Chapter 2: Basic Nutrition 23 Animal proteins are complete proteins because they contain all of the different essential amino acids, whereas most plant proteins are incomplete proteins because they are missing or are low in one or more of the essential amino acids. However, not all plant proteins are incomplete as both soybeans and quinoa are complete proteins. Moreover, it is possible to make a complete protein by combining two or more incomplete proteins (e.g., peanut butter on wheat bread) or by combining incomplete plant proteins with small amounts of animal protein (e.g., macaroni and cheese). It is not necessary to combine incomplete proteins at every meal, but rather assess the entire day as a whole to determine if adequate essential amino acids have been provided. Research suggests that protein sources should be spread out throughout the day. This can be achieved by aiming for about a quarter of the plate to be protein at meals (or about the size of your palm) and including a protein source with snacks (Fink & Mikesky, 2021). Frequent consumption of protein is recommended due to the body’s inability to store excess protein as well as the high turnover rate of protein within the body. Fat Similar to carbohydrates and protein, fat also provides several vital functions. In fact, fat is essential for the transport and absorption of the fat-soluble vitamins (i.e., A, D, E and K), the conduction of nerve impulses, the maintenance of cell membranes, and the production of specific hormones. The AMDR for dietary fat is 20-35% of total calories. Fat also provides flavor to foods and contributes to satiety by delaying the time it takes for food to pass through the digestive tract. When fats are added to meals, foods are digested and absorbed more slowly. This is helpful in controlling blood sugar when highcarbohydrate foods are consumed. Fat is the most energy dense of the macronutrients providing 9 calories per gram (as compared to carbohydrates and protein that provide only 4 calories per gram). Due to fat’s high palatability in taste appeal combined with caloric density, eating patterns high in fat (specifically saturated and trans-fat) increase the risk for obesity and other chronic diseases (e.g., hypertension, diabetes, gallbladder disease, breast cancer). Healthy sources of fat can be obtained through a variety of foods such as nuts, nut butters, seeds, avocados, and oily fish (e.g., mackerel, salmon). There are three primary types of fat: monounsaturated fat, polyunsaturated fat, and saturated fat. Both monounsaturated fats and polyunsaturated fats are thought to help lower low-density lipoprotein cholesterol levels (sometimes referred to as “bad cholesterol”) and reduce the risk of heart disease. Sources of monounsaturated fat include nuts, seeds, avocados, olives, olive oil, and canola oil.
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