Healthy Eating

Most micronutrient needs can be met by following a healthy eating pattern that emphasizes consumption of nutrient-dense food and beverages, including a variety of vegetables, whole fruit and 100% fruit juice, legumes, whole grains, dairy, nuts, seeds, oils, as well as lean meat, poultry, and/or seafood (1). The 2015-2020 Dietary Guidelines for Americans — issued jointly by the US Department of Health and Human Services and US Department of Agriculture — discuss various healthy eating patterns: the "Healthy US-style Eating Pattern," the "Healthy Mediterranean-style Eating Pattern," and the "Healthy Vegetarian Eating Pattern" (see Chapter 1 of the US Dietary Guidelines) (1). Moreover, the Dietary Approaches to Stop Hypertension (DASH) eating pattern is a similar eating pattern that would ensure most micronutrient needs are met — randomized controlled trials have found that adherence to the DASH eating pattern reduces risk factors of cardiovascular disease, including blood pressure (see the article on Sodium).

Specific recommendations of the Dietary Guidelines are to eat a variety of vegetables, including dark-green (e.g., broccoli, lettuce, spinach, kale), red and orange (e.g., tomatoes, carrots, peppers, pumpkin), starchy (e.g., potatoes, corn, green peas), and other (e.g., eggplant, cucumbers, beets, avocados) vegetables, as well as legumes (beans, lentils, peanuts, and peas). For more examples, see Table 2.1 in the Dietary Guidelines. Recommendations also emphasize the consumption of whole fruit (fresh, frozen, canned, or dried); a limited amount of 100% fruit juice without added sugars can also contribute to fruit intake (1). Those who consume fruit juice have higher intakes of vitamin A, folate, vitamin C, potassium, magnesium, and phosphorus compared to nonconsumers (reviewed in 2). However, fruit juice is much lower in dietary fiber than whole fruit, and the Dietary Guidelines recommend that at least half of fruit intake be whole fruit (1). The American Academy of Pediatrics recommends that no fruit juice be given to infants and that the amount of 100% fruit juice be limited to 4-8 ounces in young children, depending on age (see the American Academy of Pediatrics website). The recommended amounts of fruit and vegetables are based on estimated energy needs that vary with age, gender, and level of physical activity. Recommended daily intakes of fruit and vegetables at all calorie requirement levels can be found in the "2015-2020 Dietary Guidelines for Americans" report (see Appendices 3-5) (3). Table 1 provides the amounts of fruit and vegetables (expressed in cup-equivalents) that are recommended at the 2,000-calorie per day level. For detailed information on the health benefits of fruit and vegetables, see the article on Fruit and Vegetables.

Table 1. 2015-2020 US Dietary Guideline Recommendations for Fruit and Vegetable Intakes*
Food Healthy Eating Patterns
US-style Mediterranean-style Vegetarian
Vegetables (c-eq/day)
 Dark-green vegetables (c-eq/week)  1½  1½
 Red and orange vegetables (c-eq/week)  5½
 Legumes (c-eq/week)  1½  1½  1½
 Starchy vegetables (c-eq/week)  5 5  5
 Other vegetables (c-eq/week)  4 4  4
Fruit (c-eq/day)  2  2½  2

*Recommendations for fruit and vegetable intakes at the 2,000-calorie per day level. Estimates of daily calorie needs according to age, gender, and physical activity can be found in the Appendix 2 of the ‘2015-2020 Dietary Guidelines for Americans’ report (1).
c-eq, cup-equivalents

The Dietary Guidelines for Americans also emphasize eating whole grains; at least half of all grains consumed daily should be whole grains (i.e., at least three servings [~90 g] of whole-grain products). Refined grains are subject to a milling process that removes the outer bran and inner germ layers from grains, leaving only the middle endosperm layer — this results in the loss of several micronutrients, phytochemicals, and dietary fiber. Enrichment returns some (thiamin, riboflavin, niacin, folic acid, and iron), but not all, micronutrients lost during milling (see the graphs on the Whole Grain Council website). The Dietary Guidelines recommend that people who consume refined grains choose these "enriched grains" and that those who eat only whole grains also include some grains that are fortified with folic acid (1). While whole grains are a source of numerous biologically active components (see Table 2), consumption of both whole grains and enriched grains together may help close nutrient gaps (4, 5). A micronutrient gap exists if one does not meet the dietary requirement (i.e., EAR) for that nutrient. Such nutrient gaps are common in the US population because many micronutrients are underconsumed. Underconsumed nutrients are often labeled as 'nutrients of concern’ or ‘shortfall nutrients' (see the article, Micronutrient Inadequacies in the US Population: An Overview) (1).

