Generally, nutrients from food sources are more efficiently utilized by the body than isolated substances. For instance, fresh fruit and vegetable juice could be used to provide concentrated amounts of particular nutrients, such as vitamins A and C, to the diet. As another example, eating plenty of leafy green vegetables is a healthy option for those wishing to add calcium to the diet.
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.
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
The daily calcium recommendations are 1,000 milligrams a day for women under 50, and 1,500 milligrams a day for women 51 and older. Oddly enough, these are the same requirements for men, who are much less prone to osteoporosis than women. But the recommendation takes into account the fact that women are smaller than men. Thus the amount of daily calcium is greater for women on a proportional basis.
Trans fatty acids, also known as trans fats, are solid fats produced artificially by heating liquid vegetable oils in the presence of metal catalysts and hydrogen. They also pose a health risk, increasing LDL or "bad" cholesterol and increasing your risk of coronary heart disease. They are often found in cookies, crackers, icing and stick margarine, and in small amounts in meats and dairy products. Beginning in January 2006, all food manufacturers had to list the amount of trans fatty acids in foods, resulting in a significant reduction in the amount of these fats used in prepared foods. In its guidelines, the American Heart Association notes that trans fats increase risk of heart disease by raising "bad" LDL cholesterol and should be avoided as much as possible. In addition, research has shown that trans fats can also decrease "good" HDL cholesterol, increase inflammation, disrupt normal endothelial cell function and possibly interfere with the metabolism of other important fats—even more evidence that they are very bad for overall health.
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.