Basic Nutrition - Dietary Supplements

A dietary supplement is a preparation—a pill, powder, or liquid—that contains nutrients or other substances and is consumed as part of one’s daily food intake to supply adequate or large dosages of a nutrient or compound.[1] Nutrients are components of food that provide energy, serve as building materials or regulate metabolic functions.  Dietary supplements are used to achieve one or more goals: optimize health (overall health and lack of disease), improve physical performance (muscular capacity or muscle size), or accomplish cosmetic goals (weight loss or bodybuilding).

Are dietary supplements beneficial?
Consider the following – 1) the typical American diet is high in fat and calories and limited in fruits, vegetables and whole grains; 2) current recommendations by the Department of Health and Human Services and the USDA are based on preventing deficiency disease rather than optimizing health and longevity and 3) it has been established that certain nutrients may prevent specific chronic diseases.[2] Unlike prescription drugs, there is minimal risk and little cost to ingesting certain nutrients above levels required to prevent deficiency and below levels that may result in adverse effects. Many well-known scientific and medical institutions including the American Medical Association and the Harvard School of Public Health recommend that everyone investigate the use of a multivitamin which provides insurance for a less than optimal diet.[3] Aside from a daily multivitamin there are other nutrients with sound, scientific evidence that warrant consideration.

Calcium and Vitamin D
Despite the importance of calcium and vitamin D in reducing the incidence of osteoporosis, intakes remain sub-optimal.[4,5] Populations at risk for inadequate intakes are adolescents, postmenopausal women and the elderly.[6,7,8] Sufficient amounts of calcium and vitamin D are required for bone health. Vitamin D is required for the absorption of calcium and increased levels of vitamin D have been shown to slow the rate of bone loss in the elderly.[9] It has been estimated that one billion individuals worldwide have inadequate vitamin D stores and deficiencies occur across all ages and ethnicities.[10] Furthermore, an association has been established between lower intakes of vitamin D and the risk of certain cancers (e.g., colorectal cancer).[11,12] Groups that are at especially at risk for low vitamin D status are the elderly and those who lack exposure to sunlight. However, even populations with sufficient sunlight exposure are at risk for vitamin D insufficiency, which underscores the importance of this fat-soluble vitamin.[13] Good sources of calcium and vitamin D are found in fortified dairy products, soybeans and sardines.

Fish Oils
Omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fatty fish and fish oil supplements have been shown to have cardioprotective effects[14], reduce triglyceride levels[15], reduce the progression of atherosclerosis,[14] possess anti-inflammatory properties[16] and support cognitive function.[17]  Major public health recommendations include consuming fatty fish such as herring, salmon and mackerel at least twice a week. However, those who do not eat fish should consider taking a daily omega-3 supplement of 500 to1000 milligrams with an EPA to DHA ratio of 1.75 to 1.[18,19,20]

Protein
People who engage in regular exercise or live an active lifestyle are likely to seek out the use of protein supplements to either enhance their training or health. Protein supplementation is appropriate for individuals with increased needs (e.g., athletes[21]) who do not get adequate protein through their diet or have a personal preference for additional protein barring certain health conditions. Table 5 contains protein guidelines for various exercisers. To date, research indicates there is no benefit to consuming protein in amounts greater than those listed below.[20] Doing so replaces foods that provide other essential nutrients.

Summary of Dietary Supplement Recommendations
A daily multivitamin is recommended for everyone to shore up various nutrients including the B vitamins, iron and vitamin C. For most people, obtaining the recommended daily intake of calcium and vitamin D is best achieved by taking a separate supplement since the levels in most multivitamins are inadequate. Therefore, if you do not consume at least three servings of dairy each day or you do not get daily sunlight exposure, taking a separate calcium and vitamin D may be beneficial. In adults, an additional 500 to 1000 milligrams of calcium per day will meet daily requirements and taking up to 2,000 IU of vitamin D is considered safe.[22] If you do not consume fatty fish twice a week, a fish oil supplement containing 500 to 1000 milligrams of EPA and DHA may be beneficial.