It is important to note that diets rich in whole grains have been associated with lower risks of type 2 diabetes mellitus and cardiovascular disease compared to diets rich in refined grains (see the article on Whole Grains).

Table 2. Some Potentially Beneficial Compounds in Whole Grains
Macronutrients Vitamins Minerals Phytochemicals
 Unsaturated Fats Folate Magnesium Fiber
  Vitamin E Potassium Flavonoids
    Selenium Lignans
      Phytosterols

Dairy is a source of several micronutrients, including vitamins A, B12, and D; riboflavin; choline; and the minerals, calcium, magnesium, and zinc. The Dietary Guidelines recommend consuming low-fat dairy (2 to 3 cup-equivalents/day) as part of a healthy eating pattern, stating that dairy includes milk, cheese, yogurt, and fortified soy beverages (1). However, other plant-based beverages, such as almond, cashew, or coconut "milk," which are not dairy products, may be fortified with calcium, vitamin A, and vitamin D and thus provide similar micronutrients as cow’s milk. Modeling studies have found that increasing dairy intake to near recommendations would result in significant reductions in the number of Americans with inadequacies in calcium, magnesium, vitamin A, and vitamin D (6, 7) — all of these nutrients are underconsumed in the US population.

As mentioned above, adherence to a healthy eating pattern includes various protein foods, including lean meat, poultry and/or seafood, as well as nuts, seeds, and legumes. For examples of foods rich in certain micronutrients, see the Linus Pauling Institute’s "Micronutrients for Health" handout and the "Sources" section in articles on specific vitamins or minerals. Additionally, some food sources of potassium, calcium, and vitamin D are listed in the Dietary Guidelines Appendixes, and comprehensive lists of food sources can be downloaded for most nutrients from the USDA food composition database. Even when following a healthy eating pattern, it is very difficult to meet the dietary recommendation (i.e., the RDA) for vitamin D (3), which is found only in a few foods, making fortified food and supplements important sources. Conversely, sodium is a mineral that is overconsumed by the US population: 90% of US adults surveyed in NHANES 2011-2012 had daily sodium intakes in excess of the tolerable upper intake level (UL) (8). Sodium in the diet comes mainly from salt in processed food (9). For information on adverse effects of consuming too much sodium, including high blood pressure, see the Safety section in the article on sodium.

Fortified Food

Fortification refers to the addition of nutrients to food to prevent or correct a nutritional deficiency, to balance the total nutrient profile of food, or to restore nutrients lost in processing (called 'enrichment'). Food fortification is often used to combat specific micronutrient deficiencies within a population but may also address micronutrient inadequacies (underconsumed or 'shortfall' nutrients) in well-nourished nations (10). There is concern, however, that fortification may result in excessive intakes of some micronutrients, i.e., nutrient intakes above the UL, especially in children (11). Fortification can be voluntarily done by food manufacturers or mandated by the government of a nation. In the US, the FDA regulates the addition of nutrients to food under the Federal Food, Drug, and Cosmetic Act; manufacturers must list the nutrients added to food on the "Nutrition Facts" label (12) and state the minimum amount of nutrient per serving accounting for shelf life (13).

Fortification of salt with iodine — now adopted by most countries — is a feasible, inexpensive, and effective method to eliminate iodine deficiency in a population (14). Fortification of milk with vitamin D has helped eliminate rickets in children (10). The addition of iron and B vitamins (thiamin, riboflavin, niacin) to flour and bread products — originally done in the 1940s in the US — has improved micronutrient status among Americans. More recently, in 1998, the US government mandated that refined grain products also be fortified with folic acid. Consequently, folate status in the US population has improved (15), and the prevalence of neural tube defects in newborns has been dramatically reduced (see the article on Folate).

Overall, fortified and enriched food help Americans — both adults and children — meet dietary requirements of many micronutrients, especially folate, niacin, riboflavin, thiamin, vitamin A, vitamin D, and iron (see Table 3) (16). Along with other enriched grain products, fortified, ready-to-eat cereal represents an important source of micronutrients for children and adolescents (5, 17, 18), as well as adults (4, 17), especially the B vitamins, vitamin A, iron, and zinc.

