CHAPTER 10 Micronutrients LESSON 4 Micronutrient Application
Based on a 2,000 kcal per day diet following USDA guidelines for meeting micronutrient needs, match the recommended daily quantities with their appropriate food category. To begin, click an item in the left column. Then, click the matching answer in the column on the right.
4 servings - Fruit 3 cups - Dairy (milk, cheese, or yogurt) 3 oz - Whole grains 5.5 oz - Meats, Poultry, or Fish 2.5 cups - Vegetables
Estimated Average Requirement (EAR)
A nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group.
Adequate Intake (AI)
A value based on observed or experimentally determined approximations of nutrient intake by a group (or groups) of healthy people - used when an RDA cannot be determined.
Macro- and Micronutrient Breakdown
Example: 2,000 kcal per day diet following USDA guidelines for meeting micronutrient needs
Daily Reference Intakes in the General Population Research collated over the past several decades has illuminated RDAs for the major micronutrients present in the human diet for the general population. See Handout: Micronutrient RDA for a complete list of RDAs for the vitamins and minerals discussed and to help support your discussions with clients ("Office of Dietary Supplements - Nutrient Recommendations: Dietary Reference Intakes (DRI)," n.d.).
It is important to remember that RDA numbers are set on normative population data and that individuals have differing requirements. These are to be used as broad guidelines and some populations may have different requirements. For example, people who are located in higher latitudes require more vitamin D from their diet than people who live closer to the equator. Do female athletes, on average, require more iron relative to their calorie intake than males? Each client is unique and has their own unique needs; however, making individual recommendations is tricky and should be done by a registered dietitian nutritionist.
People Restricting Energy & Other Populations of Concern for Deficiencies
Micronutrition often becomes compromised during periods of overall energy restriction, or in diets that restrict specific food groups or have very strict rules surrounding food choices. Long periods of caloric restriction or substantial weight loss also place people at risk for developing micronutrient deficiencies. Long periods of overall caloric restriction typically lead to less micronutrition as less overall food is being consumed. Despite the decreased intake in micronutrients from less food, the body is still using a high level of energy and requires the same amount of micronutrition. In one study, participants who were obese with suboptimal levels of micronutrition saw further decreases in micronutrient status during a 3-month period of caloric restriction and weight loss (Damms-Machado, Weser, & Bischoff, 2013). This decrease occurred despite consuming a protein-rich formula diet containing vitamins and minerals that were designed to cover the DRI.
Supplementation
Supplementation of vitamins and minerals should be viewed as supplements to an otherwise healthy and/or robust diet. For the most part, much of a person's micronutrient needs (including athletes) can be met through a diet that is rich in fruits, vegetables, grains, and some animal products or animal by-products. Thus, even in societies where dietary quality may appear to be poor or with a chronic disease driven by excess consumption, these dietary patterns do appear to largely meet micronutrient levels in a robust manner. Critical! This type of dietary pattern is achieved quite readily by developed countries (including the United States) with deficiencies in micronutrients ranging from less than 1% for folate, vitamin E, and vitamin A, to about 10% for vitamin B6 (Centers for Disease Control and Prevention, 2014). A recent study examining the behavior patterns of individuals who take supplements compared to those who do not found that, on average, individuals who do take supplements tend to have a 1 kg/m2 lower BMI and an overall healthier diet than people who do not consume supplements (Anders & Schroeter, 2017). This data seems to suggest that, for most people who consume supplements, dietary supplements are likely to be function of nutrient support and not as placeholders for an otherwise nutrient-dense diet. While the general population should rely primarily on food sources for micronutrients, there are some populations in which supplementation ought to be considered in addition to a food-based diet as a standard approach. For example: Aging and/or institutionalized populations benefit from vitamin D and/or calcium supplementation (Krieg et al., 1999; Meehan, 2014). Individuals with celiac disease benefit from additional folate, vitamin B12, vitamin D, and calcium supplementation (Caruso, Pallone, Stasi, Romeo, & Monteleone, 2013), and pediatric patients with intractable epilepsy benefit when placed on a ketogenic diet (Lee, Kang, & Kim, 2016). Again though, it is an important reminder that any diet or supplementation recommendation legally needs to come from a RDN.
Recommended Dietary Allowance (RDA)
The average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98%) healthy individuals in a group.
Table: Reference Intake Descriptions
The daily requirement for each micronutrient is explained by several different reference amounts that fall under the umbrella of dietary reference intakes (DRI) There is a systematic process for how each of these reference values are defined. The EAR is determined through a systematic review of the literature and uses human data and animal data to help determine an accurate EAR. The RDA is then calculated by using either two standard deviations or coefficient of variation for the EAR of 10%, which is ordinarily assumed. The AI is set when there is not enough evidence in the scientific literature to establish an EAR and is often limited to specific groups of people in which there is evidence.
Bioavailability
The extent to which an ingredient, food, or other substance is absorbed by the body. For example, the bioavailability of fat-soluble vitamins is greatly impacted by what they are consumed with. When consumed with dietary fat, their bioavailability is much higher than when consumed without fat. Conversely, the bioavailability of iron is impacted by the form of iron consumed. However, there are some factors that tend to make some micronutrients more or less bioavailable: the food source, co-ingestion with other foods/molecules, and what form the micronutrient is in or is bound to.
Tolerable Upper Intake Level (UL)
The highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population - as intake increases above the UL, the risk of adverse effects increases.
