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.
To assure supplements have sufficient quality, standardization, and safety for public consumption, research efforts have focused on development of reference materials for supplement manufacturing and monitoring. High-dose products have received research attention, especially for emergency situations such as vitamin A deficiency in malnutrition of children, and for women taking folate supplements to reduce the risk of breast cancer.
A well-known example is vitamin C, which can effectively fight viral infections, prevent or reverse disease caused by bacteria, and help the body detoxify organic and inorganic toxins.  Vitamin C also reduces the risk for cancer, strengthens connective tissues (collagen), and counteracts stress by increasing the adrenal´s production of cortisol. The dose required is set according to the body's need. Nobel Price Laureate Linus Pauling suggested that an optimal daily intake of vitamin C could vary from at least 250 mg up to 20 grams per day.  Because unabsorbed vitamin C attracts water into the gut, some people may experience loose stools, gas and/or diarrhea by ingesting only 1-2 grams at a time, while others with a higher level of stress may tolerate 5-6 grams or more. The dose that causes loose stools is called the "bowel tolerance" for vitamin C.  To avoid the laxative effect of high doses, it is best to take vitamin C throughout the day in smaller divided doses.
There’s a reason why many people eat as a way to cope with stress. Stress causes certain regions of the brain to release chemicals (specifically, opiates and neuropeptide Y). These chemicals can trigger mechanisms that are similar to the cravings you get from fat and sugar. In other words, when you get stressed, your brain feels the addictive call of fat and sugar and you’re pulled back to junk food.
Nutritionists are always saying to eat more vegetables, so cook them in a way that takes them from ho-hum to yum. "I even think that steamed veggies can be very boring!" says Ilyse Schapiro, a greater New York City-area registered dietitian. Always incorporate high-flavor add-ons to jazz up veggies, like sautéing with olive oil and garlic, or spraying them with olive oil before throwing them in an oven with salt, pepper, and garlic powder. That way, you don't equate "healthy" with "tasteless," a mindset that will knock you off the veggie bandwagon fast. Another tip: buy a spiralizer and make zucchini noodles. Topped off with a rich tomato sauce, you'll feel like you're eating pasta.
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."
Protein should provide about 15% of a healthy person's daily calories. As a rule of thumb, people of both sexes and any size will do fine with about 60 grams of protein a day. Athletes who have large muscles and work out hard may need 20% more. But even that's not very much; 8 ounces of chicken or 6 ounces of canned tuna, for example, will fit the bill.
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.
Now, the benefits of good nutrition are fairly obvious to most of us. You have more energy, your health improves, and your productivity blossoms. Healthy eating also plays a huge role in maintaining a healthy weight, which means a decreased risk of type 2 diabetes, certain cancers, heart problems, high blood pressure, and a host of other health ailments. (Genetics also plays a significant role. I'm not some crazy person who thinks genes don't matter.)
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.
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).
Sodium. Sodium is found in salt, but most of the sodium we eat does not come from salt that we add while cooking or at the table. Most of our sodium comes from breads and rolls, cold cuts, pizza, hot dogs, cheese, pasta dishes, and condiments (like ketchup and mustard). Limit your daily sodium to less than 2,300 milligrams (equal to a teaspoon), unless your doctor says something else. Check the Nutrition Facts label for sodium. Foods with 20% or more of the “Daily Value” of sodium are high in sodium.
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.
In general, healthy eating ingredients are found around the outer edges of most grocery stores, while the center aisles are filled with processed and packaged foods that aren’t good for you. Shop the perimeter of the store for most of your groceries (fresh fruits and vegetables, fish and poultry, whole grain breads and dairy products), add a few things from the freezer section (frozen fruits and vegetables), and visit the aisles for spices, oils, and whole grains (like rolled oats, brown rice, whole wheat pasta).
Nutrition is particularly important when you are pregnant. Weight gain during pregnancy is normal—and it's not just because of the growing fetus; your body is storing fat for lactation. The National Academy of Sciences/Institute of Medicine (NAS/IOM) has determined that a gain of 25 to 35 pounds is desirable. However, underweight women should gain about 28 to 40 pounds, and overweight women should gain at least 15 pounds. The IOM has not given a recommendation for an upper limit for obese women, but some experts cap it as low as 13 pounds. If you fit into this category, discuss how much weight you should gain with your health care professional. Remember that pregnancy isn't the time to diet. Caloric restriction during pregnancy has been associated with reduced birth weight, which can be dangerous to the baby.
Compared to pharmaceutical drugs, supplements of most essential nutrients are quite harmless. However, some supplements may have poor quality, or contain toxic metals such as lead or cadmium. Therefore, it is the duty of our authorities to ensure that potentially hazardous products or supplements of poor quality are not sold, and that consumers are offered fair prices in a free market. An example where the Norwegian authorities do not follow up such basic duties is that pharmacies demand more than 1,600 Norwegian Kroner (about $190) per kg of vitamin C in powder form, which would cost less than $20 with free competition and no restrictions in permitted doses or outlets.
Keep in mind that some ingredients found in dietary supplements are added to a growing number of foods, including breakfast cereals and beverages. As a result, you may be getting more of these ingredients than you think, and more might not be better. Taking more than you need is always more expensive and can also raise your risk of experiencing side effects. For example, getting too much vitamin A can cause headaches and liver damage, reduce bone strength, and cause birth defects. Excess iron causes nausea and vomiting and may damage the liver and other organs.
A 2013 study on herbal supplements found that many products were of low quality, one third did not contain the active ingredient(s) claimed, and one third contained unlisted substances. In a genetic analysis of herbal supplements, 78% of samples contained animal DNA that was not identified as an ingredient on the product labels. In some botanical products, undeclared ingredients were used to increase the bulk of the product and reduce its cost of manufacturing, while potentially violating certain religious and/or cultural limitations on consuming animal ingredients, such as cow, buffalo or deer. In 2015, the New York Attorney General identified four major retailers with dietary supplement products that contained fraudulent and potentially dangerous ingredients, requiring the companies to remove the products from retail stores.
Do you wonder if you need a dietary supplement? Maybe you do, but usually not. Ask yourself why you think you might want to take a dietary supplement. Are you concerned about getting enough nutrients? Is a friend, a neighbor, or someone on a commercial suggesting you take one? Some ads for dietary supplements in magazines, online, or on TV seem to promise that these supplements will make you feel better, keep you from getting sick, or even help you live longer. Often, there is little, if any, good scientific research supporting these claims. Supplements may cost a lot, could be harmful, or simply might not be helpful. Talk to your doctor or a registered dietitian for advice.
We've heard a lot of encouraging news about supplements. A series of studies hailed vitamin D as a possible defense against a long list of diseases, including cancer, diabetes, depression, and even the common cold. Omega-3 fatty acids have been touted for warding off strokes and other cardiovascular events. And antioxidants such as vitamins C and E and beta carotene were seen as promising silver bullets against heart disease, cancer, and even Alzheimer's disease.
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.