The USDA recommends 56 grams of protein a day for a man age 40 weighing 160 lb, and 46 grams of protein for women - based on a 40 yr old woman who weighs 140 lb. That’s about 0.36 grams of protein for every pound of body weight. But protein needs vary depending on age, size, growth, health, physical activity, body type, pregnancy and lactation.
Protein & Essential Amino Acids
Protein is essential for health, along with carbohydrates and fats. We use protein to make building blocks, called amino acids, for every part of our bodies: blood, skin, cartilage, muscles and bones, hormones and enzymes.
Our bodies can synthesize 16 of the 23 amino acids that we need. That leaves 8 essential amino acids (9 for children), which must come from the foods we eat.
The Essential Amino Acids Have Important Functions In The Body:
- Isoleucine (Ile) - for muscle production, maintenance and recovery after workout. Involved in hemoglobin formation, blood sugar levels, blood clot formation and energy.
- Leucine (Leu) - growth hormone production, tissue production and repair, prevents muscle wasting, used in treating conditions such as Parkinson’s disease.
- Lysine (Lys) - calcium absorption, bone development, nitrogen maintenance, tissue repair, hormone production, antibody production.
- Methionine (Met) - fat emulsification, digestion, antioxidant (cancer prevention), arterial plaque prevention (heart health), and heavy metal removal.
- Phenylalanine (Phe) - tyrosine synthesis and the neurochemicals dopamine and norepinephrine. Supports learning and memory, brain processes and mood elevation.
- Threonine (Thr) monitors bodily proteins for maintaining or recycling processes.
- Tryptophan (Trp) - niacin production, serotonin production, pain management, sleep and mood regulation.
- Valine (Val) helps muscle production, recovery, energy, endurance; balances nitrogen levels; used in treatment of alcohol related brain damage.
- Histidine (His) - the 'growth amino' essential for young children. Lack of histidine is associated with impaired speech and growth. Abundant in spirulina, seaweed, sesame, soy, rice and legumes.
Complete and Incomplete Protein:
ALL plant based foods have varying amounts of protein (plus carbohydrates, fats and other good things), and the body will combine proteins from all sources, to make 'complete protein'. That's true for everybody, veg or non-veg.
The term 'complete protein' means that all eight essential amino acids are present in the correct proportion.
Foods from animal sources have complete proteins Some foods from the plant kingdom, such as soy and quinoa, have complete protein.
The term 'incomplete protein' refers to foods which have all the essential amino acids, but are low in one or more of them. That's called the 'limiting amino acid'.
Most plant foods have one or more limiting amino acids which limit the availability of all the other amino acids in the food. That's why these foods are called 'incomplete proteins'.
For example, the limiting amino acid in grains is usually lysine (Lys); in legumes it can be methionine (Met) and tryptophan (Trp). So, the low level of Lys in grains is complemented by a higher level in legumes, and vice versa, to make 'complete protein'.
However, vegetarians and vegans don't need to worry about complete and incomplete protein. It is NOT NECESSARY for vegetarians and vegans to combine specific protein foods at one sitting to make complete protein.
Complementary Protein Theory Debunked:
Scientists used to think that vegetarians, and especially vegans, would develop protein deficiency if they didn’t get eight or nine essential amino acids all together in proper amounts at every meal.
Frances Moore Lappé, author of ‘Diet For A Small Planet’, is well known for the theory of combining complementary proteins at each meal. In the 20th Anniversary Edition of her book, she has altered her views in light of new knowledge about amino acid storage.
Whenever we eat, our body deposits amino acids into a storage bank, and then withdraws them whenever we need them. So, it’s no longer considered necessary to eat complementary proteins together at one sitting, to make complete protein. Your body does that automatically, from all the foods that you eat over the course of a day or so.
We still need a healthy variety of good protein building foods, so the body can make enough complete proteins to be happy, even though you don't need to worry about how and when you combine them.
What Vegetarians Should Eat To Get Enough Protein:
Each plant food has its own unique amino acid profile, from green leafy veggies to tubers, from barley to quinoa, from lentils to tofu, from macadamias to brazil nuts. By eating a variety of plant foods with 'incomplete proteins' throughout the day, we can easily get enough 'complete protein.' For lacto and ovo-lacto vegetarians, any food can be complemented by the high quality proteins in dairy products or eggs, but it isn't at all necessary to include animal foods to get enough protein in your diet.
Your body puts together amino acids from plant foods to give you complete protein throughout the day. For instance, the amino acids in beans & lentils are balanced by those in grains, nuts and seeds, and vice versa.
Vegetables and fruits also contribute significant amounts of protein. A one cup serving of avocado, for example, has 3 grams of protein, and a medium potato with skin has 4 grams.
Vegans and vegetarians can't help getting all the essential amino acids, through eating different combinations of grains, legumes, nuts & seeds, vegetables & fruit several times throughout the day.
Eating for complete protein isn't a scientific system of food combining, where you have to keep track and analyze everything you eat. It's a natural traditional way of eating, which most human beings have thrived on, for thousands of years. Food is a sensual pleasure, and complete protein is a side benefit.