There are two main ways to use vitamins and mineral supplements: "megadose" and nutritional therapy.
The megadose approach involves taking supplements at doses far above nutritional needs in hopes of producing a specific medical benefit. This technique essentially uses nutrients as natural drugs. The individual supplement articles in this encyclopedia explain what is known about the potential risks and benefits of megadose therapy.
This article addresses the second approach: taking nutrients at the level of nutritional needs. We discuss general issues regarding such "nutritional insurance" and indicate which nutrients you should consider taking on a daily basis.
There is no doubt that it's important to get enough of all necessary nutrients. However, the process of determining proper daily intake levels for vitamins and minerals is far from an exact science and the recommendations issued by experts in various countries often disagree to a certain extent.
In general, while it is fairly easy to determine the minimum nutrient intakes that are necessary to avoid frank malnutrition, there's no straightforward way to determine optimum intake levels. Furthermore, individual needs undoubtedly vary based on numerous factors, including age, genetics, lifestyle, other foods in the diet, and many additional environmental influences; no schedule of official recommendations could possibly take all these factors into account, even if all the necessary data existed (which it doesn't).
Thus, all recommendations for daily nutrient intake must be regarded as approximate. The individual supplement articles in this encyclopedia summarize the current US recommendations.
Common Nutritional Deficiencies
Severe deficiencies of vitamins or minerals are rare in the developed world. However, evidence suggests that slight deficiencies in certain nutrients may be relatively common. These include calcium , 15,16chromium , 14folate , 13magnesium , 17 vitamin B 6 , 18-20vitamin C , 21-24 vitamin B 12 (primarily in the elderly), 25-28vitamin D , 33vitamin E , 40-42 and zinc . 16,34-37
While few people are so deficient in these nutrients to show symptoms of outright malnutrition, subtle deficiencies may increase the risk of a number of diseases. For example, insufficient intake of calcium and vitamin D may increase your chances of developing osteoporosis, and inadequate folate and vitamin B 6 may speed the development of heart disease.
Thus, taking supplements to supply these important vitamins and minerals as a form of insurance may be a good idea. For standard dosage recommendations as well as safety issues, follow the links above to the full articles.
Women may develop iron deficiency, but men hardly ever do. Even in women, iron supplements are not beneficial in the absence of true deficiency. We recommend avoiding iron supplements unless tests show that you really need them.
The simplest way to support your nutrition is to take a general multivitamin and mineral supplement providing a broad range of nutrients at standard nutritional levels. However, there are a few caveats to keep in mind.
Taking Individual Supplements
One problem with multivitamin/mineral supplements is that some nutrients may interfere with the absorption of others. For this reason, there may be advantages to taking supplements separately. (The hassle factor is a strong disadvantage!) In addition, this method allows one to avoid taking vitamins and minerals one doesn't need.
If you do use this approach, keep in mind the following:
Natural vs. Synthetic Vitamins
Many people wonder whether "natural" vitamins are better than "synthetic" ones. This question, however, is a bit of a red herring. Ultimately, no vitamin or mineral supplement is "natural." Purified vitamins and minerals are refined, processed products analogous to white sugar or artificial fertilizer. It doesn't much matter whether they are extracted from foods or manufactured in a laboratory: the result is the same. For example, vitamin C made from rose hips is chemically identical to vitamin C synthesized from scratch. Both are ascorbic acid.
Rose hips themselves, however, supply many nutrients along with vitamin C. If you truly wish to get your vitamins naturally, you might consider taking them as freeze-dried or condensed whole food supplements rather than as purified vitamins. This might offer a specific advantage over purified vitamins: as we noted above, fruits and vegetables may provide substances that are not actually essential but that promote better health.
Under certain conditions, the need for many nutrients may increase. These include illnesses such as diabetes , Crohn's disease , HIV , and ulcerative colitis . Furthermore, individuals who smoke cigarettes or overuse alcohol may need additional nutrients. Follow the links to the individual articles for more information.
Medications may increase the need for certain nutrients; if you look up your own medications in the Drug Interaction section of this encyclopedia, you will find what is known about these so-called nutrient depletions.
Other potential uses of multivitamins generally lack strong support.
