The American Nutrient Gap: And How Vitamin and Mineral Supplements Can Help Fill It

Sponsored by the Campaign for Essential Nutrients

While physicians and their patients increasingly focus on the importance of a healthful, balanced diet, paradoxically, data show diets of more than 90% of Americans fall short in providing the Estimated Average Requirement (EAR) or Adequate Intake (AI) for one or more vitamins and minerals. This “vitamin and mineral gap” is particularly striking because EARs are a lower “nutritional bar” compared to the Recommended Dietary Allowances (RDAs) (see Box). The Gap has been shown consistently over the years in the National Health and Nutrition Examination Survey (NHANES)  analyses.^1,2,3,4,5

About Dietary Reference Intakes (DRIs)

In the past, the recommended nutrient intakes from the Institute of Medicine (IOM) – the Recommended Dietary Allowances (RDAs) in the United States and Recommended Nutrient Intakes (RNIs) values in Canada – focused primarily on preventing nutritional deficiencies. In 1994, the scope expanded to optimizing health, preventing disease, and avoiding excessive nutrient intakes.¹⁰ These new recommendations, the DRIs, include:⁸

• EARs, the average intake level estimated to meet the requirements of half of the healthy individuals in a group (based on life stage and gender)

• RDAs, the average intake level sufficient to meet the requirements of nearly all (97-98 percent) of healthy individuals in a group

• Adequate Intakes (AIs), the recommended average intake level based on approximations or estimates of intake by a group or groups of healthy people and that are assumed to be adequate; used when an RDA has not been determined

• Tolerable Upper Intake Levels (ULs), the highest average daily nutrient intake likely to pose no risk of adverse effects to almost all individuals in the general population

Additionally, Daily Values (DVs), used on food and dietary supplement labels to indicate nutrient contents as a percent of daily needs, were established by the U.S. Food and Drug Administration (FDA) and initially based primarily on the highest of the 1968 (and later, 1989) RDAs for people four years of age and older, excluding pregnant and lactating women, and a daily 2,000-calorie diet. The reference values used for labeling the percent DVs for vitamins and minerals are termed Reference Daily Intakes (RDIs). Over the years, RDIs for additional vitamins and minerals have been established, and FDA has recently updated the DVs.¹¹

One such analysis, based on NHANES nutrient intake data (2007-2010, n = 16,444), shows that, among U.S. residents four or more years of age, 100%, 94%, 92% and 89% consume less than the EAR or AI for potassium (AI), vitamin D, choline (AI) and vitamin E, respectively, from food alone (see Figure). ¹

Consistent with these findings, the most recent Dietary Guidelines for Americans, released January 6, 2016 by the U.S. Departments of Health and Human Services and of Agriculture, identified potassium, dietary fiber, choline, magnesium, calcium, and vitamins A, D, E, and C as nutrients, “consumed by many individuals in amounts below the Estimated Average Requirement or Adequate Intake levels.” ⁶

Low intakes of vitamins and minerals can increase the risk for nutritional deficiencies. Deficiencies for many (but not all) vitamins and minerals are defined by cut points in biomarkers, usually some level of the nutrient or a related metabolite in the serum or urine. While less than 10% of the overall U.S. population has nutrition deficiencies, the prevalence varies considerably by age, gender and race/ethnicity, and is as high as nearly one third in certain population groups. The following are several examples from the Center for Disease Control (CDC) Second National Report on Biochemical Indicators of Diet and Nutrition:⁷

• 30 million Americans (10.5%) have a vitamin B6 deficiency, with higher rates among Non-Hispanic blacks (15.7%) and those 60+ years old (16%).⁷ Vitamin B6 deficiency is associated with microcytic anemia, dermatitis (scaling on the lips and cracks at the corners of the mouth), glossitis (swollen tongue), depression and confusion, and weakened immune function. ^8,9  Individuals with borderline vitamin B6 concentrations or mild deficiency might have no signs or symptoms for months or years.

• 23 million Americans (8.1%) have severe vitamin D deficiency.^† Non-Hispanic blacks (31.1%) and Mexican-Americans (11.3%) are more likely to be vitamin D deficient compared to non-Hispanic whites (3.6%).⁷  Few foods contain vitamin D and people get it from exposure to sunlight. However, its synthesis is reduced in darkly pigmented skin and with sunscreen use.  The potential effects of vitamin D deficiency include rickets (children), osteomalacia and osteoporosis (adults), muscle weakness and compromised immune function.¹²

• 7.5 million women age 12-49 years (9.5% of that group) have low body iron status, with higher rates among Mexican Americans (13.2%) and non-Hispanic blacks (16.2%). Iron is needed for the formation of hemoglobin. Iron deficiency is linked to reduced physical capacity, poor pregnancy outcomes, and can progress to anemia if not treated.⁷

• Approximately one-third of pregnant women in the United States are marginally iodine deficient.^{7, 13} Iodine is an essential component of thyroid hormones, which play a key role in normal growth and development and regulate critical enzymes and metabolic processes. Iodine deficiency disorders include mental retardation, hypothyroidism and varying degrees of growth and developmental abnormalities in children.⁸

Additional information about the functions and effects of deficiencies of the Gap nutrients are shown in the Table at the end of this article.

