weight loss and healthy eating resource

Why Vegetarian Diet Is Not Sustainable

Why Vegetarian Diet Is Not Sustainable

Vegetarianism and veganism have become popular fads in the diet scene. If religious compulsions once used to be the main reason for such diets, ethical and environmental concerns are driving the new age dalliance with these drastic diets. Everybody has a right to his/her own convictions, but a vegetarian diet in general is both unsustainable and unhealthy for the very reason that humans have evolved as omnivores. We are meant to derive our nutrition from a mixture of animal proteins and fats and easy-to-digest plant parts.

Our dentition, as well as the anatomy of our gastrointestinal tract, clearly shows that we are adapted for an omnivorous diet. We do not have large rumen or caecum for storing plant materials and getting them broken down by millions of microbes. We neither chew cud like cattle, nor eat our own excreta like rabbits, for a second chance at digestion and absorption of nutrients contained in the partly digested plant materials.  

There are several people who toy with vegetarianism/veganism for a while and then start adding back animal proteins one by one. In case of adults, most of the dietary deficiencies get resolved within a short period, but their impact on children can be far reaching. The natural development of children and young adults can be stunted for life even with a few years of protein deficiency. It is not fair to put them at risk of mental and physical development problems.

It is not nutritionally superior

Many people shift to vegetarian or vegan diet thinking that they are nutritionally superior. There has been a general feeling that foods of animal origin are harmful to us because they contain cholesterol. We have been sensitized to the cholesterol issue and its cardiovascular implications so well that even meat-eaters think that vegetarian diet is far better than what they eat. Another misconception is that vegetarians live much longer.

Animal proteins are complete proteins because they come from tissues very similar to ours. They contain all the essential amino acids in the right proportions. These amino acids are required not only for building up our muscle tissue but for many metabolic functions as well. Vegetarian sources of proteins include legumes and nuts. But they are not complete proteins because they do not have all the essential amino acids. So you need to have a combination of pulses and grains to get all the nutrients that you require. You need to do a lot of homework and planning to bring a vegetarian/vegan diet nutritionally comparable to omnivorous diet.

About dietary cholesterol

There have been a lot of misconceptions regarding dietary cholesterol. Animal tissue contains cholesterol because it is an essential component of all animal cells, including those of humans. That means our body needs cholesterol. It is required in the cell membranes; it is part of steroids and hormones; you need it to make vitamin D.

Too much cholesterol in the blood may cause atherosclerosis or deposition of fats on the walls of the blood vessels, increasing the risk of heart attacks and strokes. The cholesterol carrying lipoproteins are of two types: the high density lipoproteins (HDL) and the low density lipoproteins (LDL). High levels of LDL causes their deposition on the arteries, but the HDL cleans up these blood vessels. The aim should be to keep LDL low and HDL high.

Body has a natural mechanism to make the cholesterol it requires. Abnormalities in this mechanism can result in an elevation of blood cholesterol whether you are a vegetarian or not. Dietary cholesterol may not matter as much as we think. Some types of animal fat, especially the omega 3 fatty acids in oily fish is particularly useful in increasing the good cholesterol (HDL). 

Reduced bioavailability of nutrients

The vegetables and fruits in the vegetarian diets are valuable for the water soluble vitamins in them. They are full of many other nutrients that our body requires, but they are not that easily absorbed into the body. Their high fiber content and the difficulty in digesting the plant materials are to blame.

While vegetarians get some amount of proteins from dairy products, vegans are almost completely dependent on legumes. Both these foods are poor in the bioavailability of nutrients and cannot compare to animal sources of wholesome proteins such as fish, meat, chicken and egg.  

Heavy dependence on soy protein

Where do vegans get their proteins? We cannot do without this macronutrient. Heavy dependence of protein supplements, a majority of them derived from soy has been the mainstay of vegan diet. This magic bullet was earlier considered the healthiest food available, and was processed into umpteen food supplements, including soy bacon for those who still missed meat. But that was until the negative effects of soy on hormonal balance came as a shock.

Soy was among the traditional foods of the Chinese and the Japanese for ages, but it was mainly used in its freshly cooked or fermented forms. As the highly processed soy flour from the dry soy beans contain phytoestrogens that mimic the estrogen produced in our body, it can wreak havoc with our hormonal balance. This can be particularly dangerous for children.

Presence of antinutrients

Apart from soy products, vegetarian/vegan diets contain large amounts of grains and pulses. They are both seeds that plants produce to continue their future generations. They are usually very high in anti-nutrients such as phytates.