Some but not all evidence hints that multivitamin/multimineral supplements may help prevent infections in seniors or otherwise enhance immunity. 7, 8, 9, 32,38,39,43,57,63-64 However, there are strong suspicions that scientific fraud may have tainted this research, and when the potentially fraudulent studies are disregarded the evidence looks more negative than positive. 70
Similarly, some but not all studies suggest that multivitamin/multimineral supplements can enhance mental function , and here, too, there are concerns about potential fraud. 11,12,48-51,58,59, 62,71,74 In general, the best designed studies have failed to find benefit. However, it is quite possible that multivitamin/multimineral supplements are helpful for people with marked vitamin or mineral malnutrition. 71
One study found that use of a multivitamin tablet improved mood, but not cognitive function, in hospitalized acutely ill seniors. 72 Another study failed to find that a mix of multivitamin (either general, or consisting of B-complex vitamins) were more effective than placebo for treating depression in healthy young adults. 75
Incomplete, and in some cases contradictory, evidence suggests that use of multivitamin and/or multimineral supplements might reduce antisocial behavior in children and young adults (especially those who are malnourished), 40,47,52 prevent pressure ulcers (bed sores), 54 lower blood pressure , 53 improve fertility in women , 10 improve general well-being , 47,51, 65enhance sports performance , 67 enhance growth in children, 56 speed healing of minor wounds,55 reduce the pain of osteoarthritis , 46 reduce pregnancy-related nausea (“morning sickness”), 47decrease risk of numerous birth defects , 68 help control menopausal hot flashes , 69 decrease symptoms of premenstrual stress syndrome (PMS)1-4 and ordinary stress , 5,6reduce risk of prostate cancer , 66 and help prevent cataracts . 76
In a double-blind study of 40 people undergoing radiation therapy for breast cancer, use of a standard multivitamin preparation failed to reduce fatigue as compared to placebo. 73 (In fact, people in the placebo group may have done somewhat better than those given the vitamin.)
Standard multivitamin/multimineral tablets contain nutrients at levels believed to be safe for the majority of healthy people, as indicated by amounts at or below the recommended daily allowance. However, even these supplements could be harmful for people with certain diseases, such as kidney or liver disease, or for people taking certain medications, such as warfarin .
There are other multivitamin/multimineral tablets that contain high levels of certain nutrients far above nutritional needs. These could conceivably present risks for healthy people, particularly if they are taken in combination with additional specific supplements. Almost any mineral can be toxic if taken to excess, and there are also risks with excessive intake of vitamins A, B 6 , and D.
One study found that use of multivitamin/mineral supplements may actually increase the infectivity of women with HIV. 61 The reasons for this are unclear.
1. London RS, Bradley L, Chiamori NY. Effect of a nutritional supplement on premenstrual symptomatology in women with premenstrual syndrome: a double-blind longitudinal study. J Am Coll Nutr. 1991;10:494-499.
4. Chakmakjian ZH, Higgins CE, Abraham GE. The effect of a nutritional supplement, OptiviteŴ for women, on premenstrual tension syndromes: II. Effect on symptomatology, using a double-blind, cross-over design. J Appl Nutr. 1985;37:12-17.
5. Schlebusch L, Bosch BA, Polglase G, et al. A double-blind, placebo-controlled, double-centre study of the effects of an oral multivitamin-mineral combination on stress. S Afr Med J. 2000;90:1216-1223.
6. Carroll D, Ring C, Suter M, et al. The effects of an oral multivitamin combination with calcium, magnesium, and zinc on psychological well-being in healthy young male volunteers: a double-blind placebo-controlled trial. Psychopharmacology (Berl). 2000;150:220-225.
7. Girodon F, Galan P, Monget AL, et al. Impact of trace elements and vitamin supplementation on immunity and infections in institutionalized elderly patients: a randomized controlled trial. MIN. VIT. AOX. geriatric network. Arch Intern Med. 1999;159:748-754.
17. Alaimo K, McDowell MA, Briefel RR, et al. Dietary intake of vitamins, minerals and fiber of persons age 2 months and over in the United States: Third National Health and Nutrition Examination Survey, phase 1, 1988-91. Advance Data from Vital and Health Statistics. 1994;258:1-26.
29. Barringer TA, Kirk JK, Santaniello AC, et al. Effect of a multivitamin and mineral supplement on infection and quality of life. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2003;138:365-371.
31. Berger MM, Spertini F, Shenkin A, et al. Trace element supplementation modulates pulmonary infection rates after major burns: a double-blind, placebo-controlled trial. Am J Clin Nutr. 1998;68:365-371.
32. Graat JM, Schouten EG, Kok FJ. Effect of daily vitamin E and multivitamin-mineral supplementation on acute respiratory tract infections in elderly persons: a randomized controlled trial. JAMA. 2002;288:715-721.
40. Schoenthaler SJ, Amos S, Doraz W, et al. The effect of randomized vitamin-mineral supplementation on violent and non-violent antisocial behavior among incarcerated juveniles. J Nutr Environ Med. 1977;7:343-352.
