A study of dietary supplements sold between 2007 and 2016 identified 776 that contained unlisted pharmaceutical drugs, many of which could interact with other medications and lead to hospitalization.[79] 86% of the adulterated supplements were marketed for weight loss and sexual performance, with many containing prescription erectile dysfunction medication. Muscle building supplements were contaminated with anabolic steroids, and multiple products contained antidepressants and antihistamines. Despite these findings, fewer than half of the adulterated supplements were recalled.[79]
Nutritional supplements are exactly that, supplements to a healthy, nutritious diet. One should not take nutritional supplements in the hope that they will make up for a poor diet and lack of exercise, they will not! There are some nutritional supplements including some vitamins and minerals, as well as other nutrients/cofactors that one can use in conjunction with a healthy diet to promote optimal health. For example, to consume the amount of vitamin E that has been shown to protect the body against free radical damage, one would have to consume a very significant amount of fat calories as vitamin E is found in foods that are high in fat such as vegetable oils, nuts and seeds. it makes sense to take a supplement of vitamin E rather than consuming lots of fat. The same goes for vitamin D. It's very difficult to get vitamin D in your diet as it isn't found in many foods and studies show that most people do not get enough vitamin D.
Use MyPlate (PDF – 281 KB) as a guide to build a healthy diet. Think about filling your plate with foods from the five food groups — fruits, vegetables, grains, proteins, and dairy — at each meal. Snacks can be a good way to fill in fruits and whole grains you might have missed at meals. Most of us don’t need complicated calorie counting programs or special recipes for healthy eating.
^ MacLean CH, Newberry SJ, Mojica WA, Khanna P, Issa AM, Suttorp MJ, Lim YW, Traina SB, Hilton L, Garland R, Morton SC (2006-01-25). "Effects of omega−3 fatty acids on cancer risk: a systematic review". JAMA: The Journal of the American Medical Association. 295 (4): 403–415. doi:10.1001/jama.295.4.403. hdl:10919/79706. PMID 16434631. Retrieved 2006-07-07.

(OMNS Sept 12 2018) One of the most vitamin-restrictive countries in the world is Norway. There, authorities limit potencies to only slightly higher than RDA (Recommended Dietary Allowance) levels for dietary supplements sold outside of pharmacies. The traditional reasoning is that most people receive the nutrients they need from a "balanced diet." [1] The authorities are also obsessively concerned that some vitamins and minerals are harmful in high doses. And, since an intake of water-soluble vitamins in excess of needs is excreted in the urine, Norwegian "experts" advise that taking supplements is a waste of money. Accordingly, the argument goes, the public should be protected not only from possible harm, but also from wasting money on unnecessary nutrients. The official policies on nutritional supplements vary within OECD (Organization for Economic Cooperation and Development) countries. Some are more liberal, while others are even more restrictive.

Among general reasons for the possible harmful effects of dietary supplements are: a) absorption in a short time, b) manufacturing quality and contamination, and c) enhancing both positive and negative effects at the same time.[56] The incidence of liver injury from herbal and dietary supplements is about 16–20% of all supplement products causing injury, with the occurrence growing globally over the early 21st century.[41] The most common liver injuries from weight loss and bodybuilding supplements involve hepatocellular damage with resulting jaundice, and the most common supplement ingredients attributed to these injuries are green tea catechins, anabolic steroids, and the herbal extract, aegeline.[41] Weight loss supplements have also had adverse psychiatric effects.[84]
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.