Table 3. NHANES 2003-2006 (n=16,110): Significance of Micronutrient Intake from Fortified and Enriched Food by US Residents (≥2 Years) (16)
    Fortified and/or Enriched Food
Nutrient Average Total Daily Intake Average Daily Intake Contribution to Total Intake
 Folate 401 μg DFE 200 μg DFE 50%
 Niacin 24.3 mg 6.9 mg  28%
 Riboflavin  2.3 mg  0.6 mg  25%
 Thiamin 1.7 mg  0.7 mg  45%
 Vitamin A 602 μg RAE  185 μg RAE  31%
 Vitamin B6 1.9 mg 0.4 mg  19%
 Vitamin B12  5.3 μg  1 μg  18%
 Vitamin C  86.6 mg  13.5 mg  16%
 Vitamin D 4.9 μg 2.9 μg  59%
 Vitamin E*  6.9 mg  0.4 mg  6%
 Vitamin K 85.4 μg 1.1 μg  1%
 Calcium  940 mg  55.3 mg 6%
 Copper  1.3 mg  0.04 mg  3%
 Iron  15.8 mg  5.9 mg  38%
 Magnesium  277 mg  10.5 mg 4%
 Phosphorus  1.3 g  0.031 g 2%
 Potassium  2.6 g  0.02 g 0.8%
 Selenium  107 μg  0.7 μg <1%
 Zinc  12.1 mg  1.2 mg 10%
*α-tocopherol
Abbreviations: DFE, dietary folate equivalents; RAE, retinol activity equivalents

Both the Dietary Guidelines for Americans (1) and the position statement of the Academy of Nutrition and Dietetics (12) recognize the importance of fortification in improving micronutrient status and decreasing the prevalence of micronutrient inadequacies in the population. However, there is a general concern that food fortification can result in excessive intakes of micronutrients and potential toxicities. Some analyses of NHANES data have looked at the percent of the population with nutrient intakes in excess of the UL, but nutrient intake from fortified food cannot be directly assessed. When accounting for intake from fortified and enriched food, an analysis of data from NHANES 2003-2006 found that the prevalence of intakes greater than or equal to the UL was very low (<1%) among adults for all micronutrients examined (16). Among children ages 2-18 years, when accounting for intake from fortified and enriched food, the prevalence of intakes greater than or equal to the UL was 18.0% for zinc, 5.7% for vitamin A, 4.0% for folate, 3.7% for niacin, and 2.9% for both copper and selenium (16). It has been argued that the UL for young children is set too low for certain nutrients (i.e., zinc, vitamin A, and folate) due to a lack of data on the threshold for adverse effects in children, the use of large uncertainty factors, and inappropriate extrapolations from the UL in adults to the UL in children (19). More generally, some have pointed out that the dose-response curves needed for risk assessment have not been done for many micronutrients, making it impossible to infer meaning from the percent of the population with intakes in excess of the UL (13). Nevertheless, these data may inform decisions of food fortification with micronutrients.

Micronutrient Supplements

Even when accounting for intake from fortified food, which is quite significant for some nutrients (see Table 3 above), the prevalence of micronutrient inadequacies (i.e., intakes below the estimated average requirement [EAR]) is still quite high for some micronutrients (see Tables 2 and 3 in the article on Micronutrient Inadequacies in the United States). For example, NHANES data found that when accounting for micronutrient intakes from all sources, including fortified and enriched food, more than 90% of US adults still had intakes less than the EAR for vitamins D and E, 61% for magnesium, 51% for vitamin A, 49% for calcium, and 43% for vitamin C (16). Moreover, only 2% and 39% of US adults had intakes greater than the recommended adequate intake (AI) for vitamin K and potassium, respectively (16). Low micronutrient intakes were also prevalent among children ages 2 to 18 years, especially for vitamins D, E, and K, as well as the minerals, calcium and magnesium (16).

