Themillion-dollar question of most patients revolve on what vitamins and supplements to take. Most physicians would have difficulty answering this even the most experienced ones. Anevaluation of the patient’s co-morbidities, current medicines, lifestyle, type of work, and reason for wanting to take supplements is required to respond to the question.Currently, vitamins and supplements have become very popular. A visit to the local pharmacy will reveal various combinations of vitamins and mineral supplements that are packaged with very attractive health claims from manufacturers.
Despite the popularity of most vitamins and supplements, randomized controlledtrials (RCT) have not demonstrated clear benefits of vitamins for diseases other than micronutrient deficiency. In fact, there are numerous RCTs which suggest that micronutrient supplementation exceeding the recommended dietary allowance (RDA) may have harmful effects. These include increased mortality, cancer, and hemorrhagic stroke.Therefore, the physician has to promote appropriate use of such vitamins and supplements.
It is the physician’s task to counsel patients that a healthy and balanced diet cannot be substituted with supplements. Micronutrients in food are better absorbed by the body and are associated with fewer potential adverse effects. Various researches have shown a strong relation between dietary patterns and specific food types than to individual micronutrient or supplement intake.
General Guidance for Supplementation in a Healthy Population by Life Stage
Strong evidence has been found to advice the pregnant especially those in their first trimester of pregnancy to take supplementary folic acid (0.4-0.8 milligrams per day or mg/d) to prevent neural tube defects. Supplementary folic acid is needed because it is one of the few micronutrients that is more bioavailable in its synthetic form which could be obtained from supplements than in naturally occurring dietary form.
Pregnant women should be advised to have an iron-rich diet. It may seem practical to give iron supplements for the treatment of iron-deficiency anemia and for pregnant women especially those with low levels of hemoglobin or ferritin. However, risk factors for anemia and the screening of anemia and supplementation of iron to pregnant women are not well categorized.
Risks for gestational hypertension and preeclampsia may be reducedby supplemental calcium but confirmatory large trials are needed to establish its strong relation.
Infants and Children
A recommendation by the American Academy of Pediatrics states that exclusively or partially breastfed infants should receive:
- supplemental vitamin D (400 International Units per day or IU/d) after birth and continue until weaning to vitamin D-fortified whole milk (> 1Liter/day or 1L/d) and
- supplemental iron (1 mg/kg/d) from 4 months until the introduction of iron-containing diet whichis usually started at 6 months.
Infants who receive formula milk that is fortified with vitamin D and iron need not be given any iron supplementation. Screening for iron deficiency and iron deficiency anemia should be done to all children at 1 year old.
Children that are classified as healthy and eat a balanced diet do not need to take supplements, instead they are advised to avoid multivitamins that contain micronutrients that exceed the RDA. Though large randomized trials are still lacking, some studies in the recent years have showed thatomega-3 (ω-ɜ) fatty acid supplementation has been considered a probable strategy to reduce the risk of developing autism spectrum disorder or attention deficit/hyperactivity disorder (ADHD) in children.
Midlife and Older Adults
Adults aged 50 years and above could not adequately absorb the naturally occurring vitamin B12, hence they are advised to take synthetic B12 found in supplements so as to meet the RDA of 2.4 ug/d. To maintain bone health, the recent RDA for adults up to 70 years old is 600 IU/d while it is 800 IU/d for ages 70 years old and above. Though some professional organizations are still recommending 1000-2000 IU/d, it is still being debated if there would be additional benefits or harm if doses above RDA are given. Fortunately,a large RCT is ongoing that could resolve this ambiguity.
The current RDA for calcium is 1000mg/d for men aged 51-70 years old and 1200 mg/d for women aged 51-70 years old and for all adults above 70 years old. Calcium supplements have been found to increase the risk of kidney stones, hence patients are advised to eat calcium-rich diet to reach the RDA. If the RDA has not been met, calcium supplements could be taken but a 500mg/d calcium supplement should be enough. Intake of moderate-dose calcium (<100 mg/d) plus vitamin D (>800 IU/d) could reduce the risk of fractures and loss of bone mass density among postmenopausal women and men aged 65 and above.
Healthy adults are not advised to take multivitamins or mineral supplementation. However, one large study on men showed that cancer risk is lowered in patients who are taking supplements. The study is currently being replicated in a large-scale 4-year trial to clarify the benefit-risk balance of intake of multivitamin supplements as primary prevention for cancer and cardiovascular diseases.
Guidance for Supplementation in High-Risk Subgroups
When recommending a multivitamin or a micronutrient supplement, clinicians should consider the patient’s health status in order to be able to counsel them on the potential interactions. There are some medical conditions that could affect nutrient absorption or metabolism. Patients who have undergone bariatric surgery are recommended to have supplements such as fat-soluble vitamins, B vitamins, iron, calcium, zinc, copper and multivitamins or multiminerals. Those who have pernicious anemia are advised to have 1-2mg/d oral or 0.1-1mg/month IM of vitamin B12. Patients who have Crohn disease, inflammatory bowel disease, and celiac disease should be supplemented with iron, B vitamins, vitamin D, zinc, and magnesium. Vitamin D, calcium, and magnesium supplements should be given to patients with osteoporosis.
Although there is inconsistent evidence, patients that are taking long term medications such as proton pump inhibitors are advised to take in vitamin B12, calcium, and magnesium supplements. Long term use of metformin has also been noted to cause deficiency of vitamin B12, hence supplements are advised. Individuals with restricted or suboptimal eating patterns should takesupplements, particularly vitamin B12, vitamin D, calcium, and magnesium.
Other Key Points
TheFood and Drug Administration (FDA) regulates vitamin products, however they are not authorized to review the dietary supplements for safety and efficacy before these are released into the market. The FDA makes sure that the manufacturers adhere to the agency’s Good Manufacturing Practice regulations requiring the manufacturers to evaluate their products through testing identity, purity, strength, and composition. Some physicians prefer specific brands or advice their patients to select a supplement that have been certified by independent testers to contain the exact labeled dose of the active ingredients and to be free from microbes, heavy metals, or other toxins.
Physicians and patients are obliged to report suspected supplement-related adverse effects to the FDA. Physicians could greatly improve public health by promoting appropriate use and stopping inappropriate use of micronutrient supplements.
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Rautiainen S, Manson JE, Lichtenstein AH, Sesso HD. Dietary supplements and disease prevention: a global overview. Nat Rev Endocrinol. 2016; 12(7):407-420.
Marra MV, Boyar AP. Position of the American dietetic Association: Nutrient Supplementation. J Am Diet Assoc. 2009;109(12):2073-2085
American Academy of Pediatrics. Vitamin D and Iron supplements for babies AAP recommendations. HealthyChildren.org
Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academies Press; 2011.