The age-old debate on adequacy of dietary protein in a vegetarian diet vis-a-vis a non-vegetarian diet is still on.
What we eat is critical to ensure enough required amino acids — the building blocks of proteins that perform critical functions in our body. The popular view is that only a non-vegetarian diet provides all the important amino acids, while a vegetarian diet often lacks adequate protein.
However, several nutritionists and research studies have busted this myth by concluding that vegetarians can easily get the specified amino acids/proteins from a plant-based diet and dairy products.
A plant-based vegetarian diet is very good for a healthy life as it saves you from chronic illnesses, says Nilanjana Singh, a consulting nutritionist based in New Delhi.
“If you are consuming peas, beans, nuts, and seeds, you will be fine,” Singh says. She, however, recommends having dairy products like milk, curd, and paneer along with plant-based foods to get all the required amino acids.
For an average Indian adult, 0.8-1 gm protein/kg body weight/day is adequate to meet the basic nutritional requirements, according to Indian Council of Medical Research recommendation.
The human body needs 20-22 different amino acids for growth, development, and to carry out various functions. The protein is broken down into amino acids, which are then used for the body’s upkeep and regulating its various functions at the cellular level – such as to produce neurotransmitters, hormones, and growth of muscle.
Of the 20 amino acids, nine are essential. Since our body does not make the nine essential amino acids or AAs, we need to get them from diet. The rest 11 AAs are non-essential and can be produced by our body, even if we do not get them from the food we eat.
The nine essential amino acids are histidine, leucine, phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, and lysine.
The bioavailability dilemma
Dr Pallavi Aga, MD, doctor and lifestyle consultant, says lack of good quality protein can lead to loss of muscle mass, osteoporosis, low energy, and chronic fatigue and can ultimately lead to lifestyle diseases such as diabetes. Insufficient protein in the diet also leads to low satiety, which causes increased consumption of food or a drop in metabolism leading to either anorexia or obesity.
According to Dr Aga, one cannot get the entire profile of amino acids by eating only a plant-based diet. Most of the plant-based protein has poor bioavailability and lacks many micronutrients. The protein in eggs has a bioavailability of 100, unlike beans and wheat that have a bioavailability of about 49 and 54 respectively.
Bioavailability is the absorption, digestibility and utilisation of a particular protein into the body. Any nutrient’s bioavailability is directly proportional to the positive impact it has on our overall health. Low bioavailability of any nutrient can lead to its deficiency in the body.
“Those who depend on legumes/ lentils to fulfil their protein requirement should realise that 100 gm of lentils have more carbohydrates than 100 gm of whole eggs. The protein to carbohydrate ratio should always be high in whatever food we consume for protein requirements,” says Dr Aga.
Busting a misconception
She recommends that vegetarians should increase their consumption of dairy and good quality milk and ghee, especially those derived from A2 cows. Egg yolk has best possible micronutrients within it.
However, Ruchika Dawar, a Bengaluru-based holistic wellness coach, says humans do not require animal-based protein for their amino acids.
“Our day-to-day requirements of amino acids can be met through plant-based diet like the staple Indian dal-rice. Individuals with very high protein needs can also have plant-based foods like tofu, chickpea, etc, which are full of all the essential amino acids minus animal fat,” she says.
Plant-based proteins that do meet the requirements for essential amino acids include soy (27 percent), brown rice (28 percent), pea (30 percent), corn (32 percent), and potato (37 percent).
Milk protein (39 percent) and calcium caseinate (38 percent) showed an intermediate amino acid content, while casein (34 percent) and egg (32 percent) showed a lower essential amino acid content.
Ishi Khosla, a practising clinical nutritionist, demystifies the assumption that plant proteins have lower digestibility and absorption as compared to animal protein, which makes them inadequate. According to her, absorption issues are there because of the gut. The food habits over the years have made changes to the gut to make it leaky, Khosla says.
However, the gut can be made healthy and efficient again by making diet changes and having certain other essential micronutrients, she adds.
The case for first-class proteins
Growing children, pregnant women, lactating mothers, people undergoing post-surgery recovery, and those experiencing high stress levels need first-class proteins, says Singh.
First-class proteins have all the essential amino acids and are obtained from meat, fish, poultry, and dairy products. Second-class proteins contain some of the amino acids. Seeds, nuts, vegetables, legumes etc fall under second-class proteins.
Seema Sharma, 48, a banker in New Delhi, became very weak and frail after she had an emergency surgical procedure a few years ago. The doctor asked her to increase the intake of essential amino acids for a quick recovery. Sharma, a vegetarian, supplemented her diet with dairy products.
Ruchi Jain, 45, a homemaker in Noida, was also asked to include eggs and chicken in her ten-year-old son’s diet. His tennis coach recommended it to help increase his height, enhance his performance, and provide extra energy during playtime. She started giving him nuts, sprouts, soy, pulses, paneer, dates, fruits and milk regularly. Her son would also have egg occasionally. Her elder son, 18, is a runner and consumes whey protein, derived from cow milk.
Getting the mix right
Khosla says, “Plant based diet fulfils all your protein needs in absolute terms.” She adds the trick lies in making the right combinations and permutations of different food items with each other to get all the necessary amino acids.
According to Singh, if someone is averse to meat and fish, they must have milk products along with beans, seeds, nuts and whole grains.
“Dietary choices cannot be forced upon people. Vegetarians can have all the right amino acids by combining various foods. It is like a jigsaw puzzle where right combinations are very important,” she says.
Singh says, “Rice and dal [lentil] is a very good combination to have all your amino acids. For every three spoons of rice have one spoon of lentil or dal to have more amino acids. Rice contains cysteine and methionine but is low in lysine while lentils are low in cysteine and methionine but high in lysine. Therefore, combining them gives you a complete protein.”
Legumes and nuts
A study Dietary protein and amino acids in vegetarian diets conducted by François Mariotti and Christopher D. Gardner and published in 2019 by the US National Institutes of Health pointed out that protein-rich foods, such as traditional legumes, nuts and seeds are sufficient to achieve full protein adequacy in adults consuming vegetarian or vegan diets, while the question of any amino acid deficiency has been substantially overstated.
Dr Gopal Sharma, an oncologist at Max Super Speciality Hospital, Vaishali, says, “Vegetarians should consume more of barley, wheat, millet, quinoa, chia seeds, hemp seed, amaranth, pumpkin seeds, cottage cheese, tofu, edamame etc to get an adequate amount of essential amino acids.” He also emphasises combining different foods.
Vegetarians have several options available to obtain amino acids from plants and dairy products. What is important is to eat foods by pairing them in correct proportions to get the maximum benefit.
The same NIH study recommended that “further study on protein in vegetarian diets shift away from unnecessary questions about protein adequacy, to a comparison of overall nutrition quality and implications for long-term health with plant-based protein-rich foods vs. animal-based protein rich foods.”