Consuming an energy-rich, nutrient-poor diet may lead to a state of "hidden hunger," where micronutrient inadequacies are present despite adequate or excessive provision of calories (20). Such micronutrient inadequacies may increase one’s risk for various chronic diseases, such as osteoporosis, cardiovascular disease, and cancer (21-23). Marginal or subclinical micronutrient deficiencies have also been linked to general fatigue (24), impaired immunity (see the article on Immunity) (25), and adverse effects on cognition (see the article on Cognitive Function) (26). In addition to adhering to a healthy eating pattern and including some fortified foods in the diet, micronutrient supplementation can increase intake of underconsumed nutrients in the population and help fill nutritional gaps. Both the Dietary Guidelines for Americans and the American Dietetic Association acknowledge that micronutrient supplementation can help some individuals meet their nutritional needs (1, 27).

Multivitamin/mineral supplements

A multivitamin/mineral (MVM) supplement is generally a dietary supplement that contains about 100% of the Daily Value (DV) of most micronutrients. However, there are no standardized definitions for MVMs, and the composition of marketed MVM products varies widely (e.g., some contain non-nutrient ingredients like botanicals) (28). No MVM supplement contains the DV for calcium, magnesium, potassium, or phosphorus because the resulting pill would be too bulky. The US FDA recently updated the DVs to be in line with the current dietary intake recommendations (i.e., the RDA or AI) of the Food and Nutrition Board (FNB) of the National Academy of Medicine (29). However, supplement labels may not yet reflect these changes.  

Because micronutrient requirements differ by gender and life stage, several MVM products currently on the market are formulated for specific subpopulations, i.e., for young men, young women, older adults, or children. MVMs marketed to young women generally contain iron, while many of those marketed to postmenopausal women and men typically do not.

Patterns of use

Use of nutritional supplements is common in the United States, with MVMs being the most popular type of dietary supplement. NHANES 2011-2012 found that 31% of US adults take a MVM supplement, defined as a supplement containing at least 10 micronutrients (30). Dietary supplement use is generally more prevalent among females, non-Hispanic whites, older adults, and individuals with greater formal education (30-33). Supplement use is also more common among those with a lower body mass index (BMI) and higher levels of physical activity (reviewed in 34); MVM users also more likely rate their health as excellent or very good (35, 36). A few studies have found that supplement users in general (33, 37, 38) or MVM users in particular (39, 40) are more likely to have healthier diets, including higher intakes of some micronutrients, suggesting that those who do not take MVMs may be the ones who would benefit the most from supplementation. NHANES 2007-2010 (11,956 survey respondents) reported that Americans take MVMs mainly to "improve overall health" but also to "supplement the diet" (34). In a separate survey of 2,159 US adults — funded by the Council for Responsible Nutrition — 87% of survey respondents agreed that MVMs can "help people meet nutrient needs that can’t be met through food alone" (41).

Role in filling nutritional gaps

Several studies have shown that MVM use is associated with increased micronutrient intake (42-45), suggesting that an MVM can help fill nutritional gaps and improve the prevalence of nutrient adequacy in a population. Compared to intake from food alone, use of MVMs was associated with a lower prevalence of inadequacy for several 'shortfall' (i.e., underconsumed by Americans) nutrients, including vitamins A, C, D, and E; calcium; iron; and magnesium (NHANES 2009-2012) (45). More frequent MVM use (1-10 days/month, 11-20 days/month, or ≥21 days/month vs. 0 days/month) was associated with higher average micronutrient intakes and lower prevalence of micronutrient inadequacies; these associations were stronger with more frequent MVM use (45). Moreover, an analysis from NHANES 2009-2012 that stratified the data by ethnicity found that taking dietary supplements, including MVMs, was associated with a lower prevalence of inadequacies for vitamins D and E across all ethnicities examined (Non-Hispanic white, non-Hispanic black, Hispanic, and Non-Hispanic Asian) (44). Improvements of intakes of other nutrients (i.e., calcium; magnesium; vitamins A, B6, and C; folate) were also seen with supplement use, but this varied with ethnicity — the prevalence of micronutrient inadequacy for all of these nutrients was lower with supplement use in Non-Hispanic whites (44), likely due to the fact that supplement use is more common among this ethnicity.

