In humans, the large intestine is host to more than 1,000 species of microorganisms, mostly bacteria, numbering in the tens of trillions.[59] "Probiotic" in the context of dietary supplements is the theory that by orally consuming specific live bacteria (or yeast) species, it is possible to influence the large intestine microbiota, with consequent health benefits. Although there are numerous claimed benefits of using probiotic supplements, such as maintaining gastrointestinal health, in part by lowering risk of and severity of constipation or diarrhea, and improving immune health, including lower risk of and severity of acute upper respiratory tract infections, i.e., the common cold, such claims are not all supported by sufficient clinical evidence.[60][61][62] A review based on interviews with dozens of experts in microbiome research expressed concern about "...how biomedical research is co-opted by commercial entities that place profit over health."[62] The concern is timely, as through 2021, probiotic supplements are expected to be the fastest growing segment of the dietary supplement market worldwide, while at the same time, the global health benefits market for probiotic-containing yogurt (a food, not a dietary supplement) is declining.[63][64]


Make half your plate fruits and vegetables: Choose red, orange, and dark-green vegetables like tomatoes, sweet potatoes, and broccoli, along with other vegetables for your meals. Add fruit to meals as part of main or side dishes or as dessert. The more colorful you make your plate, the more likely you are to get the vitamins, minerals, and fiber your body needs to be healthy.
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.
Overall diet is an important first consideration for those considering nutritional supplementation. Healthy dietary habits can help optimize nutrition and the absorption of supplements, and nutritional supplements cannot substitute for a diet that is not nutritionally balanced in the first place. Supplements are best used moderately to supply any extra nutritional requirements. Sound diets contain a variety of wholesome foods. At least five servings per day of fruits and vegetables are recommended, as well as the inclusion of whole grains in the diet. Variety in the diet is important to provide a full range of vitamins and minerals. Overeating inhibits digestion and absorption of nutrients, while regular exercise contributes to sound nutrition, by improving metabolism and digestion. Drinking plenty of clean water prevents dehydration, improves digestion, and helps the body flush out impurities.
The U.S. Food and Drug Administration does not regulate herbs and other dietary supplements in the same way it does prescription and non-prescription drugs. Unlike pharmaceutical manufacturers, who must prove a drug's safety and effectiveness prior to putting it on the market, supplement manufacturers are not required to prove the safety and effectiveness of a supplement before it is made available to consumers. (The Dietary Supplement Health and Education Act has exempted supplement manufacturers from these regulations). 
Vitamins and minerals are most easily digested with food. Fat-soluble vitamins should be taken with food that contains fat. Vitamins tend to work synergistically, meaning that they work together in order to be effective. For instance, vitamin E requires some of the B-complex vitamins and the minerals selenium and zinc for most effective absorption. Some minerals may not be absorbed or may inhibit each other when taken in improper ratios. Generally, a high quality, broad-spectrum vitamin and mineral supplement will be formulated to prevent unfavorable interactions.
Herbal supplements are added to the diet for both nutritional and medicinal purposes. Herbs have been used for centuries in many traditional medicine systems, and as sources of phytochemicals, or substances found in plants that have notable effects in the body. Chinese medicine and Ayurvedic medicine from India, two of the world's oldest healing systems, use hundreds of herbal medications. Naturopathy and homeopathy, two other systems of natural healing, also rely on herbal preparations as their main sources of medication. The medicinal effects of herbs are getting scientific validation; about one-fourth of all pharmaceuticals have been derived directly from plant sources, including aspirin (found in willow bark), codeine (from poppy seeds), paclitaxel (Taxol), a patented drug for ovarian and breast cancer (from the Pacific Yew tree), and many others.
A well-balanced diet, comprised of a variety of foods, adequately meets women’s needs for vitamins, minerals and energy. For good health, women need to pay special attention to calcium, iron and folate (folic acid) intake. A healthy diet also should minimize the intake of fat and sugar. Diets high in saturated or trans fat can promote high levels of blood cholesterol and increase risk for heart disease. A diet that includes high sugar provides empty calories, or calories that do not provide any nutritional value and often times replace more nutritious food selections.
"Often the enthusiasm for these vitamins and supplements outpaces the evidence. And when the rigorous evidence is available from randomized controlled trials, often the results are at odds with the findings of the observational studies," explains Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital, professor of medicine at Harvard Medical School, and principal investigator of a large randomized trial known as VITAL (Vitamin D and Omega-3 Trial).
The recommended daily intake for vitamin E is 15 mg. Don't take more than 1,000 mg of alpha-tocopherol per day. This amount is equivalent to approximately 1,500 IU of "d-alpha-tocopherol," sometimes labeled as "natural source" vitamin E, or 1,100 IU of "dl-alpha-tocopherol," a synthetic form of vitamin E. Consuming more than this could increase your risk of bleeding because vitamin E can act as an anticoagulant (blood thinner).
Proteins are chains of amino acids. Nine of these proteinogenic amino acids are considered essential for humans because they cannot be produced from other compounds by the human body and so must be taken in as food. Recommended intakes, expressed as milligrams per kilogram of body weight per day, have been established.[26] Other amino acids may be conditionally essential for certain ages or medical conditions. Amino acids, individually and in combinations, are sold as dietary supplements. The claim for supplementing with the branched chain amino acids leucine, valine and isoleucine is for stimulating muscle protein synthesis. A review of the literature concluded this claim was unwarranted.[36] In elderly people, supplementation with just leucine resulted in a modest (0.99 kg) increase in lean body mass.[37] The non-essential amino acid arginine, consumed in sufficient amounts, is thought to act as a donor for the synthesis of nitric oxide, a vasodilator. A review confirmed blood pressure lowering.[38] Taurine, a popular dietary supplement ingredient with claims made for sports performance, is technically not an amino acid. It is synthesized in the body from the amino acid cysteine.[39]
An optimum intake of all nutrients is difficult to achieve even for those who eat almost exclusively an excellent diet of nutrient dense foods, such as meat and innards, fish, shellfish, fowl, eggs, nuts, mushrooms, and vegetables, berries and nutritious fruits. Some nutrients such as folic acid or carotenoids in vegetables are absorbed better from processed than unprocessed foods. Although vegetables are often considered to be a good source of vitamins, for example vitamin A from carrots, vitamin A is only found in animal products such as liver, egg yolk, fish cod and cod liver oil. Although eating raw vegetables is helpful for several reasons (vitamin C, fiber, microbiota), carotenoids (alpha/beta-carotene, lutein, lycopene) in vegetables are less well absorbed from raw than cooked food and better absorbed in the presence of added fat. [38,39]. Nutrients in vegetables are better absorbed when finely chewed, graded, or mashed [38], and cooking and grinding meat reduces the energy required to digest it [40] and increases nutrient absorption [41].

