The Basics of Nutrition

Nutrition is a hot topic. You are likely inundated with nutrition advice regularly whether you want it or not. In this chapter, we will go over the basics of nutrition, but there is so much more that you can learn about the topic. After this chapter, if you are interested in learning more about nutrition, please make sure you are getting your information from reliable sources and from credentialed individuals. While this applies to any advice related to your health and well-being, the author believes it is of particular importance in regard to nutrition. There are many people on social media, as well as those you meet in person, who give nutritional “advice” and “diet recommendations.” However, they may not have the education or background in these areas. When looking for information, it is important that you are getting the information from a reliable source. A dietitian is an expert in the field of nutrition, which is the science of food (Fahey et al., 2020). In this chapter, we will be covering nutrients, both essential and nonessential, macro and micronutrients, and very general recommendations. Specific diets are beyond the scope of this chapter, though some general information and warnings about “fad diets” and also a video link will be provided to yield some “general information” regarding what “diets” are.

Nutrients

Nutrients are defined by Morris and Mohiuddin (2023) as “chemical substances required by the body to sustain basic functions and are optimally obtained by eating a balanced diet” (Morris & Mohiuddin, 2023). There are roughly 50 different nutrients (Kumar et al., 2017 ). These nutrients can be broken down into essential nutrients and nonessential nutrients. The majority of nutrients are essential nutrients. Essential nutrients are nutrients that we need to consume because we cannot make sufficient quantities fast enough or at all on our own (Fahey et al., 2020). Nonessential nutrients are nutrients that the body can make on its own (Kohlmeier, 2015). It is important to note that being able to make a nutrient on our own does not mean that the amount of the nutrient produced will cover an individual’s needs for that nutrient (Kohlmeier, 2015). The terms essential nutrients and nonessential nutrients do not distinguish which nutrients are more important, but rather the nutrients we can make ourselves (nonessential) vs. the ones that we cannot make ourselves (essential). We need to prioritize the consumption of the essential nutrients. This is not to say that it is not ideal to consume nonessential nutrients as oftentimes we do not get to make enough of them. Vitamin D is a nonessential nutrient that people are often deficient in.

Calories

Think about the term “Calorie.” When you hear the term, what do you think about? What immediately comes to mind? Does the term illicit feelings? Does it have a negative or positive connotation for you, or neither?

A kilocalorie can be defined as “ The amount of heat needed to raise the temperature of 1L of water by 1°C” (Kent, 2007). The term “Calorie” that you see on food labels is actually a name for kilocalorie. A kilocalorie is 1,000 calories. The use of “Calorie” is so commonly used in place of kilocalorie, moving forward in this text, we will use the term “Calorie” to denote kilocalorie. Calories are used to measure the energy we get from foodstuffs, as well as the energy we expend. We need calories to live. Everything our body does, from breathing to digesting food to exercising, requires energy, and we get those Calories from things we consume (food/ drinks) in order to provide energy.

Does this change how you view/feel about the term “Calories?”

Calories Provided Per Gram of Nutrient

Carbohydrates: 4 Cal/Grams

Protein: 4 Cal/ Grams

Fat: 9 Cal/ Grams

The US Department of Agriculture and US Department of Health and Human Services (USDA and USDHHS 2020) recommend the following average caloric consumption daily for males and females. Males and females between the ages of 19 and 30 should consume an average of 2,400 and 2,000 Kcal/ per day, respectively. Calorie recommendations decrease slightly with age. Please note that true caloric needs are highly individualized, and the actual ideal intake for each individual depends on other factors, including but not limited to activity level and body size. There are many people that need to consume more calories than those recommended.

Macronutrients

Macronutrients are nutrients that we need to consume in relatively large amounts (Faley et al., 2020). There are four macronutrients, including protein, carbohydrates, fats (also called lipids), and water.

Carbohydrates

The primary function of carbohydrates is to provide energy. Carbohydrates also have a role in the synthesis of nonessential amino acids (Kumar et al., 2017).