Biomarkers of nutrient intake (e.g., serum concentrations of a vitamin) more objectively assess nutrient body status compared to dietary surveys of self-reported intake (see Nutritional Biomarkers in the article on Micronutrient Inadequacies in the US Population). An analysis of biomarker data from NHANES found that MVM use was associated with a 58%-69% lower risk of deficiency in vitamins B6, B12, C, and D; however, MVM use was not associated with risk of iron deficiency in this analysis (45). It is important to note that data from NHANES are cross-sectional in nature and thus cannot show that MVM supplementation causes improvements in micronutrient status. For example, supplement users may have healthier diets than non-users. One analysis of NHANES 2003-2006 data (n=8,860) found that supplement users had higher dietary intakes of select micronutrients than non-users (vitamin A, folate, and vitamin E; vitamin K in men only; and vitamins C and D in women only), but both groups had a similar prevalence of micronutrient inadequacies (37). Moreover, average total intakes of vitamins (folate; vitamins A, B6, B12, C, D, E, and K) among supplement users — intake from food and supplemental sources — were significantly higher than average intakes from food alone in this group (37), suggesting that dietary supplement use does indeed help to improve micronutrient status. Compared to non-users, users of supplements had a lower prevalence of vitamin inadequacy for every vitamin examined, especially for vitamin E (5% vs. 96%), vitamin D (25% vs. 96%), vitamin A (2% vs. 58%), and vitamin C (3% vs. 48%) (37). Further, several clinical trials have found that multivitamin supplementation improves status of various micronutrients, including folate (46-49), vitamins B6 (47, 50), B12 (46-50), C (47), D (47, 48), and E (47).

While many MVMs on the market contain most micronutrients, some nutrients are not typically included in MVMs or included only at a small percentage of the recommended amount. For example, no MVM contains the recommended amount of calcium, magnesium, potassium, or phosphorus since the resulting pill would be too bulky; vitamin K and choline may not be included in MVMs. Many of these nutrients — calcium, magnesium, potassium, vitamin K, and choline — are underconsumed by the US population (called 'shortfall nutrients'), and the Dietary Guidelines label calcium and potassium as 'nutrients of public health concern' because inadequate intakes are linked to specific health concerns in the population (osteoporosis for calcium and hypertension and cardiovascular disease for potassium) (1). An overall healthy diet (see Healthy Eating above) that is abundant in fruit, vegetables, and whole grains and includes dairy or fortified sources of calcium is thus key to meeting requirements of these nutrients. Additionally, vitamin D is of particular concern because the vitamin is found only in a few foods, mainly fatty fish, and may not be included at adequate amounts in MVMs. Sunlight is the primary source of vitamin D. Some good sources of nutrients that are often not present in MVMs at recommended levels are listed in Table 4 (see also LPI's "Micronutrients for Health" handout and the "Sources" section in articles on specific vitamins or minerals). While taking a daily MVM can significantly improve micronutrient intake and help fill nutrient gaps, it is important to be cognizant of any remaining nutrient shortfalls.

Table 4. Some Food Sources of "Underconsumed Nutrients" Typically Not Present in MVMs at Recommended Amounts
Micronutrient Food Serving Size Nutrient Content
 Calcium yogurt 8 oz 415 mg
sardines, canned 1 can (3.75 oz) 351 mg
cheddar cheese 1.5 oz 303 mg
milk 1 cup 305 mg
orange juice, fortified 6 fl oz 259 mg
 Magnesium cereal, all bran ½ cup 112 mg
brown rice, medium-grain, cooked 1 cup 86 mg
fish, mackerel, cooked 3 oz 82 mg
almonds 1 oz 77 mg
spinach, frozen, cooked ½ cup 78 mg
 Potassium potato, baked with skin   1 medium 926 mg
banana 1 medium 422 mg
kidney beans, red, canned ½ cup 332 mg
pinto beans, canned ¼ cup 331 mg
prunes (died plums) ¼ cup 318 mg
tomato, raw 1 medium 292 mg
orange juice 6 fl oz 237 mg
 Vitamin D pink salmon, canned 3 oz 11.6 µg (465 IU)
sardines, canned 1 can (3.75 oz) 4.5 µg (178 IU)
orange juice, fortified 1 cup 2.5 µg (100 IU)
milk, fortified 1 cup 2.5 µg (98 IU)
egg yolk 1 large 0.9 µg (37 IU)
 Vitamin K (phylloquinone) kale, raw 1 cup 472 µg
broccoli, cooked 1 cup 220 µg
spinach, raw 1 cup 145 µg
leaf lettuce, green, raw 1 cup 46 µg
 Choline wheat germ 1 cup 202 mg
egg, boiled 1 large 147 mg
salmon, pink, canned 3 oz 75 mg
chicken breast 3 oz 73 mg
broccoli, boiled 1 cup 63 mg
Potential use in chronic disease prevention

Micronutrient inadequacies may increase susceptibility to illness and chronic disease. However, the majority of studies looking at MVM supplementation and chronic disease endpoints, including cardiovascular disease, cancer, and age-related eye diseases, have reported no significant effect or association (reviewed in 51; see the Highlight for additional references).

