Proteins are large biological molecules, or macromolecules, consisting of one or more chains of amino acid residues.
Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle.
Proteins are also necessary in animals’ diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.
The nine essential amino acids are histidine, isoleucine, leucine, lysine, L-tryptophan, methionine, phenylalanine, threonine, and valine. Additionally, cysteine (or sulphur-containing amino acids), tyrosine (or aromatic amino acids), and arginine are required by infants and growing children. Also, the amino acids arginine, cysteine, glycine, glutamine, proline, serine and tyrosine are considered conditionally essential, meaning they are not normally required in the diet, but must be supplied to specific populations that do not synthesize them in adequate amounts.
Just as insulin serves as a sort of default sugar sensor and leptin serves as the body’s fat sensor, scientists have recently discovered that the mTOR pathway serves as the body’s protein sensor, monitoring the availability of protein, or amino acids, particularly leucine and methionine, for growth and reproduction. It is also impacted by insulin levels in the body. When protein levels are detected that are higher than basic maintenance requirements, the excess up-regulates the activity of the mTOR pathway, stimulating cellular proliferation and adverse mitochondrial effects, affecting the potential longevity of the individual. Increased insulin also has this effect. What is activated is our reproductive and cell-proliferating capacity.
Recent studies have shown that limiting dietary amino acids, especially methionine, inhibits mTOR signalling, which decreases mitochondrial damage and protein translation, resulting in slowed aging and improved health. Cellular proliferation occurs under three circumstances: reproduction, growth and cancer. The American Association of Cancer Research has stated that modified caloric restriction may offer a protective effect against the development of epithelial cancers.
If the amount of protein consumed stays below the threshold that stimulates cell proliferation, then ancient mechanisms kick in, which evolved to help the body outlive an apparent famine, by shutting down cell proliferation and up regulating repair and regeneration. In this case the body’s energy is conserved through maintaining our own cellular repair instead of producing new cells. This is dependent on ingesting just enough protein to meet the demands of our own repair, regeneration, and maintenance needs, which extend our longevity, optimize our health, and possibly reverse aging, without up-regulating mTOR or stimulating excessive insulin levels.
The amount of protein needed to avoid upregulating mTOR is estimated to be roughly 0.8 grams per kilogram (2.2 pounds) of ideal body weight. Click the previous link to access an ideal body weight calculator. The ideal body weight is based on age, height and sex. This calculator is designed for adults 18 or older.
For girls from 2 to 20 years of age use This Chart.
For boys from 2 to 20 years of age use This Chart.
Following are some examples of the daily protein requirement based on different ideal body weights:
100 pound ideal body weight (45 kg) x .8 g= 36 g
125 pound ideal body weight (57 kg) x .8 g = 46 g
150 pound ideal body weight (68 kg) x .8 g= 54 g
175 pound ideal body weight (80 kg) x .8 g= 64 g
These amounts are sufficient for the vast majority of adults, while athletes would require a bit more, somewhere in the neighborhood of 60 to 80 grams per day.
The following foods are sources of incomplete protein but do contribute to the amino acid pool and affect the mTOR pathway:
Nuts (1/4 cup): 5 g
Peanuts (1/4 cup): 9.5 g
Peanut butter (2 tbs): 8 g
Almonds (1/4 cup): 7.5 g
Sunflower seeds (1/4 cup): 6.5 g
Oatmeal (1 cup): 6 g
Black beans (1/4 cup): 4.5 g
Pinto beans (1/4 cup): 3.5 g
Chickpeas (1/4 cup): 4 g
Quinoa (1/2 cup): 4.5 g
Lentils (1/2 cup): 9 g
Tempeh (1/2 cup): 20 g
Brown rice (1/2 cup): 2.5 g
Broccoli (1/2 cup): 2.5-3 g
Spinach (1/2 cup): 2.5 g
Coconut milk (1 cup): 6 g
Primal Body, Primal Mind
Nora T. Gedgaudas, CNS, CNT