The Food and Drug Administration (FDA) defines a supplement as “a product taken by mouth that contains a 'dietary ingredient' intended to supplement the diet. The 'dietary ingredients' in these products may include: vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites.” Supplements are intended to supplement nutrients missing in your diet, not replace them.
Before and during pregnancy. You need more of certain nutrients than usual to support your health and your baby’s development. These nutrients include protein, calcium, iron, and folic acid. Many doctors recommend prenatal vitamins or a folic acid supplement during this time. Many health insurance plans also cover folic acid supplements prescribed by your doctor during pregnancy. You also need to avoid some foods, such as certain kinds of fish. Learn more about healthy eating during pregnancy in our Pregnancy section.
Having a treat now and then is a great way to make sure your healthy eating plan stays on track. Now, you might be thinking, how can eating a piece of cake or a donut help my eating habits? By not making anything completely off limits, registered dietitians explain that you're less likely to wind up feeling deprived—which means you're also less likely to find yourself in a binge-eating episode.
You should eat a healthful, well-balanced diet during pregnancy. However, you should avoid certain foods, including raw or undercooked fish, poultry and meat; raw or partially cooked eggs or foods containing raw eggs; unpasteurized juices; raw sprouts; unpasteurized milk products; and some soft cheeses (cream cheese is OK). Avoid deli meats and frankfurters unless they have been reheated to steaming hot before eating. To prevent food-borne illnesses, take the following precautions:
The U.S. Public Health Service recommends that all women of childbearing age consume 400 mcg of folic acid (a B vitamin) daily to reduce their risk of having a pregnancy affected with spina bifida or other neural-tube defects. Women who are actively trying to get pregnant should consume 600 mcg, and lactating women should consumer 500 mcg. Women of childbearing age should also take care to meet the daily requirements for calcium, fiber, iron, protein and vitamin D. Discuss supplements with a health care professional, however. Iron and vitamin D in particular can be dangerous in high amounts.
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).
"Resolving to never eat a sweet again takes a lot of effort and can create a feeling of deprivation," Patricia Bannan, M.S., R.D.N., author of Eat Right When The Time Is Right, tells SELF. "A more realistic resolution would be to create an environment in which you can consume fewer sweets without having to rely solely on your willpower." If all you have to do is walk to your pantry, you'll grab a bag and attack it. But let's say you must put on your shoes, find your keys and drive to the store. Laziness will triumph. (Yes, sometimes sloth is a good thing!)
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.
Try a lower-calorie version. Use lower-calorie ingredients or prepare food differently. For example, if your macaroni and cheese recipe uses whole milk, butter, and full-fat cheese, try remaking it with non-fat milk, less butter, light cream cheese, fresh spinach and tomatoes. Just remember to not increase your portion size. For more ideas on how to cut back on calories, see Eat More Weigh Less.
"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.)
You may have noticed on the blog that I still share sweets and breads and tasty foods like burgers and pasta. And, you’ve probably noticed that I refer to these recipes as “clean” or “healthy.” The way I do this is I’ve become very creative at making delicious foods using sneaky ingredients. Once you get started, it gets easier and easier and you find yourself being able to enjoy all the foods you love, but in a healthier form. How cool is that?
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. 
Incorporate colorful foods into every meal — some people call it eating a rainbow. From dark greens to red berries, orange bell peppers and white onions, the colors in fruits, vegetables and even proteins are associated with important vitamins and minerals. Eating a rainbow of colorful foods, especially fruits and vegetables, is a great way to get a variety of micronutrients in your diet. Take a deep dive with our Guide to Vitamins & Minerals and check out these Rainbow-Inspired Smoothies.
However, some herbal supplements may not be safe. They could contain unlisted ingredients that make you sick. Drugs that aren’t listed on the label can include, steroids or estrogens. Products may even contain toxic, or poisonous, substances. Examples include, as arsenic, mercury, lead, and pesticides. Supplements must be recalled if they are found to contain toxic ingredients.
^ 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.