HIGHLIGHT: REFERENCES ON MVMS AND CHRONIC DISEASE PREVENTION
  • Angelo G, Drake VJ, Frei B. Efficacy of multivitamin/mineral supplementation to reduce chronic disease risk: a critical review of the evidence from observational studies and randomized controlled trials. Crit Rev Food Sci Nutr. 2015;55(14):1968-1991. (51)
  • Biesalski HK, Tinz J. Multivitamin/minerals supplements: rationale and safety — a systematic review. Nutrition. 2017;33:76-82. (52)
  • Comerford KB. Recent developments in multivitamin/mineral research. Adv Nutr. 2013;4(6):644-656. (53)
  • Macpherson H, Pipingas A, Pase MP. Multivitamin-multimineral supplementation and mortality: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2013;97(2):437-444. (54)
Safety

Information on the safety of MVMs comes from randomized controlled trials of long-term supplementation. The Physicians’ Health Study II (PHS II) — the longest (median of 11.2 years) and largest randomized controlled trial in healthy individuals to date — found MVM supplementation increased the risk of only two minor adverse effects: skin rashes and epistaxis (nosebleeds) (55). No effect was found for fatigue, drowsiness, migraine, skin discoloration, or gastrointestinal tract symptoms; a reduction in hematuria (blood in the urine) was noted with MVM supplementation (55). Other smaller randomized controlled trials of shorter duration have not reported serious adverse effects of MVM supplementation (reviewed in 52), but adverse effects are not commonly addressed in such trials. Moreover, MVM supplementation was not linked with an increase in all-cause mortality in a meta-analysis of 21 randomized controlled trials of MVM supplementation of at least one year in duration (54). No effect of MVM supplementation on vascular-related mortality (10 trials) or cancer-related mortality (9 trials) was found in this meta-analysis (54). Another meta-analysis that included prospective cohort studies, in addition to randomized controlled trials, reported similar results (56).

Thus, MVMs are generally considered as safe in healthy individuals because they contain amounts of micronutrients that approximate or equal the DVs. For adults, the DV for most micronutrients is considerably lower than the tolerable upper intake level (UL) — "the highest level of daily intake of a specific nutrient likely to pose no risk of adverse health effects in almost all individuals of a specified age" (57). Intake of any micronutrient from food, fortified food, and supplements should not chronically exceed its UL (58). Some analyses of NHANES data have looked at the proportion of the US population with nutrient intakes in excess of the UL when accounting for intake from all sources — food, including fortified and enriched food, and dietary supplements. In a recent report using data from NHANES 2009-2012, adults (≥19 years) who frequently used MVMs (≥21 days/month) had a 4.1% prevalence of total intakes above the UL for calcium and folate, 3.6% for zinc, and 2.9% for iron (45). Micronutrient intakes above the UL are more common among children. An NHANES 2003-2006 analysis of data in children ages 2-18 years found that the prevalence of total micronutrient intakes greater than or equal to the UL was 24% for zinc, 16% for niacin, and 15% for vitamin A and folate (16). As stated above, some have expressed concern that the UL for children is set too low for certain nutrients (i.e., zinc, vitamin A, and folate) due to the use of inadequate data on the threshold for adverse effects in children, the use of large uncertainty factors, and inappropriate extrapolations in derivation of the UL (19).

More generally, some have pointed out that the dose-response curves needed for risk assessment of individuals in a specific gender and life stage group have not been done for most micronutrients, and for these nutrients, estimating an intake level that is associated with risk of adverse effects is not possible (13). Thus, for some nutrients, one cannot label intakes greater than the UL as "excessive" (13). The nutrient that is overconsumed by the US population, sodium, is not included in MVMs — sodium intake comes from dietary sources, mainly processed food (1).