44. Czeizel AE, Dudas I, Fritz G, et al. The effect of periconceptional multivitamin-mineral supplementation on vertigo, nausea and vomiting in the first trimester of pregnancy. Arch Gynecol Obstet. 1992;251:181-185
45. Ussher JM, Dewberry C, Malson H, et al. The relationship between health related quality of life and dietary supplementation in British middle managers: a double blind placebo controlled study. Psychol Health. 1995;10:97-111.
46. Colker CM, Swain M, Lynch L, et al. Effects of a milk-based bioactive micronutrient beverage on pain symptoms and activity of adults with osteoarthritis: a double-blind, placebo-controlled clinical evaluation. Nutrition. 2002;18:388-392.
47. Schoenthaler SJ, Bier ID. The effect of vitamin-mineral supplementation on juvenile delinquency among American schoolchildren: a randomized, double-blind placebo-controlled trial. J Altern Complement Med. 2000;6:7-17.
52. Gesch CB, Hammond SM, Hampson SE, et al. Influence of supplementary vitamins, minerals and essential fatty acids on the antisocial behaviour of young adult prisoners. Randomised, placebo-controlled trial. Br J Psychiatry. 2002;181:22-28.
54. Houwing RH, Rozendaal M, Wouters-Wesseling W, et al. A randomised, double-blind assessment of the effect of nutritional supplementation on the prevention of pressure ulcers in hip-fracture patients. Clin Nutr. 2003;22:401-405.
55. Brown SA, Coimbra M, Coberly DM, et al. Oral nutritional supplementation accelerates skin wound healing: a randomized, placebo-controlled, double-arm, crossover study. Plast Reconstr Surg. 2004;114:237-244.
56. Ramakrishnan U, Aburto N, McCabe G, et al. Multimicronutrient interventions but not vitamin a or iron interventions alone improve child growth: results of 3 meta-analyses. J Nutr. 2004;134:2592-602.
57. Langkamp-Henken B, Bender BS, Gardner EM, et al. Nutritional formula enhanced immune function and reduced days of symptoms of upper respiratory tract infection in seniors. J Am Geriatr Soc. 2004;52:3-12.
58. Meguid MM, Shenkin A. Introduction: nutritional supplements and the quest to improve human performance—the need for the strictest standards and rigor when reporting clinical trials. Nutrition. 2003;19:955-956.
60. Allsup SJ, Shenkin A, Gosney MA, et al. Can a short period of micronutrient supplementation in older institutionalized people improve response to influenza vaccine? A randomized, controlled trial. J Am Geriatr Soc. 2004;52:20-24.
61. McClelland RS, Baeten JM, Overbaugh J, et al. Micronutrient supplementation increases genital tract shedding of HIV-1 in women: results of a randomized trial. J Acquir Immune Defic Syndr. 2004;37:1657-1663.
62. Wolters M, Hickstein M, Flintermann A, et al. Cognitive performance in relation to vitamin status in healthy elderly German women-the effect of 6-month multivitamin supplementation. Prev Med. 2005;41:253-259.
63. Avenell A, Campbell MK, Cook JA, et al. Effect of multivitamin and multimineral supplements on morbidity from infections in older people (MAVIS trial): pragmatic, randomised, double blind, placebo controlled trial. BMJ. 2005;331:324-329.
64. El-Kadiki A, Sutton AJ. Role of multivitamins and mineral supplements in preventing infections in elderly people: systematic review and meta-analysis of randomised controlled trials. BMJ. 2005 Mar 31. [Epub ahead of print]
71. McNeill G, Avenell A, Campbell MK, et al. Effect of multivitamin and multimineral supplementation on cognitive function in men and women aged 65 years and over: a randomised controlled trial. Nutr J. 2007 May 2. [Epub ahead of print]
73. de Souza Fede AB, Bensi CG, Trufelli DC, et al. Multivitamins do not improve radiation therapy-related fatigue: results of a double-blind randomized crossover trial. Am J Clin Oncol. 2007;30:432-436.
74. The NEMO Study Group. Effect of a 12-mo micronutrient intervention on learning and memory in well-nourished and marginally nourished school-aged children: 2 parallel, randomized, placebo-controlled studies in Australia and Indonesia. Am J Clin Nutr. 2007;86:1082-1093.
76. A randomized, double-masked, placebo-controlled clinical trial of multivitamin supplementation for age-related lens opacities clinical trial of nutritional supplements and age-related cataract report no. 3. Ophthalmology. 2008;115:599-607.e1.
Last reviewed December 2015 by EBSCO CAM Review Board
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