sugar, white flour and refined oils, places a greater priority on eating the most nutritious foods. Farm produce grown organically generally has higher levels of essential nutrients such as trace minerals because the soil contains higher levels of trace minerals and the produce grows slower and thus has more time to absorb nutrients from the soil. Examples of nutrient dense foods are sardines, wild salmon, shellfish, eggs, liver, kale, collards and spinach, sea plants (seaweed), garlic, blueberries, and dark chocolate. 
Manufacturers must follow certain good manufacturing practices to ensure the identity, purity, strength, and composition of their products. If the FDA finds a product to be unsafe or otherwise unfit for human consumption, it may take enforcement action to remove the product from the marketplace or work with the manufacturer to voluntarily recall the product.
"These products provide a subtle, incremental effect. You can't use a sports supplement for a week and expect to gain pounds of muscle, but if used properly, research shows they can provide a slight, not overwhelming, edge," says Andrew Shoa, PhD, vice president for regulatory affairs for the Council for Responsible Nutrition, a trade association for the dietary supplement industry.
6. Keep healthy foods in larger packages and containers, and unhealthy foods in smaller ones. Big boxes and containers tend to catch your eye more, take up space in your kitchen and pantry, and otherwise get in your way. As a result, you’re more likely to notice them and eat them. Meanwhile, smaller items can hide in your kitchen for months. (Just take a look at what you have lying around right now. It’s probably small cans and containers.)
When shopping for an herbal supplement, it's important to verify which parts of the plant were used in its production. Different components can produce different effects, some of which can harm your health. For example, research shows that while the roots of the herb kava seem to be safe, its stem peelings and leaves may contain compounds that could be toxic to the liver. Talking with your doctor or herbalist can help you determine which plant parts to look for.
Carbohydrates should provide 45%–65% of your daily calories. Most of those calories should come from the complex carbohydrates in high-fiber and unrefined foods, such as bran cereal and other whole-grain products, brown rice, beans and other legumes, and many fruits and vegetables. These carbohydrates are digested and absorbed slowly, so they raise the blood sugar gradually and don't trigger a large release of insulin. People who eat lots of these foods have higher HDL ("good") cholesterol levels and a lower risk of obesity, diabetes, and heart disease. A good amount of soluble fiber in the diet lowers LDL ("bad") cholesterol, and high-fiber diets reduce the risk of intestinal disorders ranging from constipation and diverticulosis to hemorrhoids. Some studies have shown that fiber may help reduce the risk of colon cancer. Men need more fiber than women: 38 vs. 25 grams a day before the age of 50 and 30 vs. 21 grams a day thereafter.