Thus, it is important to look for an MVM that contains no more than recommended amounts of vitamins and minerals (i.e., no more than 100% of the DV or RDA) and avoid products labeled as "high potency," "ultra potency," or "mega" as such supplements could contain excessive amounts of some micronutrients. Although dosages of micronutrients included in most MVMs are generally safe, some supplements may provide excessive vitamin A or iron. For example, daily use of a MVM supplement can supply as much as 5,000 IU/day of vitamin A as retinol, an amount that has been associated with bone fractures in older adults. For this reason, the Linus Pauling Institute (LPI) recommends that adults take a MVM supplement that provides no more than 2,500 IU (750 μg) of preformed vitamin A (usually labeled vitamin A acetate or vitamin A palmitate) and no more than 2,500 IU of additional vitamin A as β-carotene. Additionally, because excess preformed vitamin A (retinol) during pregnancy is known to cause birth defects and because a number of foods in the US are fortified with retinol, LPI recommends that pregnant women avoid a MVM or prenatal supplements that contain more than 5,000 IU (1,500 μg) of vitamin A in the form of retinol. Moreover, children should not be given a MVM supplement that contains more retinol than the RDA for their age group (see the Table 1 in the article on vitamin A). Men and postmenopausal women are not at risk for iron deficiency, and excess iron from the diet and supplements can have adverse effects. Therefore, LPI recommends that men and postmenopausal women take a MVM supplement without iron. A number of MVMs formulated specifically for men or for those over 50 years of age do not contain iron. Even though MVM supplements are safe for most people, individuals should discuss the use of all nutritional supplements with a competent healthcare professional. People taking pharmaceutical drugs to treat certain medical conditions need to be aware of any potential drug-nutrient interactions; some potential interactions are listed in the article on Subpopulations at Risk for Micronutrient Inadequacy or Deficiency: see the section on Those Taking Drugs Known to Interact with Nutrients.

Another safety issue concerns the quality of commercially available MVM supplements. In 2007, the US Food and Drug Administration established standards of current good manufacturing practices (CGMPs), which ensure dietary supplements meet quality standards with respect to identity, purity, strength, and composition (59). All US and foreign companies were required to comply with the CGMPs by June 2010. In addition to these government regulations, at least three independent organizations evaluate the quality of dietary supplements on a fee basis: NSF International, US Pharmacopeia, and ConsumerLab.com. Supplement labels of approved products can bear the certification mark, verification mark, or seal of approval of these organizations. However, many products that are in full compliance do not carry such certification marks on their labels, and absence of a seal does not mean lack of adherence to CGMP or other regulations.

Conclusion

Nutrition education campaigns have yet to convince people to make better food choices: The reality is that most Americans do not follow a healthy eating pattern and instead eat an energy-rich, nutrient-poor diet (1). Given the facts that dietary habits are difficult to change and that micronutrient inadequacies remain prevalent among the US population, a daily multivitamin/mineral (MVM) — a dietary supplement that contains about 100% of the Daily Value (DV) of most vitamins and nutritionally essential minerals — is a sensible public health recommendation. As part of its Rx for Health, the Linus Pauling Institute recommends a daily multivitamin/mineral (MVM) supplement as nutritional insurance to help meet micronutrient needs. MVMs are a simple, inexpensive, and safe way to help fill nutritional gaps and improve micronutrient status. While the specific consequences of chronic micronutrient inadequacies are difficult to document, it is prudent and affordable to ensure adequacy for health by taking a daily MVM supplement.

Other nutrient supplements

Other micronutrient supplements may be needed if intake recommendations are not being met by a combination of dietary sources and the MVM. However, one must first assess his/her actual micronutrient intake and determine if a micronutrient gap exists. As mentioned above, some micronutrients (e.g., calcium, magnesium, potassium) are not included in MVMs at recommended intake levels, and consuming foods rich in these nutrients is recommended (see the discussion above and Table 4). A number of other factors, including life stage, disease status, and risk profile, affect one’s decision regarding micronutrient supplementation (51). For example, it is widely recommended that all women capable of becoming pregnant take at least 400 μg/day of supplemental folic acid; more information on micronutrients during pregnancy can be found in the Pregnancy In Brief and Pregnancy and Lactation articles.

In addition to a daily MVM, the Linus Pauling Institute recommends a few additional micronutrient supplements:

Vitamin D

The Linus Pauling Institute recommends that generally healthy adults take 2,000 IU (50 μg) of supplemental vitamin D daily. Most multivitamins contain 400 IU (10 μg) or 600 IU (15 μg) of vitamin D, and single-ingredient supplements are available for additional supplementation. Sun exposure, diet, skin color, and body mass index (BMI) have variable, substantial impact on body vitamin D levels. To adjust for individual differences and ensure adequate body vitamin D status, the Linus Pauling Institute recommends aiming for a serum 25-hydroxyvitamin D concentration of at least 30 ng/mL (75 nmol/L).

