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What Your Doc Knows About Supplements…And You May Not

New guidance for doctors is out on vitamins and supplements. You might be surprised that a lot of the ones you might be taking are missing from the list.
What Your Doc Knows About Supplements...And You May Not
By Suzanne B. Robotti
Published: February 6, 2018
Last updated: February 8, 2018

Your physician may be the exception, but most medical schools barely teach their doctors-in-training about nutrition, much less vitamins and mineral supplements. Add to that the legitimate concerns that exist about the manufacturing quality of supplements and your doc might look like a deer in the headlights when you ask if Vitamin C can help fight your cold.

Doctors have been given new guidelines on vitamins and minerals and you should know what they are. Vitamin and Mineral Supplements: What Clinicians Need to Know was developed by 2 doctors — JoAnn E. Manson, MD, PhD, Division of Preventive Medicine, Brigham and Women’s Hospital, Harvard Medical School, and Shari Bassuk, SciD, Department of Epidemiology, Harvard T.H. Chan School of Public Health — and recently published in JAMA.

You know what vitamins are missing from the recommended list? Old standbys like Vitamin C, zinc and fish oil (Omega-3 fatty acids). Despite a lot of research, there’s no support for most vitamins and minerals. Instead, the list has a few very specific recommendations for people with particular conditions (like Crohn’s or age-related macular degeneration) or time of life (pregnancy, seniors) or to make up for what medicines take or block from you body (PPIs, metformin).

You know what else is missing? Any supplements for generally healthy people, including multivitamins. Where are we supposed to get our vitamins and minerals from? Eat complete (whole) foods in a varied diet.

I emailed Dr. Manson and she told me that for those who are generally healthy, routine supplementation is not necessary.

One last thought, if you are taking any supplements make sure that your doctor knows and that you choose a brand that is certified by independent testers like, US Pharmacopeia, NSF International, or UL who all test if supplements contain the labeled dose(s) of the active ingredient(s) and don’t contain microbes, heavy metals or other toxins.

Key Points on Vitamin and Mineral Supplements (source: JAMA)

General Guidance for Supplementation in a Healthy Population by Life Stage


  • Pregnancy: folic acid, prenatal vitamins

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  • Infants and children: for breastfed infants, vitamin D until weaning and iron from age 4-6 mo

  • Midlife and older adults: some may benefit from supplemental vitamin B12, vitamin D, and/or calcium

Guidance for Supplementation in High-Risk Subgroups


  • Medical conditions that interfere with nutrient absorption or metabolism:

    • Bariatric surgery: fat-soluble vitamins, B vitamins, iron, calcium, zinc, copper, multivitamins/multiminerals

    • Pernicious anemia: vitamin B12 (1-2 mg/d orally or 0.1-1 mg/mo intramuscularly)

    • Crohn disease, other inflammatory bowel disease, celiac disease: iron, B vitamins, vitamin D, zinc, magnesium

  • Osteoporosis or other bone health issues: vitamin D, calcium, magnesiuma

  • Age-related macular degeneration: specific formulation of antioxidant vitamins, zinc, copper

  • Medications (long-term use):

    • Proton pump inhibitorsa: vitamin B12, calcium, magnesium

    • Metformina: vitamin B12

  • Restricted or suboptimal eating patterns: multivitamins/multiminerals, vitamin B12, calcium, vitamin D, magnesium

a Inconsistent evidence.


The evidence is clear that women who may become pregnant or who are in the first trimester of pregnancy should be advised to consume adequate folic acid (0.4-0.8 mg/d) to prevent neural tube defects. Folic acid is one of the few micronutrients more bioavailable in synthetic form from supplements or fortified foods than in the naturally occurring dietary form (folate).2 Prenatal multivitamin/multimineral supplements will provide folic acid as well as vitamin D and many other essential micronutrients during pregnancy. Pregnant women should also be advised to eat an iron-rich diet. Although it may also be prudent to prescribe supplemental iron for pregnant women with low levels of hemoglobin or ferritin to prevent and treat iron-deficiency anemia, the benefit-risk balance of screening for anemia and routine iron supplementation during pregnancy is not well characterized.2

Supplemental calcium may reduce the risk of gestational hypertension and preeclampsia, but confirmatory large trials are needed.2 Use of high-dose vitamin D supplements during pregnancy also warrants further study.2 The American College of Obstetricians and Gynecologists has developed a useful patient handout on micronutrient nutrition during pregnancy.4

Infants and Children

The American Academy of Pediatrics recommends that exclusively or partially breastfed infants receive (1) supplemental vitamin D (400 IU/d) starting soon after birth and continuing until weaning to vitamin D–fortified whole milk (≥1 L/d) and (2) supplemental iron (1 mg/kg/d) from 4 months until the introduction of iron-containing foods, usually at 6 months.5 Infants who receive formula, which is fortified with vitamin D and (often) iron, do not typically require additional supplementation. All children should be screened at 1 year for iron deficiency and iron-deficiency anemia.

Healthy children consuming a well-balanced diet do not need multivitamin/multimineral supplements, and they should avoid those containing micronutrient doses that exceed the RDA. In recent years, ω-3 fatty acid supplementation has been viewed as a potential strategy for reducing the risk of autism spectrum disorder or attention-deficit/hyperactivity disorder in children, but evidence from large randomized trials is lacking.2

Midlife and Older Adults

With respect to vitamin B12, adults aged 50 years and older may not adequately absorb the naturally occurring, protein-bound form of this nutrient and thus should be advised to meet the RDA (2.4 μg/d) with synthetic B12 found in fortified foods or supplements.6 Patients with pernicious anemia will require higher doses (Box).

Regarding vitamin D, currently recommended intakes (from food or supplements) to maintain bone health are 600 IU/d for adults up to age 70 years and 800 IU/d for those aged older than 70 years.7 Some professional organizations recommend 1000 to 2000 IU/d, but it has been widely debated whether doses above the RDA offer additional benefits. Ongoing large-scale randomized trials (NCT01169259 and ACTRN12613000743763) should help to resolve continuing uncertainties soon.

With respect to calcium, current RDAs are 1000 mg/d for men aged 51 to 70 years and 1200 mg/d for women aged 51 to 70 years and for all adults aged older than 70 years.7 Given recent concerns that calcium supplements may increase the risk for kidney stones and possibly cardiovascular disease, patients should aim to meet this recommendation primarily by eating a calcium-rich diet and take calcium supplements only if needed to reach the RDA goal (often only about 500 mg/d in supplements is required).2 A recent meta-analysis suggested that supplementation with moderate-dose calcium (<1000 mg/d) plus vitamin D (≥800 IU/d) might reduce the risk of fractures and loss of bone mass density among postmenopausal women and men aged 65 years and older.2

Multivitamin/multimineral supplementation is not recommended for generally healthy adults.8 One large trial in US men found a modest lowering of cancer risk,9 but the results require replication in large trials that include women and allow for analysis by baseline nutrient status, a potentially important modifier of the treatment effect. An ongoing large-scale 4-year trial (NCT02422745) is expected to clarify the benefit-risk balance of multivitamin/multimineral supplements taken for primary prevention of cancer and cardiovascular disease.

Suzanne B. Robotti

Suzanne B. Robotti

Suzanne Robotti founded MedShadow Foundation in 2012. Learn more about Su and her mission.

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