12.3 Micro Nutrients
This section will explore the essential micronutrients that play a vital role in overall health and well-being. Micronutrients, consisting of vitamins and minerals, are required in small quantities but significantly impact the body’s physiological functions. While (as their name implies) micronutrients are only needed in very small amounts, they provide the foundation for many metabolic and physiological processes in the body. Vitamins and minerals have specific jobs when one (or more) of these micronutrients is in limited supply, deficiency symptoms emerge, which can then give us clues about dietary needs and quality.
As a personal trainer, understanding the importance of these micronutrients will enable you to provide comprehensive guidance to your clients, promoting optimal health and performance. In this section, you will learn the various roles micronutrients play in the body, how to recognize the symptoms accompanying micronutrient deficiency, and strategies to correct such deficiencies. You will also learn to be aware of and recognize micronutrient toxicity, which is imperative given the popularity of dietary supplements.
With the knowledge acquired in this chapter, you will be better equipped to help your clients make informed decisions about their diet and nutritional needs. In addition, by ensuring that your clients receive the right balance of micronutrients, you will promote optimal health, wellness, and physical performance while minimizing the risk of deficiencies and potential health issues.
12.3.1. Vitamins
Vitamins are organic compounds, which means they contain carbon and are needed in trace amounts in the body (Gropper et al., 2021). Despite requiring only small amounts, vitamins are crucial for several essential regulatory functions, including growth, digestion, energy transfer, and nervous system function. One of the most critical roles of vitamins is as co-factors for enzymes. For instance, vitamin B3 (niacin) is a co-enzyme that forms NAD (nicotinamide adenine dinucleotide), an electron transporter significant in energy transfer. While vitamins are essential in the diet (i.e., they generally are not synthesized in appreciable amounts by the human body) and intimately involved in the body’s energy transfer processes, they do not act as direct or fuel sources.
Vitamins can be defined using the following criteria:
* Vitamins are natural components of foods, usually present in very small amounts
* Vitamins are essential for normal physiological functions (e.g., growth, reproduction, etc.)
* Vitamins, when absent from the diet, will cause a specific deficiency
Vitamins are generally categorized as fat-soluble or water-soluble, depending on whether they dissolve well in lipids (fat) or water. Vitamins A, D, E, and K are classified as fat-soluble vitamins. Fat-soluble vitamins are mostly absorbed passively in the gastrointestinal tract and usually must be transported bound to dietary fat. In the body, fat-soluble vitamins are typically found in the portion of the cell containing fat, such as cell membranes and lipid droplets. These vitamins are mainly excreted through our feces.
The B vitamins and vitamin C are water-soluble. These vitamins are absorbed by both passive and active mechanisms in the gastrointestinal tract and rely on carrier proteins for transport. Since body water is always being turned over, water-soluble vitamins are not stored in large amounts in the body; they are typically excreted in the urine along with their breakdown products.
There is no one-size-fits-all approach to meeting vitamin needs. Many factors can influence our vitamin requirements, such as gender, malabsorption syndromes, prescription medications, stress, exercise, and age-related changes. For example, menstruating women should include plenty of iron in their diet. However, additional iron may be dangerous for men, causing hemochromatosis and organ damage. In addition, people suffering from malabsorption syndromes (e.g., Crohn’s disease, ulcerative colitis, celiac disease, cystic fibrosis, pancreatitis, etc.) may be deficient in multiple vitamins. These individuals should be tested for vitamin and mineral deficiencies, and a vitamin and mineral management strategy should be adopted if required. Assessing vitamin status is likely a good strategy for most adults, whether suffering from malabsorption or simply a poorly diet.
Here is a list of vitamins that are most commonly used for successful physical performance:
* Vitamin A: Helps maintain skin and mucous membranes and contributes to night vision. Excess vitamin A intake can be toxic, as it is fat-soluble. Vitamin A can be found in carrots and yellow vegetables.
* Vitamin B1 (Thiamin): Responsible for carbohydrate metabolism and nervous system function. Because it is water-soluble, daily replacement is necessary. Whole grains are the best source of B1.
* Vitamin B2 (Riboflavin): Involved in energy production and cell maintenance. Eggs are excellent sources of vitamin B2.
* Vitamin B3 (Niacin): Has numerous responsibilities in various bodily functions and is present in every cell in the body. Peanuts and poultry are good sources of B3.
* Vitamin B5 (Pantothenic Acid): Essential in forming the chemical acetylcholine, involved in nerve transmission and memory, and crucial in energy metabolism. Poultry, fish, and whole grains provide ample levels of this vitamin.
* Vitamin B6 (Pyridoxine): Involved in sugar, fat, and protein metabolism. It can be found in wheat germ, fish, and walnuts.
* Vitamin B12 (Cobalamin): Important in the metabolism of protein and fat and aids in red blood cell production. Sources include liver, oysters, and clams.
* Folic Acid (Folate): A B complex group helper substance, especially in red blood cell formation. Five milligrams a day is recommended for athletes.
* Biotin: Helps metabolize carbohydrates and fats. The best sources are brown rice and soybeans.
