Scientific approach to food
There are three types of digestive systems: herbivores, carnivores (zoophages), omnivores.
Zoophages (carnivores) do not need plant food for the normal functioning of the body. They are naturally able to eat raw meat.
They have claws and sharp fangs to rip flesh apart . There are no molar flat teeth for grinding. The food is swallowed, almost without chewing, because there is no amylase in saliva and the main digestive cycle begins in the stomach. Because of this, their jaw is almost motionless, it can move only up and down.
The stomach of predators secretes a large amount of hydrochloric acid, and the pH of their gastric juice is less than 2. This is a protection from decay. The acid also kills bacteria and parasites that live in the flesh of rotting corpses. Omnivores also have fairly low pH and can eat meat raw.
The digestive tract of carnivores is short (only 5-6 times longer than the body) and straight, almost without any folds. The remains of protein food after digestion in the stomach must be quickly evacuated. If this is not done (that is, if the intestines of these animals were longer), these remailns would begin the process of decaying in the intestines.
Herbivores (phytophages) prefer plant foods. Their teeth are poorly differentiated, there are flat molars for grinding hard plant fibers. While the food is thoroughly rubbed with molars, amylase (enzyme) breaks down vegetable carbohydrates.
The jaw of herbivores can make complex chewing movements - from top to bottom and left and right.
The pH of the stomach is neutral or even slightly alkaline - there is no need to break down protein, and bacteria live on plant food several times less.
The length of the digestive tract of herbivores is 12 horse) times longer than the body, sometimes up to 30 times (sheep) and includes many folds. This structure allows them to live on plant food for a long time, while it passes the entire length of the intestine, and to absorb nutrients through all it's length. Unlike protein food, vegetable food is not subject to decay, but on the contrary serves as a cleansing agent while plant fibers go through all the folds of the intestine, like a brush (especially MCC).
Omnivores (pantofagi) . They can survive on both types of food. The most well known examples are bears, domestic dogs, and raccoons. Half of their diet is vegetarian, the other half - insects and meat. For the latter, they have sharp claws and fangs. Their digestive tract is short, with a distinct acidic environment (able to eat raw meat). Bears and other omnivores, however, chew their food rather than swallow it; they have flat molars.
Man. Full set of flat molars, plus an additional 4 (wisdom teeth). Canines are almost undifferentiated. Saliva contains amylase. The jaw is very mobile, it performs all the movements typical of herbivores jaw. The gastric juice acidity is rather low and varies throughout the day and from one gastric department to another. The intestines of an adult are very long, spiral-shaped, up to 12 m.
Humans are the only animals that cook food. Human cannot eat raw meat, even processed meat often causes illnesses from the slightest contamination with bacteria and parasites.
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A study was carried out in Harward, in which for 5 days half of the subjects were restricted to a plant-based diet, the other half - to meat and dairy foods. The latter group showed a significant increase in the number of gram-negative bacteria Bilophilia wadsworthia, which live mainly in the appendix and are capable of causing various inflammatory diseases, colitis, (fact has been experimentally proven on mice).
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Eskimos, whose food for hundreds of years is only 2 months a year enreached with plant foods, suffer from atherosclerosis, become victims of heart attacks and strokes. 12% of the population is affected by parasites. Average lifetime is 60 years, while in most countries this number has exceeded 80.
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An interesting fact about the human brain is that there are not enough proteins and fats for it's full functioning. In fact, the main substance for its vital activity is high-energetic food, mainly starch. It is found in large quantities in potatoes and beets, sweet potatoes. This is confirmed by a 2016 study published in Quaternary International.
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A 2003 study published by the University of Oxford found that of 37,875 healthy men and women aged 20-97, those who followed a meat diet had an 8.3% higher BMI than vegetarians. In 1994, a Harvard study found that eating meat 5 times a week increased the likelihood of colon cancer. In 2014, it was found that people who ate animal proteins were 4 times more likely to die of cancer.