May 2016 Issue
Role of Multivitamins in Filling Nutrient Gaps
By Elizabeth M. Ward, MS, RD
Vol. 18 No. 5 P. 34
Most Americans don't meet all their daily vitamin and mineral requirements through food and could improve their health by taking a multivitamin.
Nutrition professionals most often suggest relying on food first for meeting recommended vitamin and mineral (micronutrient) intakes. However, many people in the United States have eating patterns that don't include adequate servings from all of the food groups on a regular basis to meet their needs. As a result, certain micronutrient deficiencies prevail in the general adult population.
Healthy people, especially women in their childbearing years and adults over the age of 50, may not be getting enough micronutrients for a variety of reasons.
This article will discuss ongoing micronutrient insufficiencies in the adult US population and focus on certain groups that are at particular risk of underconsuming vitamins and minerals. It also will provide suggestions for working with these clients and patients to help them meet their vitamin and mineral needs.
Poor Eating Patterns and Health
Approximately 117 million adults in the United States—one-half of the adult population—have at least one preventable chronic disease.1 Many of these conditions, including cardiovascular disease, hypertension, type 2 diabetes, and diet-related cancers, are associated with poor food choices and inadequate physical activity. While not as common as heart disease, cancer, and diabetes, other diet- and lifestyle-related health issues, including birth defects, iron-deficiency anemia, and poor bone health, are cause for serious concern. For example, data from 2005 to 2010 show that about 10 million US adults aged 50 and older had osteoporosis, and another 43 million had low bone mass.1
The 2015–2020 Dietary Guidelines for Americans (2015 DGA), a joint project of the US Department of Health and Human Services and the USDA, are designed to help Americans aged 2 and older make healthful eating choices. Improving eating patterns is greatly emphasized in the 2015 DGA. One of the prevailing themes is that people eat foods and nutrients in combinations, called patterns, and that the components of those combinations, including vitamins and minerals, can have interactive and potentially cumulative effects on health, including contributing to, or preventing, chronic disease.1
A balanced and varied eating pattern contributes to meeting micronutrient needs. However, typical eating patterns in the United States don't align with the dietary guidelines.2 Just 58% of the population aged 2 and older adhere to the eating suggestions in the 2010 DGA, as measured by Average Total Healthy Eating Index-2010 scores.1 Indeed, ≤25% of Americans aged 1 and older eat adequate amounts of fruits, vegetables, and dairy. Inadequate intake of fruits, vegetables, whole grains, and fat-free and low-fat dairy foods increases the potential for insufficient intake of several vitamins and minerals.1 In addition to consuming fewer nutrient-dense foods than recommended, many individuals consume excess sodium, saturated fat, refined grains, and added sugars.1
Micronutrient Shortfalls in the US Diet
According to the 2015 DGA, Americans aged 2 and older underconsume vitamins A, D, C, and E; choline; and potassium. In addition, adolescent females and women aged 19 to 50 don't get enough iron in their diet. Dietary fiber intake also is insufficient.1
The assessment of nutrient shortfalls in the 2015 DGA differs from the data presented in the 2015 Dietary Guidelines Advisory Committee (DGAC) report. The 2015 DGA are based on the report of the 2015 DGAC, a federal advisory group responsible for conducting a robust review of the body of scientific evidence.2 The DGAC report includes folate and magnesium as shortfall nutrients in the general population over the age of 2, but the 2015 DGA do not.2
Micronutrient shortfalls are an ongoing problem among those living in the United States, as data from 2003 to 2010 show. The 2003–2006 National Health and Nutrition Examination Survey (NHANES) found that high percentages of the US population had total usual intakes from all food sources (excluding supplements) below the Estimated Average Requirement (EAR) for vitamins A, C, D, and E (45%, 37%, 93%, and 91%, respectively); calcium (49%); and magnesium (55%).3 An analysis of NHANES data from 2007 to 2010 found similar results; people in the United States had total usual intakes from all food sources (excluding supplements) below the EAR for vitamins A, C, D, and E (43%, 39%, 94%, and 89%, respectively); calcium (44%); and magnesium (52%).4
Nutrients of Concern in the 2015 DGA
Of the underconsumed micronutrients, only calcium, potassium, and vitamin D are considered nutrients of public health concern for the general population (including children) in the 2015 DGA, as low intakes of these nutrients are associated with health conditions. Calcium, vitamin D, and potassium also were the only micronutrients identified as nutrients of concern for the general population in the 2010 DGA and in the 2005 DGA.5,6
Iron is a nutrient of public health concern in the 2015 DGA for young children, women capable of becoming pregnant, and pregnant women.1 Iron also was a nutrient of public health concern in the 2005 and 2010 versions of the DGA.5,6
The 2015 DGA doesn't identify folic acid as a nutrient of public health concern for women who are capable of becoming pregnant, although the nutrient was called out in the 2005 DGA and the 2010 DGA as such.1,5,6 In addition, vitamin B12 is identified as a nutrient of concern for people older than age 50 in the 2005 DGA and the 2010 DGA, but not in the 2015 version.5,6 These differences warrant further discussion.
