Adipose tissue provides endocrine energy. Leptin factor, estrogen and interleukin secreted by adipose tissue participate in physiological processes such as metabolism, immunity, growth and development.

In the face of cold and hunger, replenish energy to the body.

Promote the absorption and utilization of fat-soluble vitamins such as vitamin A/E.

Protect internal organs, promote gastrointestinal peristalsis, lubricate and protect skin.

Fats include triglycerides, phospholipids and cholesterol, and fatty acids we often say are their components, which can be divided into saturated fatty acids and unsaturated fatty acids according to saturation.

Foods with high phospholipid content include egg yolk, liver, soybean, wheat germ and peanuts.

Foods with high cholesterol content include viscera such as animal brain, liver and kidney, milk, meat and eggs.

Generally, vegetable oil contains more unsaturated fatty acids (peanut oil, corn oil, soybean oil, etc. ), animal oil contains more saturated fatty acids (butter, lard and tallow), but there are exceptions, such as cocoa seed oil, coconut oil and palm oil.

Adult fat absorption rate can reach 95%, which is the nutrient element with the highest absorption rate in human body. Generally speaking, liquid vegetable fat is more digestible than solid animal fat.

The digestion of fat in the stomach is limited, mainly in the small intestine. Hydrolyzed into glycerol, short-chain and medium-chain fatty acids, absorbed by small intestinal cells, and then re-synthesized triglycerides. After entering the blood, it forms large particles of very low density lipoprotein with phospholipids, cholesterol and protein, and is finally absorbed by the liver.

In the past, some scholars thought that cholesterol was related to hyperlipidemia, atherosclerosis and coronary heart disease, but recent studies showed that cholesterol intake was not related to the onset and death of coronary heart disease.

Therefore, healthy people can no longer strictly limit cholesterol intake, unless they are cholesterol-sensitive people and people with metabolic disorders (diabetes, hyperlipidemia, atherosclerosis, coronary heart disease, etc.). ), and these people must strictly control the intake of dietary cholesterol and saturated fat.

From the content of essential fatty acids, vegetable oil is superior to animal fat.

Judging from the content of fat-soluble vitamins, vegetable oil, especially the germ oil of cereal seeds, is rich in vitamin E; Animals' subcutaneous fat contains almost no vitamins, while visceral fat is rich in vitamins A and D, especially marine fish.

Alaska's diet is rich in energy, fat and cholesterol, but the prevalence of cardiovascular diseases is very low, which may be related to the intake of seafood rich in polyunsaturated fatty acids. )

Judging from the ratio of various fatty acids, some studies recommend that the ratio of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids should be 1: 1: 1, while Japanese scholars suggest that it is more appropriate to be 3: 4: 3.

In a word, it's best to eat a little of everything and don't overdo it.

In 1980s, scientists hydrogenated vegetable oil, which changed the spatial structure of unsaturated fatty acids from cis to trans, because they were worried that saturated fatty acids in animal fat would increase the occurrence of cardiovascular diseases, and vegetable oil was unstable at high temperature and could not be stored for a long time.

Trans fatty acids do not have the biological activity of essential fatty acids. Studies have found that trans fatty acids can increase low-density lipoprotein cholesterol, reduce high-density lipoprotein cholesterol levels, increase the risk of coronary heart disease, and induce diseases such as tumors and type 2 diabetes.

In 20 13, the US Food and Drug Administration announced that artificial trans fatty acids harmful to human health were initially banned. Dietary Guidelines for China Residents defines trans fatty acids in the diets of children and adults over 2 years old as 1% of total energy, which is about 2g.

1g fat will provide 9 calories for the body, and the China Nutrition Society recommends that adult fat intake should account for 20%~30% of the total energy. If you consume 1800 calories a day, you need to consume 40g~60g of fat. Generally speaking, as long as you pay attention to eating a certain amount of vegetable oil, it will not cause the lack of essential fatty acids.

Although saturated fatty acids can increase the level of low-density protein in blood, which is related to the occurrence of cardiovascular diseases, it is not easy to be oxidized to produce harmful substances, but also contributes to the formation of high-density protein (a small helper to make low-density protein return to liver metabolism and reduce the content of low-density protein in the body), so the human body should not completely limit the intake of saturated fatty acids.