Micronutrients are nutrients required in smaller quantities than macronutrients (carbohydrates, fats, proteins etc.), including vitamins and minerals.
Without proper levels of micronutrients, our bodies lack the ability to maintain the metabolic processes required to produce energy. It becomes easy to overlook the importance of micronutrients and the role they play in our overall health because they are found in abundance from the many foods we eat every day. However, when athletes or individuals restrict their diets without taking macronutrients into account, they risk becoming deficient in some of these crucial micronutrients.
Whereas macronutrients are the molecules used to produce structure and are metabolized directly for energy, micronutrients (both vitamins and minerals) are critical in maintaining the metabolic processes that produce energy.
A good analogy for this is the different roles that gasoline and oil play when producing energy in a car. Gasoline is the main source of energy (the macronutrients) for the car and it is combusted (oxidized) to generate energy and make the engine run. The oil (micronutrients) is critical for allowing the engine to run smoothly, enabling all the parts to move.
To be more specific, in the context of human nutrition and metabolism, micronutrients are used as coenzymes and cofactors for several of the metabolic reactions and are used quite extensively in the mitochondria to facilitate the electron transport chain.
FAT SOLUBLE VITAMINS
Fat soluble vitamins are defined as those that dissolve in fats and oils.
Due to this ability, fat-soluble vitamins can be stored in the body’s fatty tissue. However, they need to be absorbed along with fats in the diet, meaning that they aren’t easily absorbed without dietary fat being eaten at the same time.
Vitamins A, D, E, and K are the fat-soluble vitamins. Because of their solubility, they are stored in the tissues of the body and play critical roles in metabolism and proper hormonal function.
As dietary fat assists with the absorption of fat-soluble vitamins, it is critical that people consume fat in their diet. Consuming fat-blocking supplements can impair the body’s ability to absorb fat-soluble vitamins. Furthermore, high doses of fat-soluble vitamins consumed over long periods can lead to toxicities as they are stored in tissues rather than excreted when in excess.
WATER SOLUBLE VITAMINS
Water-soluble vitamins are vitamins that can dissolve in water. Due to this ability, they are not stored in the tissues of the body but are present in the blood and other water-based fluids. Many water-soluble vitamins are essential, meaning that they have to be consumed from foods or dietary supplements as opposed to being produced by our bodies. They are found in both animal foods and plant foods.
Excess levels of water-soluble vitamins are excreted. Therefore, urine becomes a vibrant, bright yellow after consuming of a large dose of vitamin B-complex vitamins, vitamin C, or a multivitamin.
Minerals are naturally occurring compounds, often atomic elements, that are needed for life. Similar to vitamins, minerals aren’t made by the body; they need to be included in our diets or be supplemented. However, they are substantially different to vitamins because vitamins are organic while minerals are inorganic. Also, vitamins are often broken down by air, acid, or heat while minerals are not.
Most of the minerals relevant to humans are considered metals. These minerals are critical in bone structure, the antioxidant system, thyroid function, oxygen transport, and a host of other essential processes. Minerals are often overlooked in the diet, especially iodine, chromium, and copper. However, it’s critical that people get adequate mineral nutrition, which can be achieved by consuming mineral-rich foods a few times a week.
Examples of minerals include calcium, chromium, copper, fluoride, iodine, iron, magnesium, phosphorous, potassium, selenium, and sodium.
SO HOW MUCH OF WHAT?
The daily requirement for each micronutrient is explained by several different reference amounts that fall under the umbrella of dietary reference intakes (DRI) as shown below.
Estimated Average Requirement (EAR)
A nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group.
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.
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 can’t be determined.
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.
Although these numbers are carefully determined, it is important to remember that RDA numbers are set on normative population data and that individuals have differing requirements. E.g. athletes versus non athletes. The numbers are to be used as broad guidelines and different populations will 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 ATHLETES NEED MORE?
There hasn’t 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 prevents 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. The evidence suggests that highly active people, (in particular endurance athletes), have an about 70% increased requirement for iron intake when compared to non-endurance athletes (Whiting & Barabash, 2006).
It is worth noting that a lack of systematic investigations into an increased micronutrient demand in athletes doesn’t mean that 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 and the individual athlete in question.
SO WHAT CAN I DO ABOUT IT?
In practice, addressing micronutrient needs can be achieved using pretty simple methods. This is mainly due 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.
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. Yes, a cliché, but this approach to eating provides adequate micronutrition for the water- and fat-soluble vitamins, along with adequate mineral micronutrition.
Supplementation of vitamins and minerals should be viewed as supplements to an otherwise healthy and robust diet – like an insurance policy for a diet that may not meet all of the recommendations. For the most part, much of a person’s micronutrient needs (including athletes) can be met through a diet rich in fruits, vegetables, grains, and some animal products or animal by-products.
Micronutrition can become compromised during periods of overall energy restriction – think of a harsh but also long weight cut or a bodybuilding prep. 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, our bodies are still using a high level of energy and require the same amount of micronutrition.