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More than 50 percent of Americans take some type of supplement, according to a 2009 article published in "U.S. News and World Report." However, some of these individuals exceed the upper limit for one or more nutrients. This can cause problems because some vitamins and minerals compete for absorption or inhibit the absorption of others.
Vitamin and mineral supplements come in two main varieties: multivitamin and mineral supplements that contain most or all of the necessary vitamins and minerals people need to stay healthy, and single vitamin or mineral supplements that provide large amounts of just one nutrient.
Why Food Is Better Than Supplements
Many people take a multivitamin as a "safety net" in case they do not get enough of some vitamins through their daily diet. Others take specific vitamins, either as recommended by a doctor, as in the case of iron for those who are anemic, or through self-medicating in the hopes of lessening their chances of getting ill after hearing about the benefits of a particular vitamin or mineral. One example is calcium and vitamin D supplements for those wanting to prevent osteoporosis. However, mega-doses of specific vitamins and minerals can be toxic or interfere with the absorption of others, so you should discuss your supplement use with your doctor.
- Many people take a multivitamin as a "safety net" in case they do not get enough of some vitamins through their daily diet.
- Others take specific vitamins, either as recommended by a doctor, as in the case of iron for those who are anemic, or through self-medicating in the hopes of lessening their chances of getting ill after hearing about the benefits of a particular vitamin or mineral.
Competing for Absorption
There are a number of vitamin-mineral and mineral-mineral interactions that can cause problems for those who take high-dose supplements. Vitamin C can inhibit copper absorption, and too much copper can lead to vitamin C deficiency. Zinc inhibits both copper and iron; magnesium, copper, iron and calcium all compete for absorption, so too much of one can lead to low blood levels of the others.
Zinc & Cold Sores
Multivitamins and mineral supplements are a good way to get balanced amounts of vitamins and minerals because most supplements are formulated to take interactions into account. "Perspectives in Nutrition" recommends taking a supplement that doesn't provide more than 100 percent of the Daily Value, or DV, for any nutrient 1.
When taking supplements of individual vitamins and minerals, such as zinc, Dr. Jeremy Kaslow of DrKaslow.com recommends also taking supplements of complementary vitamins and minerals so the levels of each are kept in the right proportions 4. A doctor or registered dietitian can help you figure out the right amounts, as well as whether you need the supplement in the first place.
Why Food Is Better Than Supplements
Zinc & Cold Sores
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Iron Supplements & Orange Juice
What Is IU on Vitamins?
- "Perspectives in Nutrition"; Gordon Wardlaw; 1999
- Office of Dietary Supplements: Dietary Supplement Fact Sheet--Iron
- DrWilson.com: Copper Toxicity Syndrome
- DrKaslow.com: Zinc Deficiency and Metabolism
- Albahrani AA, Greaves RF. Fat-Soluble Vitamins: Clinical Indications and Current Challenges for Chromatographic Measurement. Clin Biochem Rev. 2016;37(1):27–47.
- Selhub J, Paul L. Folic acid fortification: why not vitamin B12 also? Biofactors. 2011;37(4):269-71. doi:10.1002/biof.173
- Ebben M, Lequerica A, Spielman A. Effects of pyridoxine on dreaming: a preliminary study. Percept Mot Skills. 2002;94(1):135-40. doi:10.2466/pms.2002.94.1.135
- U.S. National Library of Medicine. ToxNet: Nicotinic acid. Updated November 28, 2018.
- Chambial S, Dwivedi S, Shukla KK, John PJ, Sharma P. Vitamin C in disease prevention and cure: an overview. Indian J Clin Biochem. 2013;28(4):314–328. doi:10.1007/s12291-013-0375-3
- Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington (DC): National Academies Press; 2000.
- Golan D, Staun-ram E, Glass-marmor L, et al. The influence of vitamin D supplementation on melatonin status in patients with multiple sclerosis. Brain Behav Immun. 2013;32:180-5. doi:10.1016/j.bbi.2013.04.010
- Mason C, de Dieu Tapsoba J, Duggan C, Wang CY, Korde L, McTiernan A. Repletion of vitamin D associated with deterioration of sleep quality among postmenopausal women. Prev Med. 2016;93:166–170. doi:10.1016/j.ypmed.2016.09.035
- Rizvi S, Raza ST, Ahmed F, Ahmad A, Abbas S, Mahdi F. The role of vitamin E in human health and some diseases. Sultan Qaboos Univ Med J. 2014;14(2):e157–e165.
- DiNicolantonio JJ, Bhutani J, O'Keefe JH. The health benefits of vitamin K. Open Heart. 2015;2(1):e000300. doi:10.1136/openhrt-2015-000300
- NIH Osteoporosis and Related Bone Diseases National Resource Center. Calcium and Vitamin D: Important at Every Age. Updated October 2018.
- Ross AC. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academies Press; 2011.
- Straub DA. Calcium supplementation in clinical practice: a review of forms, doses, and indications. Nutr Clin Pract. 2007;22(3):286-96. doi:10.1177/0115426507022003286
- U.S. National Library of Medicine. ToxNet: Calcium Compounds. Updated January 29, 2000.
- Gröber U, Schmidt J, Kisters K. Magnesium in Prevention and Therapy. Nutrients. 2015;7(9):8199–8226. doi:10.3390/nu7095388
- U.S. National Library of Medicine. DailyMed: Milk of Magnesia. Updated October 19, 2018.
- Kantor ED, Rehm CD, Du M, White E, Giovannucci EL. Trends in Dietary Supplement Use Among US Adults From 1999-2012. JAMA. 2016;316(14):1464–1474. doi:10.1001/jama.2016.14403
Based in Massachusetts, Jessica Bruso has been writing since 2008. She holds a master of science degree in food policy and applied nutrition and a bachelor of arts degree in international relations, both from Tufts University.