When carbohydrates are consumed, they are broken down and converted to glucose (Kenny et al., 2015). This glucose can be found circulating in our blood, being transported to different cells to be utilized for energy, and being stored in the form of glycogen in the muscle and liver. Some cells, such as those found in the brain, nervous system, and in blood, prefer glucose as an energy source (Fahey et al., 2020). Our muscles also utilize glucose as a primary fuel source during exercise.

Primary carbohydrate sources include grains, fruit, and vegetables.

Carbohydrates can be classified as complex or simple. Complex carbohydrates are carbohydrates from starches (grains, potatoes, legumes) and high-fiber carbohydrates (grains, some vegetables, legumes, and some fruits) (Fahey et al., 2020). Simple carbohydrates are single and double sugar molecules. They are found naturally in fruits and milk and added to sweetened desserts, candy, sodas, and sweet beverages such as juices (Fahey et al., 2020).

Complex carbohydrates, specifically complex carbohydrates that are grains, can further be divided into whole-grain carbohydrates or refined carbohydrates. A whole grain is just that, a grain that has all of its original components. These components include the bran, endosperm, and the germ. Whole grains contain fiber, vitamins, and minerals. Examples of whole grains include buckwheat, oats, millet, quinoa, brown and wild rice, amaranth, barley (not pearled), as well as crackers, cereals, breads, and pastas that are labeled as whole grain (USDA and USDHHS 2020). When grains are processed, the bran and germ become removed, and the endosperm is left. Refined grains include white breads, cereals, pastas, and rice. Crackers made from refined grains will not be labeled whole grain (USDA and USDHHS 2020).

The glycemic index is an assessment of how different foods affect blood glucose levels (Esfahani, 2009). As mentioned above, when we consume carbohydrates, they are broken down and converted to glucose. Some carbohydrates are broken down more quickly and cause a fast increase in blood glucose (Fahey et al., 2020). Foods that raise blood glucose levels quickly are considered high glycemic index foods, and foods that offer a slower increase are called low glycemic index foods. Complex carbohydrates (especially those with more fiber) tend to have a lower glycemic index, while simple carbohydrates, as well as starches, have a higher glycemic index.

The USDA and USDHHS (2020) recommend that 45-65% of your total daily calories come from carbohydrates. In some contexts, carbohydrates have been viewed negatively. It is important to remember not all carbohydrates are the same. Hopefully, after reading this section on carbohydrates, you can see how the quality of carbohydrates consumed is important. The large majority of carbohydrates consumed should be from whole grains, vegetables, and fruit, which are high in fiber and micronutrients. Eating whole grains, vegetables, and fruit is drastically different from eating refined carbohydrates and added sugars.

Protein

Proteins also contribute to energy, yielding 4 kcal/ gram consumed but also are key components of the body’s structure. Proteins have structural roles in the blood as components of plasma protein, hemoglobin and coagulation factors (Kumar et al. 2017), and aid in the synthesis of enzymes, cell membranes, and some hormones (Faley et al. 2020). Proteins can also be found in antibodies (Kumar et al. 2017). Proteins make up important structural components of bone and muscle (Faley et al. 2020). Finally, in addition to the above, protein plays a vital role in the balance of both water and ph (acid vs. base) (Kumar et al. 2017). After reading the above, the importance of protein should be obvious. It is imperative for growth and repair (Kumar et al. 2017). When most people think of protein sources, they likely think of animal products, which are a good source of protein, but there are numerous plant sources of protein as well. According to Kumar et al. (2017), all foods contain protein, excluding refined sugar, oil, and fats. With that said, not all protein sources are equal. Proteins are made up of amino acids. There are a total of 20 amino acids, of which nine are considered essential and the other 11 are nonessential.

While plants do provide protein, they are considered incomplete sources of protein. This means that a single plant does not provide all 9 essential amino acids while animal proteins do contain all 9 essential amino acids (Fahey et al. 2020). For a vegetarian, vegan, or someone who gets the majority of their protein from plant sources, it is important to make sure you are getting all your essential amino acids every day. There is one exception to this rule, which is soy. Unlike other plant sources of protein, soy contains all 9 essential amino acids ( Kumar et al. 2017) and thus is a complete protein. The USDA and USDHHS (2020) recommend that 10-35% of your total daily calories come from protein. As with carbohydrates, the source of protein is important. Protein from chicken, fish, tofu, whole grains, and lean meats is superior to highly processed sources like hot dogs, hams, and lunch meats.