References

1  Spruce N, Titchenal A. An evaluation of popular fitness-enhancing supplements. USA:Evergreen Communications; 2001. 3p.
2  Krebs-Smith SM, Kris-Etherton P. How does MyPyramid compare to other population-based recommendations for controlling chronic disease? J Am Diet Assoc. 2007 May;107(5):830-7. Review.
3  Fairfield KM, Fletcher RH. Vitamins for chronic disease prevention in adults: scientific review. JAMA. 2002 Jun 19;287(23):3116-26. Review. Erratum in: JAMA 2002 Oct 9;288(14):1720.
4  Heaney RP. Low calcium intake among African Americans: effects on bones and body weight. J Nutr. 2006 Apr;136(4):1095-8. Review.
5  Hunt CD, Johnson LK. Calcium requirements: new estimations for men and women by cross-sectional statistical analyses of calcium balance data from metabolic studies. Am J Clin Nutr. 2007 Oct;86(4):1054-63.
6  Atkinson SA, McCabe GP, Weaver CM, Abrams SA, O'Brien KO. Are current calcium recommendations for adolescents higher than needed to achieve optimal peak bone mass? The controversy. J Nutr. 2008 Jun;138(6):1182-6.
7  Suzuki Y, Whiting SJ, Davison KS, Chilibeck PD. Total calcium intake is associated with cortical bone mineral density in a cohort of postmenopausal women not taking estrogen. J Nutr Health Aging. 2003;7(5):296-9.
8  Weatherall M. A meta-analysis of 25 hydroxyvitamin D in older people with a fracture of the proximal femur. N Z Med J 2000;1108:137– 40.
9  Prince RL, Austin N, Devine A, Dick IM, Bruce D, Zhu K. Effects of ergocalciferol added to calcium on the risk of falls in elderly high-risk women. Arch Intern Med. 2008 Jan 14;168(1):103-8.
10  Hanley DA, Davison KS. Vitamin D insufficiency in North America. J Nutr 2005;135:332–7.
11  Holick MF. Vitamin D and Sunlight: Strategies for Cancer Prevention and Other Health Benefits. Clin J Am Soc Nephrol. 2008 Jun 11. [Epub ahead of print]
12  Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008 Apr;87(4):1080S-6S. Review.
13  Jacobs ET, Alberts DS, Foote JA, Green SB, Hollis BW, Yu Z, Martínez ME. Vitamin D insufficiency in southern Arizona. Am J Clin Nutr. 2008 Mar;87(3):608-13.
14  Harper CR, Jacobson TA. Usefulness of omega-3 fatty acids and the prevention of coronary heart disease. Am J Cardiol. 2005 Dec 1;96(11):1521-9. Epub 2005 Oct 21.
15  Goldberg RB, Sabharwal AK. Fish oil in the treatment of dyslipidemia. Curr Opin Endocrinol Diabetes Obes. 2008 Apr;15(2):167-74. Review.
16  Luu NT, Madden J, Calder PC, Grimble RF, Shearman CP, Chan T, Dastur N, Howell WM, Rainger GE, Nash GB. Dietary supplementation with fish oil modifies the ability of human monocytes to induce an inflammatory response. J Nutr. 2007 Dec;137(12):2769-74.
17  Beydoun MA, Kaufman JS, Satia JA, Rosamond W, Folsom AR. Plasma n-3 fatty acids and the risk of cognitive decline in older adults: the Atherosclerosis Risk in Communities Study. Am J Clin Nutr. 2007 Apr;85(4):1103-11.
18  Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006 Oct 18;296(15):1885-99. Review. Erratum in: JAMA. 2007 Feb 14;297(6):590.
19  Harris WS, Pottala JV, Sands SA, Jones PG. Comparison of the effects of fish and fish-oil capsules on the n 3 fatty acid content of blood cells and plasma phospholipids. Am J Clin Nutr. 2007 Dec;86(6):1621-5.
20  Ruxton CH, Reed SC, Simpson MJ, Millington KJ. The health benefits of omega-3 polyunsaturated fatty acids: a review of the evidence. J Hum Nutr Diet. 2007 Jun;20(3):275-85.
21  Phillips SM. Dietary protein for athletes: from requirements to metabolic advantage. Appl Physiol Nutr Metab. 2006 Dec;31(6):647-54. Review.
22  Hollis BW.Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr. 2005 Feb;135(2):317-22. Review.



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