* Choline: Crucial in normal brain function (notably memory) and acts as a factor in metabolizing fat and cholesterol. The best food sources are eggs and lecithin.
* Inositol: Plays an important role in the transmission of nerve impulses. Lecithin and wheat germ are good sources of inositol.
* PABA (Para-aminobenzoic acid): Essential for normal skin and hair growth. Sources include whole grains and wheat germ.
* Vitamin C (Ascorbic Acid): A water-soluble vitamin involved in various bodily functions. Citrus fruits provide a good source of vitamin C.
* Bioflavonoids: Contribute to the strength of capillaries and help protect vitamin C stores in the body. These compounds can be found in fresh raw vegetables and fruits.
* Vitamin D (Calciferol): A fat-soluble vitamin that regulates calcium and phosphate metabolism. Sunlight is the best vitamin D source, but it is also added to milk.
* Vitamin E (d-alpha-tocopherol succinate): A fat-soluble vitamin with numerous responsibilities in the body. Important for fighting free radical damage inside the body. Food sources include wheat germ, green leafy vegetables, whole grains, and vegetable oils.
12.3.2. Minerals
Minerals, like vitamins, are also required in small amounts by the body. Although they do not serve as direct energy sources, they are essential and must be obtained from the diet.
Dietary minerals can be categorized into macrominerals (required in amounts of 100 mg/day or more) and trace minerals (required in amounts less than 100 mg/day). Collectively, macrominerals and trace minerals often serve as building blocks for body structures, forming the foundation of teeth and bones and helping to construct other cells and enzymes.
Minerals can act as co-factors in enzymatic reactions or function as enzymes. Furthermore, minerals can act as electrolytes that maintain the electrochemical gradient across the cells of our bodies. Electrolytes are critical for regulating muscle contractions, establishing fluid balance, and generating nerve impulses.
Our bodies and the foods we eat contain an abundance of minerals, which we absorb in an electrically charged state (or an “ionic state”): either the minerals are missing an electron (positive charge) or have additional electrons surrounding them (negative charge). In the diet, this charged state allows the minerals to bond readily with water, facilitating absorption. In the body, this charged state helps create concentration gradients across cell membranes, enabling the electrolytes’ functions.
Other molecules found in food, such as phytates, oxalates, and acids, can affect our ability to absorb minerals. For example, phytates in tea and coffee can inhibit iron absorption. Therefore, a person taking an iron supplement is usually instructed to avoid taking it with those beverages. Conversely, the acidity of vitamin C can reduce iron from ferric (3+) to ferrous (2+) form, which is ideal for crossing the gut barrier and enhancing absorption.
Obtaining most of our micronutrients from food rather than dietary supplements is generally recommended. This is because food sources contain complex varieties of nutrients that may act synergistically to promote good health. Indeed, some research has shown that vitamins and minerals delivered via whole food sources provide more significant health benefits when compared to those delivered in supplement form. A few large-scale trials, such as studies of vitamin E, were even halted when researchers found that supplementation had the opposite effect than observed with food sources – when consumed in isolation, the supplements appeared to increase, rather than decrease, disease risk. In addition, many whole foods also contain non-vitamin and non-mineral chemicals called phytochemicals, which have been shown to play a role in human nutrition.
Below are some of the minerals essential for physical performance:
* Calcium: The most abundant mineral in your body, calcium contributes to the composition of your teeth and bones and is required for muscle contractions. Only about 10% of the calcium in dairy products is absorbed in your body. Many people are deficient in this mineral due to this low absorption rate. Athletes deficient in calcium may experience stress fractures. Good sources of calcium include dairy products and calcium carbonate supplements.
* Magnesium is essential for muscle contractions, particularly in the relaxation phase. A lack of magnesium can cause fatigue, spasms, muscle twitching, and muscle weakness. Foods rich in magnesium include soybeans, leafy vegetables, brown rice, whole wheat, and apples.
* Phosphorus: As the second most abundant mineral in your body, phosphorus is involved in muscle contractions and helps utilize foodstuffs. Consuming large quantities of phosphorus might deplete calcium and magnesium in your bones, muscles, and organs, leading to weakness. Quality sources of phosphorus include fish and poultry.
* Iron: Iron is crucial for producing hemoglobin in your blood and transporting oxygen during endurance activities. An intake of more than 50 milligrams per day for prolonged periods can be toxic. Coffee and tea consumption can limit the absorption of iron. The best source of iron is meat, and even cooking in an iron skillet can increase the iron content in your food.
* Copper: Copper helps convert iron to hemoglobin and promotes the use of vitamin C. Most foods contain copper.
* Zinc: Zinc is responsible for cell growth by acting as an agent in protein synthesis. It also aids in the utilization of vitamin A and B-complex vitamins. Zinc can prolong muscle contractions, increasing your endurance. Sources of zinc include eggs, whole grains, and oysters.
* Manganese: Manganese is essential for numerous functions, including glandular secretions, protein metabolism, and brain function. Excessive manganese can inhibit the absorption of iron. Manganese food sources include tea, leafy green vegetables, and whole grains.