A dietary supplement is a manufactured product intended to supplement the diet when taken by mouth as a pill, capsule, tablet, or liquid.[2] A supplement can provide nutrients either extracted from food sources or synthetic, individually or in combination, in order to increase the quantity of their consumption. The class of nutrient compounds includes vitamins, minerals, fiber, fatty acids and amino acids. Dietary supplements can also contain substances that have not been confirmed as being essential to life, but are marketed as having a beneficial biological effect, such as plant pigments or polyphenols. Animals can also be a source of supplement ingredients, as for example collagen from chickens or fish. These are also sold individually and in combination, and may be combined with nutrient ingredients. In the United States and Canada, dietary supplements are considered a subset of foods, and are regulated accordingly. The European Commission has also established harmonized rules to help insure that food supplements are safe and properly labeled.[3] Among other countries, the definition of dietary supplements may vary as drugs or other classes of ingredients used in supplement products.

"Studies show that omega-3 fatty acids are cardio-protective and the basis for the AHA recommendation to consume fatty fish twice weekly," she says. "But the studies do not show that popping a supplement can have the same benefit in healthy individuals." She adds, "There is also a misperception that fish oils can lower cholesterol, but this is not true."
Nutritional supplements may be designed to provide specialized support for athletes. Some of these consist of high-protein products, such as amino acid supplements, while other products contain nutrients that support metabolism, energy, and athletic performance and recovery. People engaging in intense athletic activity may have increased needs for water-soluble vitamins, antioxidants, and certain minerals, including chromium. Sports drinks contain blends of electrolytes (salts) that the body loses during exertion and sweating, as well as vitamins, minerals, and performance-supporting herbs.
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