"Studies show that omega-3 fatty acids are cardio-protective and the basis for the AHA recommendation to consume fatty fish twice weekly," she says. "But the studies do not show that popping a supplement can have the same benefit in healthy individuals." She adds, "There is also a misperception that fish oils can lower cholesterol, but this is not true."
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. 
Some supplements that were found to have health benefits in observational studies turned out, with more rigorous testing, to be not only ineffective but also risky. Vitamin E, which was initially thought to protect the heart, was later discovered to increase the risk for bleeding strokes. Folic acid and other B vitamins were once believed to prevent heart disease and strokes—until later studies not only didn't confirm that benefit but actually raised concerns that high doses of these nutrients might increase cancer risk.
Overall, one should make sure they are eating well and exercising, and then, speak with a nutritionist or physician trained in nutrition to get advice on which supplements you may need. The best resources are physicians trained in nutrition and are board certified physician nutrition specialists (main.uab.edu/Sites/abpns/) and nutritionists with the credential certified nutrition specialist (CNS) as well as Registered Dietitian (RD).
Proteins are chains of amino acids. Nine of these proteinogenic amino acids are considered essential for humans because they cannot be produced from other compounds by the human body and so must be taken in as food. Recommended intakes, expressed as milligrams per kilogram of body weight per day, have been established. Other amino acids may be conditionally essential for certain ages or medical conditions. Amino acids, individually and in combinations, are sold as dietary supplements. The claim for supplementing with the branched chain amino acids leucine, valine and isoleucine is for stimulating muscle protein synthesis. A review of the literature concluded this claim was unwarranted. In elderly people, supplementation with just leucine resulted in a modest (0.99 kg) increase in lean body mass. The non-essential amino acid arginine, consumed in sufficient amounts, is thought to act as a donor for the synthesis of nitric oxide, a vasodilator. A review confirmed blood pressure lowering. Taurine, a popular dietary supplement ingredient with claims made for sports performance, is technically not an amino acid. It is synthesized in the body from the amino acid cysteine.
Calorie density. Junk foods are designed to convince your brain that it is getting nutrition, but to not fill you up. Receptors in your mouth and stomach tell your brain about the mixture of proteins, fats, and carbohydrates in a particular food, and how filling that food is for your body. Junk food provides just enough calories that your brain says, “Yes, this will give you some energy” but not so many calories that you think “That’s enough, I’m full.” The result is that you crave the food to begin with, but it takes quite some time to feel full from it.
Nutrition interventions that target mothers alone inadequately address women's needs across their lives: during adolescence, pre-conception, and in later years of life. They also fail to capture nulliparous women. The extent to which nutrition interventions effectively reach women throughout the life course is not well-documented. In this comprehensive narrative review, we summarized the impact and delivery platforms of nutrition-specific and nutrition-sensitive interventions targeting adolescent girls, women of reproductive age (non-pregnant, non-lactating), pregnant and lactating women, women with young children<5 years, and older women, with a focus on nutrition interventions delivered in low- and middle-income countries. We found that though there were many effective interventions that targeted women's nutrition, they largely targeted women who were pregnant and lactating or with young children. There were major gaps in the targeting of interventions to older women. For the delivery platforms, community-based settings, compared to facility-based settings, more equitably reached women across the life course, including adolescents, women of reproductive age, and older women. Nutrition-sensitive approaches were more often delivered in community-based settings, however, the evidence of their impact on women's nutritional outcomes was less clear. We also found major research and programming gaps targeting overweight, obesity, and non-communicable disease. We conclude that focused efforts on women during pregnancy and in the first couple of years postpartum fails to address the interrelation and compounding nature of nutritional disadvantages that are perpetuated across many women's lives. In order for policies and interventions to more effectively address inequities faced by women, and not only women as mothers, it is essential that they reflect how, when, and where to engage with women across the life course.
Folate or vitamin B9 (also known as folic acid when used in fortified foods or taken as a supplement) is another nutrient that many women don’t get enough of in their diets. Folate can greatly reduce the chance of neurological birth defects when taken before conception and during the first few weeks of pregnancy. Folate can also lower a woman’s risk for heart disease and certain types of cancer, so even if you’re not planning on getting pregnant (and many pregnancies are unplanned), it’s an essential nutrient for every woman of childbearing age. In later life, folate can help your body manufacture estrogen during menopause.
"These products provide a subtle, incremental effect. You can't use a sports supplement for a week and expect to gain pounds of muscle, but if used properly, research shows they can provide a slight, not overwhelming, edge," says Andrew Shoa, PhD, vice president for regulatory affairs for the Council for Responsible Nutrition, a trade association for the dietary supplement industry.
Carbohydrates should provide 45%–65% of your daily calories. Most of those calories should come from the complex carbohydrates in high-fiber and unrefined foods, such as bran cereal and other whole-grain products, brown rice, beans and other legumes, and many fruits and vegetables. These carbohydrates are digested and absorbed slowly, so they raise the blood sugar gradually and don't trigger a large release of insulin. People who eat lots of these foods have higher HDL ("good") cholesterol levels and a lower risk of obesity, diabetes, and heart disease. A good amount of soluble fiber in the diet lowers LDL ("bad") cholesterol, and high-fiber diets reduce the risk of intestinal disorders ranging from constipation and diverticulosis to hemorrhoids. Some studies have shown that fiber may help reduce the risk of colon cancer. Men need more fiber than women: 38 vs. 25 grams a day before the age of 50 and 30 vs. 21 grams a day thereafter.