Protein is needed to rebuild body tissues such as muscles and organs.

Muscles are built from protein. Unlike fat cells for fat and muscle or liver for glucose, there is no place in the body to store protein. We need to consume enough protein to allow our muscles to be healthy and perform work.

Animal and plant or vegetable foods are the two major protein sources. Animal protein foods include meat, poultry, fish, dairy products and eggs and are said to be of high biological value. That is, they contain all nine essential amino acids that can not be synthesized in the body (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine).

Plant protein sources, although good for certain essential amino acids, do not always offer all nine essential amino acids in a single given food. For example, legumes lack methionine, while grains lack lysine. What is needed are complementary proteins, various protein food sources that, eaten together, enable a person to meet the standards of a high biologic protein diet.

If vegans eat a variety of plant foods -- cereals, nuts, seeds, grains and legumes -- they'll be fine. They don't have to eat all these food items at a given meal. However, they should consume most or all of them during the course of the day to insure a well-balanced protein diet of high biological value.

The typical American diet is already providing plenty of protein.

When people start consuming too much protein (over 2.0 g/kg/d), the extra protein can become a stressful stimulus for the kidney. This is even more of a concern as we get older and our organs are less efficient and effective.

Very high levels of dietary protein have also been correlated with increased urinary calcium excretion. The loss of calcium through urine could potentially be harmful for bone turnover, with the added risk of osteoporosis. Finally, protein requires vitamin B6 in order to be metabolized and ultimately utilized in the body. Very high levels of dietary protein increase the requirement for this B vitamin.

There are many high protein/high fat/extremely low carb diets currently being promoted for weight loss and diabetic glucose control. Mainstream medical opinion is these diets put diabetics at greater risk for kidney damage.

A search engine search will render many results similar to the following.

Below you will find statements from a few of many different sources expressing current thought on proteins in the diet. You may access the full article by clicking on the links provided.

Why is a low protein diet necessary?

Protein is needed for growth, upkeep and repair of all parts of your body. Protein comes from the food you eat. When your body digests it, a waste product called urea is produced. If the kidneys are not working well, urea can build up in the bloodstream and may cause loss of appetite and fatigue. Eating a low-protein diet will reduce the workload on the kidneys so that the remaining healthy part of the kidney does not have to work so hard. There are two main sources of protein:

http://www.kidney.org/atoz/atozItem.cfm?id=89

National kidney foundation

People with reduced kidney function need to be aware that some parts of a normal diet may speed their kidney failure.

Protein.

Cholesterol.

By restricting carbohydrates drastically to a mere fraction of that found in the typical American diet, the body goes into a different metabolic state called ketosis, whereby it burns its own fat for fuel. Normally the body burns carbohydrates for fuel -- this is the main source of fuel for your brain, heart and many other organs. A person in ketosis is getting energy from ketones, little carbon fragments that are the fuel created by the breakdown of fat stores. When the body is in ketosis, you tend to feel less hungry, and thus you're likely to eat less than you might otherwise. However, ketosis can also cause health problems, such as kidney failure…………………..

What Are the Health Risks Associated With High Protein, Low Carb Diets?

High protein diets can cause a number of health problems, including:

Kidney failure.

High cholesterol.

Osteoporosis and kidney stones.

Cancer.

Unhealthy metabolic state (ketosis).

http://www.webmd.com/content/article/46/2731_1666

WebMD Medical Reference in collaboration with The Cleveland Clinic

Protein cannot be stored and needs to be replenished daily. Muscle wasting can occur if protein intake is inadequate as it may be needed for more important body functions. However, most people eat more than they need in terms of protein. The train of though that strength athletes followed is that the more material you supply the body the more it will build. That is not true. The body will only use the precise amount of protein it needs. The rest will be excreted in the urine and excess amount may even cause liver and kidney strain. It can also cause an increase in calcium loss in the urine as well as dehydration.

http://healthfitness.com.au/diet/nutrition/protein-proteins.htm

Question

When I enter 35% for my protein intake in your Healthy Body Calculator, I get an error message that 35% is too high. I am a weightlifter and this is not 'unreasonable'. Please fix this or find a way to enter whatever values we would like. I like your page and would like to keep using it.

Answer

Actually, protein intakes above 20% are not recommended based on current research, even for weight lifters. High protein intakes stress your kidneys and do not result in greater muscle gain.

http://www.dietitian.com/protein.html

high protein to repair kidney

Protein.

http://kidney.niddk.nih.gov/kudiseases/pubs/hemodialysis/

National Institute of health