Traditional Indian dietary practices got it right centuries ago when legumes, beans, vegetables, yoghurt and grains began being eaten together in one meal. Apart from enhancing taste, mixing food sources also optimises intake of critical nutrients such as protein, which builds and maintains tissue, immune function and nutrient absorption, among other things.

There are several plant sources proteins, but except for soy, most are “incomplete proteins” because they are missing one or more of nine essential amino acids, the building blocks of protein. Since even incomplete plant proteins have some essential amino acids, mixing proteins from different plant sources in the same meal – as is done in most traditional cuisines across regions – makes the dietary protein intake complete to boost health. For vegetarians and vegans, protein complementation is the most efficient way to optimise protein intake.

For example, grains are deficient in amino acid lysine, while legumes and pulses do not have methionine, but combining these food sources, such as having lentils or beans with rice or chapatti, provide balanced nutrition.

For meat-eaters, the best sources of protein are meat, poultry, dairy products, eggs and fish because animal produce naturally contains all the nine essential amino acids — histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine – needed by the body.

Not enough

Vegetarians have a particularly higher chance of being deficit in protein and several other nutrients missing in plant foods, such as Vitamin B12 found mainly in fish, meat, poultry and dairy products; Vitamin D in oily fish, eggs and dairy; docosahexaenoic acid (DHA) in fatty fish; and zinc and haeme-iron predominantly found in red meats, from where it is better absorbed than from non-haeme plant sources.

While much has been written about ion-deficiency anaemia in India – 53.2% of women are anaemic, according to National Family Health-4 2015-16 – protein deficiency in adults is rarely discussed. South Asians particularly need protein because they have low skeletal muscle and lean mass, and a high percentage of body fat, including health-damaging deep subcutaneous and visceral fat, which puts them at higher risk of diabetes and heart disease.

Including protein, in the diet, every day makes up for this natural deficit. Each gram of protein provides around 4 calories, but since it increases satiety by making you feel fuller than carbohydrates and fat over a longer period of time, a high-lean protein diet lowers appetite and leads to weight loss.

On average, one cup of cooked lentils, one glass of milk, or one large bowl of yoghurt have 7-8 grams of protein. A sedentary adult needs about 1 gm of protein/kg of body weight each day. So a person weighing 60kg would need 60 gm of protein, which is about two glasses of milk and one big bowl of cooked lentils for vegetarians; or two eggs and two-three pieces of fish or chicken. People who are physically active need 1.2-1.5 g protein/kg per day, as do older adults who lose muscle mass with age, while pregnant and lactating women about 80gm a day.

 Deficiency alert

Around one billion people worldwide suffer from protein deficiency, which remains high in South Asia because of the largely plant-based diet. When dietary protein is in short supply, the body loses lean muscles to preserve more important tissues and body functions, leading to muscle wasting, which is most common in young children and older persons. Increasing dietary protein can slow the muscle degeneration associated with ageing.

The skin, hair and nails are mostly made of protein, and low amounts can lead to flaking, reddening and depigmentation patches in the skin, thinning hair, hair loss (alopecia) and brittle nails. Protein deficit also lowers immunity, which raises the chances and severity of infections, such as influenza. Even marginal deficit affects the immune response, with a small study showing that older women on a low-protein diet for nine weeks lowered immunity. Severe deficiency causes oedema (water retention) from low serum albumin, which is the most abundant protein in blood plasma, leading to kwashiorkor syndrome and the characteristic bloated belly associated with acute malnutrition.

It’s hard to plan a calorie-sufficient diet that has packed with all the nutrients and micronutrients needed to stay healthy, which makes mixing food sources the easiest way to plan a nutritious meal. For those still struggling with deficits, there’s always supplementation.

Protein sources/100 gm

Pulses (cooked, one small bowl): 5-6 gm

Nuts (20-30): 15-20 gm

Grain (two chapattis, one bowl of rice): 2-3 gm

Milk (half a glass): 3-4 gm

Fish (2-3 pieces): 20-22 gm

Chicken, red meat (one chicken breast, three pieces): 19-20 gm

Egg (one): 8-10 gm

Source: Indian Council of Medical Research