Searching for Essential Amino Acids.
PKGhatak, MD
Essential amino acids for humans are 9 in number, namely: Histidine, Isoleucine, Leucine, Lysin, Methionine. Phenylalanine, Threonine, Tryptophan and Valine. Essential amino acids must be supplied in the food because our body can not synthesize them from other sources. Our body however can synthesize these non–essential amino acids, and common among them are Glycine, Alanine, Serine, Cysteine, Arginine, Aspartic acid, Glutamic acid, Arginine, Lysine, Tyrosine, Proline and Homocysteine. Amino acids are the main building blocks of protein molecules.
The human body is composed of 62 % water, 16% fat, 16 % proteins, 6 % minerals, 1 % carbohydrates and traces of vitamins and trace elements.
The function of Amino acids.
Both essential and nonessential amino acids are constituents of every cell and tissue of our body- from hair to the bone marrow cells and in between everything else. In addition, amino acids are required for growth, tissue repairs, immunity, hormone production and metabolic functions.
A few specific functions of individual amino acids are highlighted in the following paragraph.
Histidine - Blood cell formation.
Isoleucine - Increases growth hormone production. Skin and bone repairs.
Lysine - Calcium absorption, Collagen formation of tendons, cartilages, and skin.
Methionine - Antioxidant. Detoxify heavy metals.
Phenylalanine – Formation of the neurotransmitter, calcitonin and melanin. and also the source of Tyrosine.
Threonine - Formation of elastin, the enamel of tooth and mucin production from glands. Glucose metabolism.
Tryptophane - Formation of serotonin and melatonin, DNA repairs, Niacin ( vitamin B3).
Valine – Muscle growth and health.
Are humans omnivorous.
There is no other living organism that exists today that comes close to humans in choosing what to eat – from insects to the most poisonous puffer fish and snakes.
According to the WHO in the year 2021, a family of four in the USA consumed. 800 lbs of meat per month. 70 lbs of chicken per person per month was eaten during that time.
350 million tons of meat was consumed globally every year, of which pork was number one. China produced and consumed the most pork, and the USA came in third place. The USA is the largest consumer of beef and India came 5th place; that must surprise some people. Fish consumption is highest per capita in Iceland, at about 200 lbs per year, the USA came 11th place by using 50 lbs per capita and still managed the second place by eating 290 eggs per person, only Japan consumed more, about 320 eggs per person.
The current trend in the USA.
In recent years vegetarian diet has gained popularity among the health and environment conscious sections of the wealthier nations. Various degrees of vegetarianism exist. True vegetarians or vegans do not eat any meat or fish and avoid eggs or milk altogether. In India where a major section of the population has been vegetarian for centuries, however, they consume milk from the cow, buffalo, goat and a few isolated tribes drink milk from camels. Some other Indians consider themselves vegetarian but eat eggs and some also fish but not any animal meat.
Whatever form of vegetarian one may be, the main source of protein in their diet comes from plants. And most green parts of plants are not rich in proteins, the seeds of plants are. In order to meet the demands of plant seeds that are rich in proteins, more selective cultivation is required. It is becoming an important agricultural consideration for meeting this growing demand but must be met in sustainable and environmentally protective ways.
Protein requirement.
A growing child in utero needs 925 gram of protein and the mother supply that amount during pregnancy. During lactation additional 1.3 grams of proteins per 100 ml of milk is needed.
Adults require 0.8 grams/Kg body weight ( stand height/weight). The elderly actually needs less but defects in digestion and absorption are considered and the recommendation is like an adult - 0.8gm/Kg.
Obligatory Nitrogen Loss.
Protein turnover in the body is a continuous process of synthesis, breakdown and elimination of toxic nitrogenous waste products. When placed in a protein free but calorie sufficient diet, the body extracts the essential amino acids by breaking down proteins. This system is very efficient but the nitrogenous portion that is eliminated in urine and stool must be supplied in the food.
Effects of protein starvation.
Pictures of emaciated people ravaged by wars or severe famine need no further explanation. A short stature of a growing child, thin limbs, a pot belly, edema, fragile skin and orange hairs are the results of protein deficiency. Blood levels of albumin and hormones are low in these children. In nephrotic syndrome and severe liver cirrhosis, frequent infections and various complications are the results of derailed protein metabolic machinery of the body. Specific amino acid deficiency can occur due to inherited metabolic defects and the consequences of those can be found elsewhere.
Plant Proteins.
Many plant proteins are not available to humans due to the complex nature of the molecules which are not easily digested or absorbed in the gut. Some plant proteins are poisonous like in cassava.
Good source of vegetable proteins.
The high plant protein content is given here in descending order. It is the total amount of available protein but not in terms of essential amino content. The list of the plant source of proteins: Durham wheat, cashew nuts, quinoa seeds and ancient grains, dried seaweeds, rice, pumpkin seeds, beans, peas and raw soya beans.
Some individual plants with some good sources of essential amino acids are listed as -
Durham wheat supplies a fair amount of histidine, phenylalanine, tryptophan, valine and threonine.
Cashew nuts are a good source of phenylalanine, valine, leucine, lysine, Isoleucine and methionine.
Pumpkin seeds supply phenylalanine, tryptophane, Isoleucine, leucine and threonine.
Quinoa and ancient grains. Quinoa contains all 9 essential amino acids. Several other ancient grains are also good sources of proteins chief among them are barley, farrow, buckwheat, millet, sorghum, kamut and teff. Each one has many other health benefits. Quinoa is an annual herb, that belongs to the Chenopodium family. The grain contains 8 grams of protein per cup of cooked grain and is highly sought after because they supply all nine essential amino acids. The protein of quinoa is 11s-globulin and contains no gluten. In addition, quinoa supplies unsaturated fatty acids, flavonoids, vitamins and minerals.
The rest of this group of grains contain more or less the same amount of proteins and are good sources of essential amino acids but the amount varies from one to the other. All are good sources of micronutrients and antioxidants.
Soya beans have a good amount of leucine, lysine and phenylalanine.
Seaweeds are rich in histidine, leucine and lysine.
Peas and beans also supply fair amounts of phenylalanine, valine and threonine.
The world is always changing, and the rate of change has accelerated greatly in the last two or three centuries. The younger people of the present generation are much more concerned with animal sources of protein food along with other climate concerns. Eating proteins from nonanimal sources has come to attention lately from the processed food industries. This may be good or bad, only the future will tell.
Observing the effects of mass tourism causing accelerated degradation of the environment, like what has done to Vienna and the Galapagos islands, should ring an alarm bell about this mass movement. No one can predict what that would do to the forested land in order to meet the demand for plant protein for human consumption.
*********************************************