Lacking in important nutrients

Vegans as well as vegetarians are prone to several nutritional deficiencies such as B12, calcium, iron and zinc. They miss out on the fat soluble vitamins such as A and D, and highly beneficial fatty acids EPA and DHA.

·Vitamin B12

B12 deficiency is a great concern in vegetarians and vegans because 83% vegans and 68% of vegetarians are found to have this problem. This vitamin is important in DNA synthesis and red blood cells formation. Since it is essential for healthy myelin sheath covering of nerve fibers, its deficiency can result in memory loss and lethargy, besides anemia and general weakness.

Children who experience vitamin B12 deficiency during the first 6 years of life may not recover from the resulting cognitive and memory problems even after they take animal products later.

Fermented soy, seaweed, brewer’s yeast and spirulina are considered possible vegetarian sources of B12, but they actually contain cobamides that are analogous to B12, but not the same.

·Vitamins A and D

These vitamins are fat soluble, and are found in abundance in animal products such as eggs, seafood, dairy and organ meats. Carrots are generally thought to be a good source Vitamin A, but in reality, they only have a precursor of the vitamin known as beta carotene. To help the body make sufficient amounts of the vitamin from carrots, you may need to have 2 cups of carrots a day. On the other hand, just a weekly serving of liver would provide enough of the vitamin.

As for Vitamin D, it is essential for proper calcium metabolism and immune functions. It has cancer protecting and anti-inflammatory properties. Certain types of mushrooms are found to be an excellent vegetarian source of Vitamin D, but their availability is not be dependable.

·EPA and DHA

These long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are known to have a beneficial effect on cardiovascular function and protection from degenerative diseases like Alzheimer’s. Seafood, particularly oily fish and shrimp are rich sources of the above.

Although short-chain omega-3 fatty acids alpha-linolenic acid (ALA) found in plant foods such as flax seeds can be converted to EPA and DHA, this function is extremely inefficient in humans, more so in men than in women. So vegetarians and vegans have to consume a lot more of omega-3s to derive the same benefit.


Traditional vegetarian communities have a relatively high intake of dairy products that protect them from calcium deficiency, but vegans are not so lucky. Leafy vegetables such as spinach are thought to be rich in calcium, but its bioavailability is very poor. For instance, you may get more calcium from a glass of milk than you would from 16 spinach servings. Moreover, antinutrient substances such as phytate and oxalate may further reduce its assimilation.


Meat, particularly organ meat such as liver, is a great source of iron, but vegetarians and vegans miss out on this important mineral. Not only that, if they are taking calcium supplements, it can further reduce the absorption of iron.

Is it unethical to eat animals?

It is a question that can only be answered by our personal sensibilities. The crowded and inhuman conditions in which animals are reared and slaughtered on large-scale farms are despicable by any measure. Killing animals for sport is condemnable, but what about imprisoning them for our entertainment, be it in circus, zoo, equestrian sports or as pets?

Most cultures consider killing for food as part of survival; it is about playing our role in the food web. But people who find it unacceptable have the choice of embracing vegetarianism or veganism, but they have to be extra careful about their nutrition. Be aware of potential deficiencies and include necessary supplements to safeguard against them.

Not as environment-friendly as you think

Vegetarianism reducing environmental impact of food production is myth. People who are into sustainable living and making their own food know this very well.  You have better chances of meeting your nutritional needs if you keep some chickens and a cow along with growing vegetables and food grains in your limited plot of land. The stories of early settlers or homesteaders of the American prairies are typical examples. Even when they had 10 acres or more of land to cultivate, they often had to go hungry until they saved enough to buy livestock who could provide them with eggs, milk and occasional treats of meat.  

We could say that all the land used for grazing cattle can be converted into agricultural land for growing more vegetables, grains and pulses. The reality is that, we cannot convert plant materials into energy as efficiently as herbivorous animals can. So our place in the food chain comes after them. Foods of animal origin are concentrated forms of nutrition; a little goes a long way. A vegetarian/vegan has to consume a lot more food to make the same amount of nutrients available to the body.

If a vegetarian/vegan requires additional food supplements such as sea weeds extract to minimize their nutritional deficiencies, it increases their food miles. 

Do you live longer with vegetarian diet?

There are some studies that show vegetarians to be enjoying longer life spans. But that may not tell the whole story. Some communities insist on their members following a vegetarian diet for religious reasons. They may not have higher life expectancy unless they have rituals that promote healthy lifestyle as well.  

People who consciously choose a vegetarian/vegan diet are generally health conscious. So their other health promoting lifestyle measures such as moderation in eating, abstinence from smoking and drinking, and regular exercise may reflect in their longevity. Statistics comparing them to equally health conscious omnivorous people may not show any significant difference in longevity.

Read more