Figure: Percent of U.S. Population Obtaining Less Than the EARs or AIs for Selected Nutrients From Food Alone or Food + Multivitamin/Mineral Supplements¹

Figure: Percent of U.S. Population Obtaining Less Than the EARs or AIs for Selected Nutrients From Food Alone or Food + Multivitamin/Mineral Supplements

AI: Adequate Intake; EARs: Estimated average requirements; MVMS: Multivitamin/mineral supplements.

Note: Less than 10% of individuals were below the EARs for thiamin, riboflavin, niacin, folic acid, vitamin B6, vitamin B12, iron, copper, phosphorus and selenium (not shown in Figure).

Filling the Gap

How can this vitamin and mineral gap be filled? Nutritionists and other health professionals advise patients to get the nutrients they need from their diet. Unfortunately, research shows that relying on food alone results in nutrient deficits for many Americans. Indeed, the recent Dietary Guidelines for Americans state as a goal that people should, “meet nutritional needs primarily through foods,” but also recognize vitamin and mineral supplements (VMS) are, “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.” ⁶

Data support the use of VMS in helping to fill common nutrient gaps. The analysis of NHANES data (2007-2010) ¹ described above reported vitamin and mineral intakes among U.S. residents four years and older from food alone and from food + multivitamin/mineral supplements (MVMS). Of the dietary supplements consumed, 51% were MVMS, defined as providing at least 100% of the RDA or AI for nine vitamins and minerals with defined DRI values. The analysis showed that less of the population has vitamin and mineral intakes below many EAR values when nutrient contributions from both food and MVMS were compared to contributions from food alone (Figure). The differences in the Figure between food alone vs. food + MVMS might be less than expected because the comparison was made for the entire NHANES sample, e.g., nutrient intakes from food + MVMS included those from MVMS users and non-users combined (non-users comprised about three-fourths of the 16,444 individuals in the analysis). Additionally, MVMS users were broadly defined as those who reported taking an MVMS as infrequently as just once during the 30 days prior to data collection, and so included occasional/sporadic as well as daily users.¹  Finally, many MVMS provide low or no amounts of some nutrients, such as calcium, magnesium, zinc, potassium and choline.

A number of published reports of vitamin and mineral status of Americans based on biomarker data demonstrate that, while significant portions of the population have or are at risk for deficiencies, rates of deficiencies are lower for VMS users. For example:

• NHANES data (2001-2006) show the prevalence of vitamin D deficiency, based on serum levels of 25-hydroxyvitamin D <30 nmol/L, is 14% among individuals two or more years of age who do not take a dietary supplement compared to 5% among those who do. ¹⁴

• Based on a standard definition for vitamin B12 deficiency (serum B12 < 258 pmol/L or methylmalonic acid > 0.21 μmol/L), NHANES data (1999-2002) show 38% of adults age 60 years or more are deficient, but the rate is 30% among those who took any B12-containing VMS. This definition of deficiency was also associated with significantly increased risks for peripheral neuropathy and disabilities.¹⁵

• NHANES data (2003-2004) show 7% of Americans aged 6 years or older are deficient in vitamin C, based on the standard serum concentration cut off of <11.4 μmol/L. Lower rates of deficiency are found among men and women who used any vitamin C-containing VMS compared to those who did not: 2% (both genders) vs. 16% and 11%, respectively).¹⁶

• NHANES data (2003-2006) show that, while only 1% of Americans age 20 years or more have serum levels of vitamin E meeting the criterion for clinical deficiency (α-tocopherol < 12 μmol/L), 81% of dietary supplement non-users have vitamin E “inadequacy” compared to 46% of users. In this analysis, vitamin E inadequacy was defined as a serum α-tocopherol level below that associated with consuming the EAR and with the lowest mortality rate in a major interventional trial (< 30 μmol/L).^17,18

Interestingly, supplement users obtain more vitamins and minerals from foods compared to non-users, ^3,4 so it does not appear that supplements are primarily used to compensate for poor dietary habits.¹  Dietary supplement use is also associated with moderate alcohol use, more exercise, smoking abstinence and having health insurance.¹⁹

Beyond nutritional deficiencies, low intakes of vitamins and minerals may be associated with suboptimal health. Indeed, as noted in the Box, the concept of optimizing health and preventing disease is a major underpinning for the shift, in 1994, from the RDAs to the DRIs for nutrients.⁸  The CDC’s Second National Report on Biochemical Indicators of Diet and Nutrition⁷ notes:

“…recent findings have determined that less than optimal biochemical concentrations (representing suboptimal status) have been associated with risks of adverse health effects. These health effects include cardiovascular disease, stroke, impaired cognitive function, cancer, eye diseases, poor bone health, and other conditions.”