If you suspect that you have had a serious reaction from a dietary supplement, let your health care provider know. He or she may report your experience to the FDA. You may also submit a report to the FDA by calling 800-FDA-1088 or completing a form online. In addition, report your reaction to the dietary supplement company by using the contact information on the product label.
If you do decide to diet, you still need to maintain good nutrition. You want to cut back on calories, not nutrients. And while you want to reduce fat, don't eliminate it entirely. Some studies suggest that older women who maintain a higher body-fat percentage are less likely to suffer from osteoporosis and other conditions associated with menopause. Fat cells also retain estrogen, which helps maintain the calcium in your bones. Younger women should be careful, too: a low body fat percentage can lead to infertility; below 17 percent may lead to missed periods, also known as amenorrhea.
Our sedate, modern lifestyle reduces the need for energy from food, which implies a lower food intake or obesity. Loren Cordain, PhD, and coworkers have estimated that hunter-gatherers had significantly higher energy needs than the typical modern office worker.  A lower energy intake generally reduces the absolute intake of all nutrients, while the need for some nutrients is not always reduced proportionally with energy intake. Overall this suggests that more exercise along with a more nutritious diet, including supplements of essential nutrients and less carbohydrates, will help to prevent obesity and maintain health.
One exception, he says, is seniors, who may need additional B-12 because as we get older, we absorb less of it. Most of us should skip the supplements and get our Bs from grains, dark green vegetables, orange juice, and enriched foods. People with certain medical conditions or who take drugs that interfere with vitamin absorption may also require supplementation.
Processing of food reduces its nutritional content, and the finished products are often based on fractions of the original foods. One example is milling grain to make white flour,  which has a lower nutritional density than whole grain flour. The reduction in nutritional value has accelerated since whole foods are now divided into pieces, for example, boneless chicken breast. When meat is injected with saline to increase the volume, the relative level of essential nutrients is reduced. In the United States, many supermarkets in low-income rural and inner city areas have a limited selection of nutrient-dense foods, compared with high-income areas. 
^ Wilson, RD; Committee, Genetics; Wilson, RD; Audibert, F; Brock, JA; Carroll, J; Cartier, L; Gagnon, A; Johnson, J. A; Langlois, S; Murphy-Kaulbeck, L; Okun, N; Pastuck, M (2015). "Pre-conception Folic Acid and Multivitamin Supplementation for the Primary and Secondary Prevention of Neural Tube Defects and Other Folic Acid-Sensitive Congenital Anomalies" (PDF). Journal of Obstetrics and Gynaecology Canada. 37 (6): 534–552. PMID 26334606.
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
Fresh, Frozen, or Canned Vegetables ― try something new. You may find that you love grilled vegetables or steamed vegetables with an herb you haven’t tried like rosemary. You can sauté (panfry) vegetables in a non-stick pan with a small amount of cooking spray. Or try frozen or canned vegetables for a quick side dish — just microwave and serve. When trying canned vegetables, look for vegetables without added salt, butter, or cream sauces. Commit to going to the produce department and trying a new vegetable each week.
Women, as we age, are also more susceptible to the breakdown of our bones, which may result in osteoporosis over time. Genetically, women have a particularly high risk of osteoporosis compared to men, so it’s recommended that women monitor their calcium intake to be sure they’re getting enough. Weight training is another great way (and my favorite!) to build bone density, which is another great reason you should hit the weights!
Some fat is an important part of your diet; fat is part of every cell. It maintains skin and hair; stores and transports fat-soluble vitamins A, D, E and K; keeps you warm; and protects your internal organs. It even helps your mental processes—not surprising given that fat comprises about 60 percent of your brain. But many women consume too much fat. The American Heart Association (AHA) recommends that you keep your total fat intake between 25 and 35 percent of your total calories.
It's a cliché, to be sure, but a balanced diet is the key to good nutrition and good health. Following that diet, however, isn't always that easy. One challenge is that women often feel too busy to eat healthfully, and it's often easier to pick up fast food than to prepare a healthy meal at home. But fast food is usually high in fat and calories and low in other nutrients, which can seriously affect your health. At the other extreme, a multimillion dollar industry is focused on telling women that being fit means being thin and that dieting is part of good nutrition.