How much protein do you need
June 01, 2013
by Gabe Mirkin, MD
Protein supplies the building blocks for all the tissues and functions in
your body. These building blocks, amino acids, are used to make new cells
and all the enzymes and other chemicals your body requires to function.
Your body uses 22 different amino acids, and nine of those must come from
the food you eat. These are called the essential amino acids. Your body
can make the remaining amino acids it needs from the essential nine.
The Recommended Daily Allowance (RDA) for protein is about 50 to 70 grams
per day. Most foods contain protein, and it is easy to meet your protein
requirements with a typical varied diet. For example, you would meet your
daily requirement for protein if you ate two of cups each of beans and
whole grains such as barley, brown rice or oatmeal, three ounces of tuna,
and two glasses of milk or a vegetarian milk substitute. If you are not
sure whether you eat enough protein, keep track by checking the labels of
the foods you eat for a few days. You will probably find that you are
getting plenty of protein without any special effort.
Protein deficiency is virtually unheard of in North America, since any
reasonably varied diet will give you enough. Before you decide to follow
a high-protein diet or take protein supplements, understand that your
body cannot store excess protein. Your stomach acids and enzymes in the
stomach and intestines break down proteins into amino acids which pass
from the intestine into the bloodstream. If your body needs to build
protein, your liver combines amino acids to form body proteins. Any
unused protein is burned for energy or stored as fat, and this process
can stress the kidneys or liver and may pull calcium out of bones.
Most plants contain some but not all of the essential amino acids.
Vegetarians can get all the amino acids they need from whole grains and
beans. The beans may contain only seven of the essential nine, but the
grains will have the other two. You do not need to do special
combinations at each meal to get “complete protein”; just eat a variety
of whole grains, beans, seeds and vegetables in your regular diet.
If you are an athlete or a heavy exerciser, read my report on Muscles and