In part I of this series, protein was defined, its roles in the body discussed, food sources identified, and the body's requirements explained. In part II of this series, I will review the consequences of too little and too much protein in the diet, as well as discuss vegetarianism.
When the diet is deficient in protein, the body decreases its production of proteins while increasing the use of the body's tissues to supply the amino acids it needs for proper functioning. Over time, this is damaging to the body and leads to impaired growth (in children), impaired brain, kidney, and digestive functioning, as well as a weakened immune system. Obtaining adequate protein on a daily basis is critical for health. Healthy individuals should obtain 10 to 30% of their total daily calories from protein.
As with any nutrient, excessive intake can lead to health issues. That is why moderation is a key concept in nutrition. Excess protein in the diet offers no benefits and could cause harm, especially to those with existing kidney disease. A diet too high in protein increases the workload for the kidneys, thus causing unnecessary strain which can lead to decreased functioning. People with kidney disease are often prescribed a protein-limited diet.
A well-planned vegetarian diet is linked with a reduced risk of heart disease, obesity, and certain cancers. There are many types of vegetarian diets ranging from vegan to lacto-ovo. This is a personal choice; when one is considering omitting or limiting animal-derived foods it is critical to ensure adequacy, balance, and a variety of plant food sources.
Nutrients often lacking in poorly planned vegetarian diets are protein, iron, zinc, calcium, Vitamin D, and Vitamin B12. I've observed vegetarians having a soda and potato chip lunch, vegetarian indeed, but severely lacking in nutrients. Be sure to incorporate whole grains, fortified cereals, fortified almond, rice, and/or soy (organic) milks, seeds, nuts, oils, legumes, fruits, and vegetables (kale, turnip greens, and broccoli supply calcium and iron). Try a new recipe along with a new food every week. The photo shown is of black rice, tofu, and sautéed vegetables. A healthy and satisfying meal that provides a balance of nutrients and was made in less than 30 minutes!
Source: Sizer and Whitney. (2014). Nutrition: Concepts and Controversies, 13th Edition. Wadsworth, Cengage Learning. Photo credit goes to James Davlin.