Fat

Fats, which are also called lipids, offer energy, specifically during rest and low intensity activities (Fahey et al., 2020). Beyond providing energy, fat is important for insulation, protection, and the absorption of fat-soluble vitamins (see micro nutrients) (Fahey et al., 2020). Dietary fats can be separated into three categories– saturated fats, unsaturated fats, and trans fats.

Saturated fat is found in animal products (such as butter, whole milk, cream and high-fat meats) and is solid at room temperature. There are some plant fats that also contain saturated fats, including coconut oil. The USDA and USDHHS (2022) recommend keeping saturated fat to less than 10% of total daily calories. Once again, the source of saturated fat matters. Saturated fat from quality meat sources is ideal. According to the USDA and USDHHS (2022), the primary sources of saturated fat for individuals in the US include burgers and other sandwiches, tacos and burritos, as well as desserts, sweets, and grain-based dishes such as pastas. Unsaturated fats are plant fats and are typically liquid at room temperature. Unsaturated fats can be broken into monounsaturated fats (olive oil and canola oil) and polyunsaturated fats (corn oil, sunflower oil, and soy oil). The USDA and USDHHS (2022) suggest trading some saturated fats for unsaturated fats, particularly polyunsaturated fats.

Trans fats are created when hydrogen is added to unsaturated fats. The process of adding hydrogen to unsaturated fats is termed hydrogenation. This is done in order to turn a fat that would typically be liquid at room temperature into a solid. The USDA and USDHHS (2020) recommend trans fat consumption be as low as possible. Though some trans fats can be found naturally in animal products, before 2018 the vast majority of trans fats consumed were from partially hydrogenated oils. Due to safety and health concerns, in 2018 the use of partially hydrogenated oils was banned in the US (USDA and USDHHS, 2020).

The USDA and USDHHS (2020) recommend 25% to 35% of daily calorie consumption be from fat, but only 10% from saturated fat and as little as possible trans fats. Research exists linking both saturated fats and trans-fats to increase cardiovascular disease risk.

Water

Water is often overlooked in the discussion of macronutrients. Water doesn’t provide calories, but it is incredibly important. We are able to survive much longer without food (potentially up to 50 days) than without water (a couple of days) (Fahey et al, 2020). Proper hydration is important in order to maintain blood volume, cellular functions, and body temperature. Total water intake comes from water consumed by drinking plain water, water that is found in other beverages, and water that is in the foods we eat (National Academies of Sciences, Engineering, and Medicine, 2005). The Adequate Intake (AI) for water (including other drinks and food containing water) is 3.7 L for young males (19-30 years of age) and 2.7 L for females. Of this amount, 3.0L and 2.2 L for young males and females respectively should come from beverages (not food). That is not to say that some individuals don’t need more. It is imperative that body water intake balances body water loss. A hot, humid environment, as well as exercise, will increase water loss. Water loss that causes a 3% reduction in body weight has been associated with negative impacts on endurance performance in cool environments, while as little as a 2% reduction in body weight has been associated with negative impacts on endurance performance in hot environments (Armstrong, 2000). Dehydration can also negatively impact cognition (Popkin et al., 2010).

Micro Nutrients

Above, an overview of the 4 macronutrients was given. Macronutrients are nutrients we need in large quantities, and micronutrients are nutrients we need in small quantities (a fraction of a mg to multiple grams). There are two groups of micronutrients, vitamins and minerals (Kumar et al. 2017).

Vitamins

 Vitamins play a role in different body processes. Some vitamins aid in chemical processes including metabolism, while others act as antioxidants (aiding in cellular health), assist with red blood cell production, and help maintain nerve, skeletal, and immune functions (Fahey et al., 2020). There are 13 different vitamins (A, C, D, E, K and the eight B vitamins). Some vitamins are fat soluble, while others are water soluble. Water soluble vitamins can be absorbed into the bloodstream, while fat-soluble vitamins are stored in the liver and fatty tissue (Fahey et al., 2020).