Some studies have associated Americans’ use of dietary supplements (containing vitamins, minerals and/or herbs or other substances) with positive health indicators, for example:²⁰

• Healthier serum levels of various lipids and homocysteine

• Reduced prevalence of elevated blood pressure

• Better self-assessed health status

• Reduced markers of inflammation, including C-reactive protein and interleukin-6 ²¹

Vitamin and Mineral Supplements in Practice

Over the past several years, some studies have fueled a debate over the role of VMS in helping to prevent cardiovascular disease, cancer and other chronic diseases. While the resulting media headlines and hype may cause confusion, it is important not to lose sight of what vitamins and minerals are: essential nutrients. Solid, accumulated scientific evidence has established the indispensable biochemical and physiological functions of vitamins and minerals in the body, as well as the specific amounts needed.

Further research is needed on the effects of VMS on chronic disease risk, especially long-term epidemiological studies; the findings could help address some of the challenges identified in using chronic disease endpoints to set DRI values.²²  Nevertheless, the collective evidence to date leaves no doubt that many Americans are obtaining less than the required amounts of a number of vitamins and minerals, and that these nutritional shortfalls are associated with biomarker-defined deficiencies and inadequacies that can have serious health consequences. The evidence also shows that VMS use is associated with improved intakes of the Gap nutrients, lower rates of deficiencies and inadequacies and, in some studies, improved health status. Health professionals should bear this in mind when seeing their patients, and consider recommending ways to improve their diets, which can include taking VMS

The Campaign for Essential Nutrients is comprised of Bayer HealthCare LLC, DSM Nutritional Products, PHARMAVITE LLC. and Pfizer Inc.

Table: Vitamins and Minerals Low in Many Americans’ Diets: Functions and Effects of Deficiencies^8,9,10

Key Functions: Bone mineralization, calcium and phosphorous homeostasis; cell division, differentiation and growth; immune function; insulin secretion; blood pressure regulation; neuromuscular function.

Effects of Deficiency: Causes rickets in children and osteomalacia in adults; muscle weakness and pain; compromised immune function; bone pain; increased risk for osteoporosis.

Key Functions: Major fat-soluble antioxidant.

Effects of Deficiency: Neurologic and eye damage, red blood cell fragility, muscle weakness.

Key Functions: Eye and immune function; pre-and post-natal development; tissue growth, specialization and repair.

Effects of Deficiency:  Night blindness and other vision defects, reduced immune function.

Key Functions: Most important water-soluble antioxidant, involved in 14 biosynthetic reactions in humans and wound healing.

Effects of Deficiency: Scurvy, impaired wound healing, weakness, fatigue.

Key Functions: Required for synthesis of a number of proteins involved in normal blood clotting as well as bone formation and cell growth regulation.

Effects of Deficiency:  Impaired blood clotting, potentially manifested as nosebleeds, blood in urine and stools, and life-threatening intracranial hemorrhaging.

Key Functions: Major mineral in bones and teeth, intracellular signaling messenger, “on-off” activation of nerve, muscle and other cells, cofactor for a number of enzymes and proteins.

Effects of Deficiency: rickets in children; very low bone mineral density (osteoporosis), increased risk of fractures.

Key Functions: Involved in more than 300 metabolic reactions affecting energy production, DNA and protein synthesis, ion transport, cell signaling; also has structural functions.

Effects of Deficiency:  Reduces levels of calcium and potassium; neurologic and muscle cramps, seizures.

Key Functions: Involved in many catalytic, structural and regulatory functions.

Effects of Deficiency growth retardation, hair loss, diarrhea, eye and skin lesions, impaired appetite.

Key Functions: An electrolyte, the primary positive ion inside cells, involved in maintaining cell membrane potential.

Effects of Deficiency: fatigue, muscle weakness, cramps, cardiac arrhythmias, glucose intolerance.

Key Functions: Serves as methyl donor for various reactions; a component of neurotransmitter acetylcholine and membrane phospholipids.

Effects of Deficiency:  Liver and muscle damage.

*Begun in the 1960s, NHANES is a program of studies by the National Center for Health Statistics that assesses the health and nutritional status of a nationally representative sample of noninstitutionalized U.S. civilian residents each year.

^†The scientific/medical literature is inconsistent in defining vitamin D deficiency. Here “severe vitamin D deficiency” is defined as a 25-hydroxyvitamin D serum level < 30 nmol/L, the cut-off used by the Institute of Medicine (IOM) as the criterion for increased risk for rickets. However, the IOM also defined < 50 nmol/L as “insufficient” to maintain bone health, and some scientific reports interpret values below this cut-off as ‘deficient.’ Based on a 50 nmol/L cutoff, the CDC report shows that nearly 90 million Americans (31.7%) have vitamin D deficiency/insufficiency, with higher rates in Non-Hispanic blacks (70.6%) and Mexican-Americans (44.2%).⁷

References

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13 American Academy of Pediatrics Council on Environmental Health, Rogan WJ, Paulson JA, et al. Policy Statement: Iodine deficiency, pollutant chemicals, and the thyroid: new information on an old problem. Pediatrics. 2014 Jun;133(6):1163-6.

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   22   Office of Disease Prevention and Health Promotion. U.S. and Canadian Dietary Reference Intakes (DRI) Committees. Workshop: Options for Consideration of Chronic Disease Endpoints for Dietary Reference Intakes.  Available at: http://health.gov/dietaryguidelines/dri/. Accessed December 23, 2015.