It's unclear why there was no mention of vitamin B12 in the 2015 DGAC report and in the 2015 DGA. The 2005 and 2010 DGA referred to vitamin B12 as a nutrient of concern in people older than age 50 and recommended that individuals aged 50 and older consume foods with added vitamin B12, such as fortified cereals or dietary supplements.5,6 This advice echoes the Institute of Medicine's recommendation for B12, which states that adults older than age 50 should obtain most of their vitamin B12 requirements from vitamin supplements, fortified foods, or a combination.7
Atrophic gastritis is the primary reason for the recommendation that older people should obtain the majority of their vitamin B12 in the synthetic form. The condition affects 10% to 30% of older adults, and it results in decreased absorption of naturally occurring vitamin B12 from food.7 Atrophic gastritis is simply addressed with the use of vitamin supplements, vitamin B12-fortified foods, or both. Although individuals with atrophic gastritis cannot properly absorb naturally occurring vitamin B12 present in food, most can absorb the synthetic crystalline vitamin B12 added to fortified foods and dietary supplements.7
Evidence from the Framingham Offspring Study showed that individuals who took a supplement containing vitamin B12 or consumed fortified cereal more than four times per week were much less likely to have a vitamin B12 deficiency.8 Furthermore, common over-the-counter medications may aggravate dietary vitamin B12 insufficiency. A recent study adds to the body of evidence suggesting a link between vitamin B12 deficiency and the long-term use of proton-pump inhibitors and histamine 2-receptor antagonists.9 In addition, metformin use in people with type 2 diabetes has been associated with an increase in vitamin B12 insufficiency and borderline deficiency.10
The 2015 DGA recommendation is for an intake of synthetic folic acid in addition to natural folate found in foods as part of a healthful eating pattern, but it doesn't specify folic acid as a nutrient of concern for women in their childbearing years who are capable of becoming pregnant. However, that doesn't diminish the importance of folic acid for this population.
According to the 2015 DGA, fortification of enriched grain products in the United States has successfully reduced the incidence of neural tube defects, which arise from the incomplete closure of the neural tube during pregnancy.1 The neural tube forms the spinal column and brain. Adequate intake of folic acid helps prevent neural tube defects, often during the time when a woman may not realize she's expecting.
All women capable of becoming pregnant are advised to consume 400 micrograms (mcg) of synthetic folic acid daily, from fortified foods and/or supplements.1 Many over-the-counter multivitamins contain 400 mcg of folic acid.
People at Risk of Micronutrient Insufficiencies
Anybody can have insufficient vitamin and mineral intake, but certain groups are prone to inadequate micronutrient intake. The possibility of multiple chronic vitamin and mineral shortfalls increases when people often fall into more than one of the following categories, as they often do. The following are some of the groups at particular risk of insufficient vitamin and mineral intake:
- people who avoid or restrict foods from any food group, such as enriched and fortified grain products;
- women of childbearing age;
- people on frequent low-calorie diets;
- those with a history of weight loss surgery;
- people with conditions that reduce the body's absorption of vitamins A, D, E, or K;
- people on a gluten-free diet;
- those taking medications that interfere with the absorption and/or metabolism of certain micronutrients, including those used to treat gastric reflux; and
- people older than age 50 or 70 (recommendations for intake of certain micronutrients differ at these age thresholds).
Can Small Shifts Fill Micronutrient Gaps?
In keeping with the theme of improving the US diet, the 2015 DGA emphasize that "every food choice is an opportunity to move toward a healthy eating pattern" and suggest making "small shifts" in food choices to help fill gaps in the nutrients of concern and other vitamins and minerals, as well as to decrease the intake of overconsumed components such as saturated fat, sodium, and added sugar.1
The suggestion to make small shifts in food choices (eg, choosing nutrient-dense foods within each food group more often) is helpful, actionable advice for consumers, in large part because it advocates gradual changes in eating that add up to big improvements. But some nutrition experts say the advice about bridging micronutrient gaps doesn't go far enough to support health.
"The 2015 DGA explicitly state that over 40% of the American population fails to meet the EAR for many micronutrients, but provide little guidance on how to fill these shortfalls," says researcher Jeffrey Blumberg, PhD, of Tufts University's Jean Mayer USDA Human Nutrition Research Center on Aging in Boston.
