Recently, a friend asked about the effects of frequently consuming beef tallow, mutton tallow, and lard on the body. On this matter, I consulted a nutrition expert.
Sources of Saturated Fatty Acids
Beef tallow, mutton tallow, and lard are mostly extracted from the fat tissues of corresponding animals. Fat is composed of glycerol and fatty acids. Fatty acids include saturated fatty acids and unsaturated fatty acids (polyunsaturated fatty acids and monounsaturated fatty acids). The fatty acids in the fat tissues of four-legged animals like cattle, sheep, and pigs are predominantly saturated fatty acids.
Sources of Unsaturated Fatty Acids
If saturated fatty acids mainly come from the fat tissues of four-legged animals, where do unsaturated fatty acids mainly come from? The fat tissues of two-legged animals like chickens, ducks, and geese contain half saturated fatty acids and half monounsaturated fatty acids. In the fat tissues of legless animals (such as fish) and most vegetable oils (such as soybean oil), the fatty acids are mainly polyunsaturated fatty acids.
The proportion of the three types of fatty acids is key
The fatty acids the human body needs are not just one type, but include three: saturated, polyunsaturated, and monounsaturated fatty acids. It is most reasonable for the human body to consume one-third of each of these three fatty acids daily. Excessive intake of any one type of fatty acid is detrimental to health. In other words, once the proportion of the three fatty acids becomes imbalanced, it will cause immeasurable damage to the body, such as disorders in lipid metabolism, which in turn may lead to disorders in carbohydrate and protein metabolism.
Therefore, it's not scary to frequently consume beef tallow, mutton tallow, and lard. What's scary is consuming only these animal fats, leading to excessive intake of saturated fatty acids and insufficient intake of the other two, causing an imbalance in the proportion of the three fatty acids. The correct approach is to alternate between animal and vegetable oils, either every other day or every other meal.
Balance both proportion and total amount
The human body needs to control both the proportion and the total amount of these three fatty acids. In a reasonable human diet, 20% to 30% of the body's required energy is supplied by fat, with 20% to 25% for adults and 25% to 30% for children and adolescents. The sources of dietary fat include not only the oil in cooking oils and the fat in meat, but also lipids contained in various foods. Therefore, when controlling the proportion and total amount of the three fatty acids within a day or a week, the fatty acids in cooking oils and various foods (such as fatty meat) must all be taken into account. For example, after eating fatty meat, one should consciously reduce the intake of animal fat to keep the proportion and total amount of all fatty acids within a reasonable range.
Are saturated fatty acids "bad" fatty acids?
For people with hyperlipidemia (the culprit behind atherosclerosis), the intake of fatty acids requires attention. It is generally believed that saturated fatty acids have a high melting point and can easily solidify on blood vessel walls, leading to arteriosclerosis, whereas unsaturated fatty acids do the opposite. Therefore, saturated fatty acids are considered "bad" fatty acids, so many people believe that "people with hyperlipidemia should consume less saturated fatty acids and more unsaturated fatty acids." This idea is wrong. An increasing number of studies have confirmed that saturated fatty acids have functions such as regulating lipid metabolism, so they cannot be simply labeled as "bad" fatty acids.
Fatty acid needs for people with hyperlipidemia
The proportion of the three fatty acids in the diet of people with hyperlipidemia should not change; what needs to change is the total amount of the three fatty acids, which should be moderately reduced based on the recommended dietary fat intake for Chinese residents.
The highest state of nutrition is balance. The proportion of fatty acid intake should be reasonable, and the same applies to other foods. It is very difficult to strictly follow proportions in daily meals. The truly practical method is to diversify ingredients every day, with 40 or more being ideal. By achieving overall nutritional balance, local nutritional balance can be reached.