The American Academy of Pediatrics currently suggests that all infants, children, and adolescents receive 400 IU of supplemental vitamin D daily (60). Consistent with the recommendations of the Endocrine Society (61), the Linus Pauling Institute recommends daily intakes of 400 to 1,000 IU (10 to 25 µg) of vitamin D in infants and 600 to 1,000 IU (15 to 25 µg) of vitamin D in children and adolescents. Given the average vitamin D content of breast milk, infant formula, and the diets of children and adolescents, supplementation may be necessary to meet these recommendations. (More on vitamin D)

Vitamin C

Studies conducted at the National Institutes of Health showed that plasma and circulating cells in healthy, young subjects attained near-maximal concentrations of vitamin C at a dose of 400 mg/day (62, 63). Because of the high benefit-to-risk ratio of vitamin C supplementation, and to ensure tissue and body saturation of vitamin C in almost all healthy people, the Linus Pauling Institute recommends a vitamin C intake of at least 400 mg daily for adult men and women. Consuming at least five servings (2½ cups) of fruit and vegetables daily provides about 200 mg of vitamin C. Most multivitamin/mineral supplements provide 60 to 90 mg of vitamin C. To meet the Institute’s recommendation, supplemental vitamin C in two separate 250-mg doses taken in the morning and evening is recommended. (More on vitamin C)

Vitamin B12

A varied diet should provide enough vitamin B12 to prevent deficiency in most individuals 50 years of age and younger. Strict vegetarians and women planning to become pregnant should take a daily multivitamin supplement or eat fortified cereal, which would ensure a daily intake of 6 to 30 µg of vitamin B12 in a form that is easily absorbed. Because vitamin B12 malabsorption and vitamin B12 deficiency are more common in older adults, the Linus Pauling Institute recommends that adults older than 50 years take 100 to 400 µg/day of supplemental vitamin B12. Supplemental vitamin B12 is also recommended for patients taking medications that interfere with its absorption (see Drug interactions in the separate article on vitamin B12). (More on vitamin B12)

Conclusion

Consumption of an energy-rich, nutrient-poor diet — the current dietary pattern in the United States — results in suboptimal health and increases risk of chronic disease. Despite decades of public health messages to eat a balanced diet, overall adherence to the Dietary Guidelines for Americans (1) is low. As a result, micronutrient inadequacies, especially vitamins A, C, D, and E; calcium; and magnesium, are quite prevalent in the population among various age groups and ethnicities (33, 44). Certain subgroups of the population are at a heightened risk of micronutrient deficiencies due to several factors, including life stage, disease status, pharmaceutical use, and various lifestyle choices. While debate about the optimal diet for health continues (64), there is ample evidence to support the benefits of following a healthy eating pattern like those discussed in the Dietary Guidelines for Americans — plant-based diets abundant in fruit, vegetables, legumes, whole grains, nuts, and seeds and limited in processed food. Adhering to such an eating pattern is important to obtain the nutrients needed for optimal health and to help prevent chronic disease throughout the lifespan. Consuming fortified food and taking a daily multivitamin/mineral supplement can help fill micronutrient gaps in the diet. Depending on diet and life stage, additional single-nutrient supplements like vitamins B12, C, and D may be needed to reach micronutrient intake recommendations. Many studies have shown that use of dietary supplements results in improved micronutrient intake and thus decreased prevalence of micronutrient inadequacy in the population. However, supplements should not replace a healthful eating pattern; on the contrary, by definition "supplements" should be used to complement healthy eating to ensure nutrient adequacy for optimal health.


Authors and Reviewers

Written in January 2018 by:
Victoria J. Drake, Ph.D.
Linus Pauling Institute
Oregon State University

Reviewed in March 2018 by:
Balz Frei, Ph.D.
Former Director, Linus Pauling Institute
Distinguished Professor Emeritus, Dept. of Biochemistry and Biophysics
Oregon State University

The writing of this article was supported by a grant from Pfizer Inc.

Copyright 2018  Linus Pauling Institute


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