The 2015 DGA say that in some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts or that are of particular concern for specific population groups.1 For example, the guidelines advise that vitamin D supplementation is appropriate when sunshine exposure is limited, and that pregnant women may need to take an iron supplement.1
Even if people made the dietary improvements suggested in the 2015 DGA, they still may have micronutrient insufficiencies. Here's why: The 2015 DGA include eating patterns, such as the Healthy US-Style Eating Pattern, to help consumers achieve their nutrient needs. The Healthy US-Style Eating Pattern is "based on the types and proportions of foods Americans typically consume, but in nutrient-dense forms and appropriate amounts," and is designed to meet nutrient needs without exceeding calorie intake requirements or the limits for overconsumed nutrients.1 Yet, the 2015 DGA acknowledge that the Healthy US-Style Eating Pattern fails to meet the Recommended Dietary Allowance (RDA) or Average Intake (AI) for vitamin D, vitamin E, choline, and potassium for many or all age-sex groups.1
Furthermore, the 2015 DGA state that, "In most cases, an intake of these nutrients below the RDA or AI is not considered to be of public health concern." This statement appears to be at odds with the identification of vitamin D and potassium as nutrients of public health concern in the 2015 DGA.
Bridging Micronutrient Gaps
Research suggests consumers have made few improvements in their food choices in recent decades.2 Using history as a guide, it's reasonable to assume that most Americans won't make the "small shifts" in eating patterns recommended in the 2015 DGA, at least not right away.
"It's difficult to believe that a large majority of Americans will change their food choices to the point of closing gaps in so many micronutrients any time soon," Blumberg says. "Until consumers make more healthy food choices on a daily basis, they will miss out on several vitamins and minerals that they need for good health, and that help prevent and manage chronic conditions."
The DGA suggest a more balanced and varied diet as a solution for helping to fulfill micronutrient quotas.1 RDs are skilled at creating eating patterns based on clients' and patients' needs. But sometimes food can't meet every nutrient need.
"A daily multivitamin likely has a role in filling in micronutrient gaps, especially when deficiency or insufficiency may be relevant," says Howard Sesso, ScD, MPH, an associate professor of epidemiology at the Harvard T. H. Chan School of Public Health. Sesso is coauthor of the Physicians' Health Study II, the only large-scale randomized clinical trial to test the health effects of a multivitamin similar to the ones most people take.
Dietary supplements, such as multivitamins, are exactly what their name implies, and aren't considered substitutes for healthful eating patterns. Many multivitamin supplements provide adequate folic acid, iron, vitamin B12, and vitamin D, but they don't contain RDA levels for potassium and provide only a portion of the recommended daily intake for calcium. Minerals such as potassium and calcium are difficult to incorporate into a typical multivitamin due to product development challenges. As a result, multivitamins can't be considered a sole, or even a significant, source of calcium and potassium.
Nutritional inadequacies are less common among those who take multivitamin supplements, not only because of the nutrients they provide but also possibly because users of multivitamins tend to be better educated, more active, and less likely to be smokers—factors that often are associated with eating more nutritious foods and an overall more healthful lifestyle.4 NHANES data show that men, women, and children who used multivitamin supplements had higher dietary intake of key micronutrients than nonusers.4 In another national US study, regular use of supplements resulted in an estimated ≥75% decrease in the proportion of older persons with inadequate micronutrient intakes.11
The potential benefits of multivitamin supplements likely outweigh any risk in the general population and may be particularly beneficial for older people. "Importantly, no risks have been identified to date with taking a common multivitamin broadly focused on essential vitamins and minerals," Sesso says.
— Elizabeth M. Ward, MS, RD, is a freelance writer and author of several books. She blogs at www.betteristhenewperfect.com and serves as a consultant for Pfizer.
1. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans 2015–2020: Eighth Edition. http://health.gov/dietaryguidelines/2015/guidelines/. Published January 7, 2016.
2. US Department of Agriculture, US Department of Health and Human Services. Scientific Report of the 2015 Dietary Guidelines Advisory Committee. http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf. Published February 2015.
3. Fulgoni VL 3rd, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: where do Americans get their nutrients? J Nutr. 2011;141(10):1847-1854.
4. Wallace TC, McBurney M, Fulgoni VL 3rd. Multivitamin/mineral supplement contribution to micronutrient intakes in the United States, 2007-2010. J Am Coll Nutr. 2014;33(2):94-102.
5. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2010: 7th ed. http://www.cnpp.usda.gov/sites/default/files/dietary_guidelines_for_americans/PolicyDoc.pdf. Published December 2010.
6. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2005: 6th ed. http://www.cnpp.usda.gov/sites/default/files/
dietary_guidelines_for_americans/2005DGPolicyDocument.pdf. Published 2005.
7. Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academies Press; 1998.
8. Tucker KL, Rich S, Rosenberg I, et al. Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study. Am J Clin Nutr. 2000;71(2):514-522.
9. Lam JR, Schneider JL, Zhao W, Corley DA. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013;310(22):2435-2442.
10. Reinstatler L, Qi YP, Williamson RS, Garn JV, Oakley GP Jr. Association of biochemical B12 deficiency with metformin therapy and vitamin B12 supplements: the National Health and Nutrition Examination Survey, 1999-2006. Diabetes Care. 2012;35(2):327-333.11. Sebastian RS, Cleveland LE, Goldman JD, Moshfegh AJ. Older adults who use vitamin/mineral supplements differ from nonusers in nutrient intake adequacy and dietary attitudes. J Am Diet Assoc. 2007;107(8):1322-1332.