* Sodium and Potassium: These minerals must be balanced for optimal muscular power. Sodium and potassium are required for the transmission of nerve impulses. Deficiencies can result in cramping and weakness. Good sources of these minerals include green leafy vegetables, bananas, citrus, and dried fruits. Note that salt tablets for sodium intake are not recommended.
12.3.3. Phytochemicals
Phytochemicals are non-nutritive plant chemicals that provide various health benefits. Though over a thousand phytochemicals exist in our food supply, only a few have been isolated in labs. Examples include resveratrol, isoflavones, lycopene, lutein, and naringenin in grapes, soy, tomatoes, spinach, and grapefruit. Some phytochemicals can influence our response to drugs, like naringenin, which inhibits the liver’s cytochrome P450 enzyme system, affecting statin medications.
These chemicals can help prevent diseases through various mechanisms, including functioning as antioxidants, influencing hormonal function, protecting DNA from carcinogens, and exhibiting antibacterial and antiviral properties. However, modern diets often lack sufficient whole foods, leading to nutrient deficiencies and health issues. That is why it is recommended that most adults take a daily multivitamin/multimineral supplement to help address this issue (Fletcher & Fairfield, 2002).
12.3.4. Water
Water plays a crucial role in various biochemical reactions within the body, serving as an essential component for numerous processes. For instance, water is necessary for splitting molecules, storing carbohydrates, facilitating critical processes such as glucose transportation, waste elimination through blood, urine, and sweat, and dissipating heat through the skin. Adequate water intake is vital for maintaining optimal performance and preventing dehydration-related health risks. Severe dehydration in athletes can lead to medical emergencies such as heat stroke, kidney failure, and seizures.
Athletes should drink water before, during, and after exercise to minimize dehydration. Additionally, they should adapt their water intake based on exercise intensity, duration, and environmental conditions. Thirst is not always an accurate indicator of hydration levels, as one may only feel thirsty once already dehydrated. Monitoring urine color and volume is a more reliable gauge of hydration status. Clear urine with a reasonable volume indicates proper hydration, while dark and scanty urine suggests inadequate water intake.
According to recommendations, men should aim for a daily fluid intake of 3,000 ml, while women should aim for 2,200 ml. Consuming additional fluids during exercise or in hot weather is important, especially when trying to prevent recurrent kidney stones (Meinders, 2010). Another guideline suggests that for every 1,000 calories burned daily, it is advisable to consume one quart of water (Clark, 2019). As a general rule, we recommend drinking enough water to keep your urine clear. The color of urine can vary depending on an individual’s hydration level. When a person is adequately hydrated, their urine tends to be a pale yellow or straw color. This color is generally considered an indication of normal hydration. On the other hand, if urine appears darker, such as a deep yellow or amber color, it can suggest dehydration. The change in urine color is the concentration of waste products and the amount of water in the body. When someone is dehydrated, their kidneys conserve water, resulting in more concentrated urine with a higher concentration of waste products. As a result, this concentrated urine can appear darker in color.
Overhydration can result in hyponatremia or low sodium levels, presenting symptoms similar to heat exhaustion, such as nausea, headache, confusion, and muscle cramps. If increased water intake worsens an individual’s condition in hot environments, it may indicate hyponatremia rather than heat exhaustion. To maintain proper hydration, it is essential to balance water intake with the body’s needs, avoid excessive consumption, and ensure adequate electrolyte balance. Consuming sports drinks containing electrolytes or incorporating electrolyte-rich foods in the diet can help maintain electrolyte balance during prolonged physical activity or in hot environments.
Dehydration occurs when the body loses water and experiences an imbalance in electrolyte levels, specifically sodium, and potassium.
Even mild dehydration prompts the body to conserve water by reducing its elimination. Fluid restriction, in turn, causes the body to retain more water.
To address dehydration, it is essential to replenish the body’s water supply and restore normal electrolyte levels. Dehydration can result from insufficient water intake, excessive water loss, or simply failing to drink enough fluids. By the time thirst is felt, dehydration has already set in.
On average, an individual loses around 2.5% of total body water daily. Therefore, engaging in activities beyond normal routines, such as exercise, sports, or yard work, increases the risk of dehydration.
Activities that cause perspiration reduce body fluid levels, with strenuous activities having a more significant impact and potentially leading to rapid dehydration. The American College of Sports Medicine (ACSM) recommends consuming 7-10 ounces of water every 10-20 minutes during exercise, depending on individual sweat rates, and adjusting the volume accordingly. Furthermore, the ACSM suggests that water is sufficient for exercise lasting less than one hour to maintain hydration. However, consuming a sports drink containing electrolytes and carbohydrates may be beneficial for exercise exceeding one hour. After exercise, consuming 20-24 ounces of water for every pound of weight lost is recommended to rehydrate effectively. It is essential to monitor individual needs and adjust fluid intake accordingly, as sweat rates and fluid requirements vary among individuals.
Water is undeniably crucial, particularly for those who are physically active. As the primary component of the human body, adequate water intake is vital for optimal athletic performance. While other beverages like milk, sugary soft drinks, and fruit juices can quench thirst, they may increase the body’s need for water.