Micronutrient Programming
The vast range of micronutrients, their roles in the human body, and the varying levels of requirements can make dietary recommendations for meeting micronutrient needs appear complex and daunting. However, in practice, addressing micronutrient needs can be achieved using simple approaches. This is due, in large part, to the body's regulatory mechanisms for helping clear excess nutrients, regulating absorption, and having wide ranges between meeting daily minimum requirements and upper limits of intake. Furthermore, micronutrients are present in most of the available and commonly consumed foods. This section will discuss how to apply the knowledge learned in this module to your clients and supporting their nutritional needs.
The Effect of Physical Activity on Daily Recommended Intakes
There are additional considerations when determining DRIs for people who undertake higher levels of physical activity: increased energy demands, larger muscle mass, increased loss of solutes due to excessive sweating, and so on. It seems clear that athletes are likely to have different daily requirements for micronutrients than non-athletic populations; however, there are some substantial limitations that prevent the development of guidelines for athletes. Namely, small sample sizes, vastly different energy requirements and micronutrient utilization, different perspiration rates and overall volume of fluid and micronutrients loss due to perspiration, and so on. As such, there is currently not enough literature basis to establish separate and individual DRIs (EAR, RDA, AI, and UL) for athletic populations. There has not been a systematic evaluation of the literature that examines the effect of physical activity on micronutrient needs. Most evidence is in the form of examining higher-dose supplementation in micronutrient deficient athletes, which precludes us from drawing conclusions about setting distinct DRI values for highly active people; however, there is some data available that can help guide some decisions. One of the most studied micronutrients impacted by physical activity is iron. In this example, the evidence suggests that highly active people, especially long-distance runners, have an about 70% increased requirement for iron intake when compared to non-runners (Whiting & Barabash, 2006). Use Handout: Effects of Physical Activity on Micronutrient DRI to help support the discussions you have with your clients. Food For Thought A lack of systematic investigations into an increased micronutrient demand in athletes does not mean the problem is nonexistent. More research is required on this topic. Individualized nutrition is a critical part to successful dietary management in athletes, part of which requires understanding micronutrient status.
Multivitamin/Mineral vs. Individual Nutrients
There are both advantages and disadvantages to taking individual nutrients as a supplement when compared to a multivitamin. Using single nutrients can impart the ability to target and correct single nutrient deficiencies quicker and more effectively. For example, an individual can correct a vitamin D deficiency much faster supplementing with higher doses of vitamin D (e.g., 1000 IU per day) than if they were consuming vitamin D at lower doses (e.g., 100 IU per day) as part of a multivitamin. Controlling the exact type, source, and dosage, is easier when using individual nutrient supplements. If someone needed to supplement with a heme-based iron at a specific dosage based on their doctor's recommendation, then using a single nutrient supplement would be more effective. However, there are some advantages to using multivitamins. Micronutrients often work synergistically and the doses found in multivitamins make it more difficult to develop micronutrient toxicities, especially from fat-soluble vitamins. Both individual nutrient supplements and multivitamins can be used to supplement a diet. Each approach has benefits, with neither being inherently better or worse than the other. They should be viewed as tools that are recommended by a qualified healthcare practitioner.
Deficiencies with Celiac Disease
There is also some concern for nutrient deficiencies among people with celiac disease. Those with celiac disease must restrict gluten-containing foods in their diet. Further, because of the nature of the disease, which affects digestion and absorption in the intestine, it can also have a negative effect on nutrient transport and absorption. In a study of newly diagnosed people with celiac disease, 87% of people had at least one nutrient that was considered deficient; 7.5% were deficient in vitamin A, 20% in vitamin B12, 67% in zinc, and roughly 46% showed decreased iron storage
Covering the Food Spectrum
There is no singular diet or approach to eating required to achieve complete macro- and micronutrition. The human diet has evolved over millennia, continents, and myriad cultural and technological revolutions, resulting in a breadth of different dietary approaches, many of which meet modern-day nutrition guidelines. As stated by the Food and Agricultural Organization of the United Nations (2002), Advice for a healthy diet should provide both a quantitative and qualitative description of the diet for it to be understood by individuals, who should be given information on both size and number of servings per day. The quantitative aspects include the estimation of the amount of nutrients in foods and their bio-availability in the form they are actually consumed. The qualitative aspects relate to the biologic utilization of nutrients in the food as consumed by humans and explore the potential for interaction among nutrients. Pragmatically speaking, achieving complete macro- and micronutrition in the developed world is best achieved by eating a well-balanced diet: several servings of fruits and vegetables, whole grains, and lean meats or fish (Table: Micronutrient Sufficient Diet Example).
Table: Micronutrient Sufficient Diet Example
This approach to eating provides adequate micronutrition for the water- and fat-soluble vitamins, along with adequate mineral micronutrition. An example of the macro- and micronutrient breakdown of this dietary pattern can be seen below. In order to easily achieve complete micronutrition, it is best to avoid diets that utilize severe restriction of macronutrients (e.g., very-low-carb diets), omit entire food groups (e.g., vegan diets or the keto diet), or eat very-low energy for extended periods of time. Further, these specific protocols, or any others, should be discussed with a RDN and supported by a Nutrition Coach. While there are special considerations for unique populations, the moderate, balanced approach achieves complete macro- and micronutrition for greater than 90% of the population.
Match the reference intake label acronym with its respective description. To begin, click an item in the left column. Then, click the matching answer in the column on the right. ERA RDA AI UL
UL - The highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population. AI - A value based on observed or experimentally determined approximations of nutrient intake by a group (or groups) of healthy people—used when an RDA cannot be determined. ERA - A nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group. RDA - The average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a group.
