· This is determined by the presence (or absence) of essential amino acids and their distribution. It is “essential” to consume amino acids from food because the body is not capable of manufacturing them. Examples of foods containing protein with all the essential amino acids in a desirable ratio include eggs, cheese, fish, meat, and milk.
· Nonessential amino acids can be manufactured (synthesized) in the body, so it is not “essential” to consume foods that contain them. Most foods contain both nonessential and essential amino acids, however it is the presence of a comprehensive set of essential amino acids that makes a high-quality protein.
· People often take protein supplements, but these might contain proteins with an incomplete set of essential amino acids, making the supplements low in quality and, even if they do deliver a high-quality protein, they tend to be expensive. The best protein supplement would be a few pieces of fish or an egg. Vegetarians can ensure optimal protein quality by combining cereal grains (rice, oats, and wheat) with legumes (dried beans or peas).
· Although protein isn’t the best fuel for physical activity it is a fuel that can help satisfy energy needs if other fuels (i.e., carbohydrates and fat) are insufficient.