A potato comes from the ground, an egg from a hen. But where did that Pop-tart come from? "Unprocessed, whole foods will give you the most benefits," Berman says. Processing takes out nutrients such as antioxidants and fiber. What's worse is that a lot of processed foods tend to sneak in things that aren't really necessary like extra sodium and sugar. There's nothing wrong with indulging the occasional processed food craving (sometimes a bag of potato chips is too hard to resist!). But if you're trying to shop healthier altogether, be on the lookout for products that have been minimally processed.
Young adults. Teen girls and young women usually need more calories than when they were younger, to support their growing and developing bodies. After about age 25, a woman’s resting metabolism (the number of calories her body needs to sustain itself at rest) goes down. To maintain a healthy weight after age 25, women need to gradually reduce their calories and increase their physical activity.
Over the period 2008 to 2011, the Government Accountability Office (GAO) of the United States received 6,307 reports of health problems (identified as adverse events) from use of dietary supplements containing a combination of ingredients in manufactured vitamins, minerals or other supplement products, with 92% of tested herbal supplements containing lead and 80% containing other chemical contaminants. Using undercover staff, the GAO also found that supplement retailers intentionally engaged in "unequivocal deception" to sell products advertised with baseless health claims, particularly to elderly consumers. Consumer Reports also reported unsafe levels of arsenic, cadmium, lead and mercury in several protein powder products. The Canadian Broadcasting Corporation (CBC) reported that protein spiking, i.e., the addition of amino acids to manipulate protein content analysis, was common. Many of the companies involved challenged CBC's claim.
In humans, the large intestine is host to more than 1,000 species of microorganisms, mostly bacteria, numbering in the tens of trillions. "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. 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." 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.
To assure supplements have sufficient quality, standardization, and safety for public consumption, research efforts have focused on development of reference materials for supplement manufacturing and monitoring. High-dose products have received research attention, especially for emergency situations such as vitamin A deficiency in malnutrition of children, and for women taking folate supplements to reduce the risk of breast cancer.
Foods that contain natural folic acid include orange juice, green leafy vegetables, peas, peanuts and beans. (One cup of cooked kidney beans contains 230 mcg of folic acid.) Fortified foods, such as ready-to-eat breakfast cereals, also contain a synthetic form of folic acid, which is more easily absorbed by your body than the natural form. Folic acid is now added to all enriched grain products (thiamin, riboflavin, niacin, and iron have been added to enriched grains for many years).
There are thousands of dietary supplements on the market, including 40+ essential nutrients alone and in various combinations, i.e. vitamins, minerals, trace elements and fatty acids. However, a number of other nutrients are "conditionally essential", meaning that the body normally can make these molecules, but some people do not make optimal amounts. Examples are L-carnitine, alpha-lipoic acid, the methyl donor betaine,  chondroitin sulfate, coenzyme Q10, choline, amino acids such as tyrosine or arginine, and "essential" sugars normally formed in the body. 
Substances which the FDA regulates as food are subdivided into various categories, including foods, food additives, added substances (man-made substances which are not intentionally introduced into food, but nevertheless end up in it), and dietary supplements. The specific standards which the FDA exercises differ from one category to the next. Furthermore, the FDA has been granted a variety of means by which it can address violations of the standards for a given category of substances.
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.
Specialty products may offer particular health benefits or are targeted for specific conditions. These products may consist of whole foods or may be isolated compounds from natural or synthetic sources. Examples include antioxidants, probiotics (supplements containing friendly bacteria for the digestive tract), digestive enzymes, shark cartilage, or other animal products, or chemical extracts such as the hormone DHEA (dehydroepiandrosterone) and coenzyme Q10, an antioxidant.