Vitamins D and K are our only non-essential vitamins. However, remember that when a nutrient is classified as “non-essential,” it doesn’t mean that it doesn’t need to be consumed to have adequate amounts (Kohlmeier, 2015). Vitamin D deficiency is actually very common (USDA and USDHHS, 2020).

Vitamins are best and most easily absorbed when we consume them from foods we eat (vs. in supplement form). Both vitamin deficiencies and vitamin excess can lead to negative health outcomes. This differs depending on the vitamin one is deficient in or consuming in excess. Use the link below for more resources with specific information about individual vitamins.

Vitamins

Minerals

There are 17 essential minerals, which, like vitamins, all have differing roles. Generally speaking, minerals aid growth, regulating various body functions and assisting in the release of energy (Fahey et al., 2020). Minerals can be separated into two groups, major minerals and trace minerals. Major minerals are minerals that should be consumed in greater quantities (100 + mg/day), and trace minerals are needed in smaller amounts on a daily basis. Major minerals include calcium, phosphorus, magnesium, sodium, chloride, and potassium. Trace minerals include iodine, copper, fluoride, iron, selenium, and zinc (Fahey et al., 2020). As with vitamins, mineral deficiencies and mineral excess can lead to negative health outcomes. Use the link below for more resources with specific information about individual minerals.

Minerals

Deficiency And Excess

 As mentioned above, there are recommendations for all nutrients. Being deficient in a nutrient has consequences, as does over consuming a nutrient. It is important to note whether we are referring to macronutrients or micronutrients. Dietary Reference Intakes (DRI) are reference values related to nutrient intake for healthy people and include recommended dietary allowance (RDA), adequate intake (AI), estimated average requirement (EAR), as well as tolerable upper limit (National Institute of Health Office of Dietary Supplements, n.d.). RDA is the average intake that is enough to meet the nutritional needs of most healthy adults. The designation AI is used when there is not enough information to develop an RDA, and it is what is assumed as adequate or enough to meet the nutritional needs of most adults. EAR is the nutritional intake that is estimated to meet the needs of 50% of healthy people. Finally, UL is the amount of a nutrient one could likely consume before the negative effects of overconsumption could be expected. The National Institute of Health’s “Nutrient Recommendations and Databases” as well as the “Dietary Guidelines for Americans” are linked below if you want more information to learn about specific guidelines for different nutrients.

Nutrient Recommendations and Databases

Dietary Guidelines for Americans 2020 – 2025

Diets

You or someone you know has likely been on a diet at one point or another. Interest in weight loss is becoming increasingly popular. Research by Teng et al. (2020) shows Internet searches about weight loss increased between 2004 and 2018 with a peak in searches in the spring months. While weight loss (specifically fat loss) can be healthy, many individuals are interested in quick fixes that likely are unsustainable. A fad diet can be defined as “a weight loss plan that promises dramatic results over a short-term period” (Gui, 2008). Some characteristics of fad diets include promising fast weight loss, restricting or fully eliminating food groups, use of gimmicks as well as personal anecdotes, and failing to acknowledge physical activity (Gui, 2008). Some popular fad diets include low-carbohydrate diets, ketogenic diets, Paleolithic diets, low-fat diets, vegan and vegetarian diets, intermittent fasting (Anderson, 2023), and detox diets (Tahreem et al. 2022).

If you, or someone you know, has tried what would be considered a “Fad Diet,” What happened? Was weight loss achieved? Were they able to maintain the diet? Were they able to maintain the weight loss?

This is not to say that weight loss is never a good idea. Weight loss, when needed, can be achieved but should be done so with sustainable changes that do not restrict any food groups. For example, Gui (2008) suggests monitoring calorie consumption, consuming moderate amounts of primarily complex carbohydrates (fruits, vegetables, and whole grains), protein, and fat, and utilizing foods with low caloric density to satisfy the need for larger portions without the added calories, and consuming foods that taste good and fit your lifestyle.

The author of this text strongly believes that food should be enjoyed, and we should allow space for all foods (that we can safely consume and enjoy) in our daily diet.

The following video sheds more light on what “healthy eating” is.