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. 
Animal products, such as meat, fish and poultry are good and important sources of iron. Iron from plant sources are found in peas and beans, spinach and other green leafy vegetables, potatoes, and whole-grain and iron-fortified cereal products. The addition of even relatively small amounts of meat or foods containing vitamin C substantially increases the total amount of iron absorbed from the entire meal.
Magkos, F., Fraterrigo, G., Yoshino, J., Luecking, C., Kirbach, K., Kelly, S. C., … Klein, S. (2016, April 12). Effects of moderate and subsequent progressive weight loss on metabolic function and adipose tissue biology in humans with obesity. Cell Metabolism, 23(4), 591–601. Retrieved from https://www.sciencedirect.com/science/article/pii/S1550413116300535
"Creatine is one of the most popular supplements, with over 100 studies consistently showing it can work in muscle cell recovery in athletes who engage in high-intensity, short-burst activity such as sprinting or weight lifting," notes Clark. "But it does not work for endurance or recreational athletics." (She cautions anyone taking creatine to be sure they stay well hydrated to avoid cramping.)
Minerals are the exogenous chemical elements indispensable for life. Four minerals: carbon, hydrogen, oxygen, and nitrogen, are essential for life but are so ubiquitous in food and drink that these are not considered nutrients and there are no recommended intakes for these as minerals. The need for nitrogen is addressed by requirements set for protein, which is composed of nitrogen-containing amino acids. Sulfur is essential, but for humans, not identified as having a recommended intake per se. Instead, recommended intakes are identified for the sulfur-containing amino acids methionine and cysteine. There are dietary supplements which provide sulfur, such as taurine and methylsulfonylmethane.
Obviously, the best treatment plan for poor nutrition is to change your diet. Most Americans eat too little of what they need and too much of that they don't. For many women, decreasing fat and sugar consumption and increasing fruit, vegetables and grains in your diet can make a big difference. Many women also need to boost consumption of foods containing fiber, calcium and folic acid. Compare your diet to that suggested by the food pyramid and compare your nutrient intake to the suggested daily levels. Adjust accordingly, and you may be able to dramatically improve your health.
"The front is all advertising," says Michelle K. Berman, R.D., of Fairfax, Virginia. Flip it around for the real story. The more ingredients, the more likely it has visited a few processing plants where something artificial was mixed in, says Lydia Zepeda, Ph.D., professor of consumer science at the University of Wisconsin at Madison. Plus, checking the label is a great way to find out if there are unnecessary ingredients in something seemingly healthy. Because, no, bread does not need added sugar.
In the same year, the European Food Safety Authority also approved a dietary supplement health claim for calcium and vitamin D and the reduction of the risk of osteoporotic fractures by reducing bone loss. The U.S. FDA also approved Qualified Health Claims (QHCs) for various health conditions for calcium, selenium and chromium picolinate. QHCs are supported by scientific evidence, but do not meet the more rigorous “significant scientific agreement” standard required for an authorized health claim. If dietary supplement companies choose to make such a claim then the FDA stipulates the exact wording of the QHC to be used on labels and in marketing materials. The wording can be onerous: "One study suggests that selenium intake may reduce the risk of bladder cancer in women. However, one smaller study showed no reduction in risk. Based on these studies, FDA concludes that it is highly uncertain that selenium supplements reduce the risk of bladder cancer in women."
The essential nutrient minerals for humans, listed in order by weight needed to be at the Recommended Dietary Allowance or Adequate Intake are potassium, chlorine, sodium, calcium, phosphorus, magnesium, iron, zinc, manganese, copper, iodine, chromium, molybdenum, selenium and cobalt (the last as a component of vitamin B12). There are other minerals which are essential for some plants and animals, but may or may not be essential for humans, such as boron and silicon. Essential and purportedly essential minerals are marketed as dietary supplements, individually and in combination with vitamins and other minerals.
Dietary supplements are complex products. The FDA has established good manufacturing practices (GMPs) for dietary supplements to help ensure their identity, purity, strength, and composition. These GMPs are designed to prevent the inclusion of the wrong ingredient, the addition of too much or too little of an ingredient, the possibility of contamination, and the improper packaging and labeling of a product. The FDA periodically inspects facilities that manufacture dietary supplements.
Studies link high sodium intake to higher blood pressure, and evidence suggests that many people at risk for high blood pressure can reduce their risk by consuming less salt or sodium, as well as following a healthy diet. Most Americans consume more sodium than they need. The recommended amount is less than 2,300 mg per day for children and adults to age 50. The limit drops to 1,500 mg per day for those 51 and older or those of any age who are African American or have hypertension, diabetes or chronic kidney disease. You get 2,300 mg in just one teaspoon of salt. One good way to reduce your sodium intake is to eat fewer prepared and packaged foods.
Dietary supplements are any substance that you take to improve your health or wellness. This includes vitamins, minerals, and herbs. The most common form is a pill, or capsule. You also can get them in powders, drinks, and foods. These supplements are not meant to cure diseases or health conditions. An exception is if the U.S. Food and Drug Administration (FDA) has approved it for a health claim.
Scientists still have much to learn even about common vitamins. One recent study found unexpected evidence about vitamin E. Earlier research suggested that men who took vitamin E supplements might have a lower risk of developing prostate cancer. “But much to our surprise, a large NIH-funded clinical trial of more than 29,000 men found that taking supplements of vitamin E actually raised—not reduced—their risk of this disease,” says Dr. Paul M. Coates, director of NIH’s Office of Dietary Supplements. That’s why it’s important to conduct clinical studies of supplements to confirm their effects.
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.