In 1994, the United States Congress passed a law defining nutritional supplements, and requiring them to be labeled as dietary supplements and identified as not intended to be a substitute for certain foods. A nutritional supplement can be defined as a product intended for consumption in tablet, capsule, powder, soft gel, gel cap, or liquid form, and containing vitamin(s), mineral(s), herb(s), other botanicals, amino acids, or any combination thereof.

In the United States, manufacturers of dietary supplements are required to demonstrate safety of their products before approval is granted for commerce.[83] Despite this caution, numerous adverse effects have been reported,[72] including muscle cramps, hair loss, joint pain, liver disease, and allergic reactions, with 29% of the adverse effects resulting in hospitalization, and 20% in serious injuries or illnesses.[72] By more than five-fold, the highest incidence of health problems derived from "combination products", whereas supplements for vitamins and minerals, lipid products, and herbal products were less likely to cause adverse effects.[72]
Iron helps to create the hemoglobin that carries oxygen in your blood. It’s also important to maintaining healthy skin, hair, and nails. Due to the amount of blood lost during menstruation, women of childbearing age need more than twice the amount of iron that men do—even more during pregnancy and breastfeeding. However, many of us aren’t getting nearly enough iron in our diets, making iron deficiency anemia the most common deficiency in women.
Supplements are most likely to cause side effects or harm when people take them instead of prescribed medicines or when people take many supplements in combination. Some supplements can increase the risk of bleeding or, if a person takes them before or after surgery, they can affect the person's response to anesthesia. Dietary supplements can also interact with certain prescription drugs in ways that might cause problems. Here are just a few examples:
According to the American Heart Association, it's better to eat more complex carbohydrates (vegetables, fruits and whole grains) than simple carbohydrates found in sugars. Complex carbohydrates add more fiber, vitamins and minerals to the diet than foods high in refined sugars and flour. Foods high in complex carbohydrates are usually low in calories, saturated fat and cholesterol.
Salt, caffeine and alcohol intake may interfere with the balance of calcium in the body by affecting the absorption of calcium and increasing the amount lost in the urine. Moderate alcohol intake (one to two standard drinks per day) and moderate tea, coffee and caffeine-containing drinks (no more than six cups per day) are recommended. Avoid adding salt at the table and in cooking
A number of supplements may interact in harmful ways with prescription or over-the-counter drugs. For example, St. John's wort may alter the breakdown of many drugs including antidepressants and birth control pills. Vitamin K, ginkgo biloba, garlic, and vitamin E may interact with blood-thinners.  That's why it's essential that you consult your physician before starting a supplement regimen or making changes to your treatment regimen or prescribed medications. 
^ Fortmann, SP; Burda, BU; Senger, CA; Lin, JS; Whitlock, EP (Nov 12, 2013). "Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force". Annals of Internal Medicine. 159 (12): 824–834. doi:10.7326/0003-4819-159-12-201312170-00729. PMID 24217421.
5. Wrap unhealthy foods in tin foil. Wrap healthy foods in plastic wrap. The old saying, “out of sight, out of mind” turns out to have some truth to it. Eating isn’t just a physical event, but also an emotional one. Your mind often determines what it wants to eat based on what your eyes see. Thus, if you hide unhealthy foods by wrapping them up or tucking them away in less prominent places, then you are less likely to eat them.
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