Plant based diet: Food sustainability and health

There is growing concern over increasing world population. One WHO report (1) says that world population of 7.6 billion in 2017 will reach 8.6 billion in 2030 and 9.8 billion in 2050. The largest growth of population in the period will be in just nine countries in which India will be on the top position. High population growth means more mouths to feed. More land is used for agriculture which will lead to issue of deforestation. We need to find sustainable ways of eating our foods. If world adopted a plant-based diet, usage of global agricultural land will reduce from four to one billion hectares. (2) Animal foods mainly require land for raising the livestock. It will be as high as 100 times than to produce Kcal of beef or lamb versus plant-based alternatives (Fig 1).

Figure 1

This underlines the importance of shifting to Plant-based diets to avoid possible world food scarcity. It is worthwhile to evaluate effects on nutrition and health of the people triggered by such a shift.

Plant-based diets are classified as follows:

Vegan: Excludes animal products, no restriction of consumption of whole foods or restrict fat and sugar.
Raw food, Vegan: Exclusions same as Vegan and, also excludes all foods cooked at more than 48 degree centigrade.
Lacto-vegetarian: Excludes animal products except milk products.
Ovo-vegetarian: Excludes animal products except eggs.
Lacto-Ovo-vegetarian: Exclude animal products except egg, milk products.
Whole foods, Plant-based, fat restricted: Plant foods in whole form, vegetables, fruits, legumes, seeds, and nuts (smaller amounts)
Mediterranean: Like whole foods plant-based diet, small amount of chicken, dairy products, eggs, red meat once or twice in a month, fish, olive oil encouraged, no fat restriction.

Major micronutrient of the diet are proteins and are required at all stages of life. Responsible for the muscle mass and part of numerous critical biological processes of the body. Proteins are received from animal as well as plant sources. Common animal sources are milk, cheese, eggs, beef, poultry, goat, lamb, pork, fish. In case of plant proteins, whole grains, lentils, oil seeds, nuts are some of the sources. (3)

The superiority of animal protein quality is beyond doubt. They lack certain Essential Amino Acids (EEAs). They have poor digestibility and bioavailability of amino acids and minerals, because protein is enmeshed with fiber and other plant components, and anti-nutrients. There are ways to improve intake of EAAs. Indian traditional diets take care of the deficiency of EAAs. When the combination of rice-dal or roti-dal is consumed, the complementary effect gives the quality protein (Rice, Wheat are deficient in Lysine whereas, Dal is deficient in S containing AAs). Consuming plant protein isolates/concentrates or consuming more quantities of plant proteins will also help. Consumption of animal proteins can lead to heart disease because of saturated fat in red meat. Saturated fats can also cause certain types of cancer and strokes. The plant proteins score better over animal proteins in health benefits like reduction of risk of NCDs such as Cancer or Heart attack. When consumed, give phytonutrients like isoflavones, carotenoids. They are less damaging to kidneys.

Another macronutrient of importance are carbohydrates which are major source of energy for us. We receive carbohydrates from Cereals like rice wheat, corn, millets in the form of starches. Whole grains (4) when consumed also give many nutritional components like bran (fiber, omega 3 fatty acids, vitamins, minerals), endosperm (starch), germ (vitamin E, folate, thiamine, phosphorous, calcium). Other nutrients offer several health benefits like protection against heart disease, type 2 diabetes, cancer, weight management. Millets are gaining importance because of their ability to grow in very extreme climates. They have potential, in view of rising temperatures, frequent draught. They have relatively high content of proteins as compared to cereals, good source of vitamin B including folate, source of many cereals such as iron, magnesium, copper, zinc, phosphorous.

Fats are macronutrient giving one third or one fifth of daily calorie needs. They carry and help to absorb many fat-soluble Biomolecules. Vegetarian sources are healthier as compared to that from animal source like lard which are rich in saturated fatty acids. Commonly consumed (5) oils in India like Peanut, Soybean, Safflower, Sunflower, Mustard do contain saturated fatty acids but the amount is less (less than 20%). They also contain MUFA and PUFA which may not be in desired right ratio. This can be sorted out by intermittently changing the source of cooking oils. Palm oil contain higher amount of Saturated fat (44%) but also contain high amount of MUFA (43%). Similarly, Coconut oil which contain 92% of saturated fats of which 59% is contributed by MCT which do not raise cholesterol. They lack in Omega 3 fatty acids. This can be fulfilled by unconventional seeds like flax seeds. Spices and nuts are also rich sources. Wheat, pearl millets, some pulses, vegetables, and fruits also contain omega 3 fatty acids.

One needs to be cautious for certain micronutrients (6) while consuming Plant-based diets. The bioavailability of iron in plant plant-based diet is lower than meat. Vitamin B₁₂ deficiency is common and need to supplementation with B₁₂. Calcium intake can be adequate in a well-balanced plant-based diet. Some significant sources of Calcium include, tofu, mustard and turnip greens, spinach. Plant-based diets should be fortified or supplemented with Vitamin D for those who are found deficient.

As more and more people shift to plant-based diet, it will be helpful to people to live healthy life which will be less of NCDs. It will simultaneously resolve the serious impending issue of food sustainability considering growth of world population. Plant-based diets are future source of foods for the mankind.