Without cholesterol, where would sex hormones come from? How would humans reproduce?
Expert: He Jiguo, Director and Associate Professor of the Department of Nutrition and Safety, College of Food Science and Engineering, China Agricultural University.
Nutrients are vital substances for maintaining life activities. Different nutrients have different functions, but they generally fall into three categories: providing energy, forming body tissues, and regulating physiological and biochemical reactions in the body.
Macromolecular substances such as proteins, lipids, and carbohydrates can provide energy to maintain the body's energy expenditure. The body's energy consumption is mainly used for basal metabolism, physical activity, and the specific dynamic effect of food. In children, it also includes growth and development. Basal metabolism is the most basic energy requirement to sustain human life, including maintaining normal heartbeat, breathing, glandular secretion, etc. For a person with moderate physical labor, basal metabolism accounts for about 50% of energy expenditure and is the main part of the body's energy consumption. Therefore, compared to others, many people find that they don't eat much and work a lot, but they are still fatter than others.
Basal metabolism is mainly influenced by factors such as genetics, body type, endocrine status, and nutritional status. Except for genetic factors, which cannot be changed, other factors can be modified through adjustments in exercise, diet, etc. For example, exercise can change body type and increase basal metabolic rate by strengthening the heart and respiratory muscles. Physical activity is another way the body expends energy. The energy expenditure of physical activity is related to the intensity and duration of the activity; the greater the intensity and the longer the duration, the greater the energy consumption. In addition, it is also affected by proficiency and level of attention. For the same activity, a skilled person will have lower energy consumption, while when one feels they are being watched, they often become tense, which also increases energy consumption.
The specific dynamic effect of food refers to the additional increase in energy expenditure caused by eating. The energy entering the body is often lower than the energy contained in the food consumed. This is because the digestion and absorption of food in the gastrointestinal tract also requires energy. On one hand, food digestion requires the body to produce digestive enzymes, and the synthesis of these enzymes consumes energy. On the other hand, the absorption of digested products such as amino acids, glucose, calcium, iron, etc., requires the help of carriers, which is also an energy-consuming process.
Nutrients such as proteins, lipids, carbohydrates, calcium, and phosphorus are also components that make up the body's tissues. Protein is the main component of the human body, and the composition of muscles, bones, etc., requires the participation of protein. Lipids are the main component of cell membranes. Besides forming cartilage, carbohydrates are also a marker component of cells. Calcium and phosphorus are the main components of bones. Another important function of nutrients is to regulate and control the body's physiological and biochemical reactions. Enzymes made of proteins are catalysts for the body's physiological and biochemical reactions. Under the mild conditions in the human body, no reaction can proceed without the catalysis of enzymes. Proteins and cholesterol can form hormones, which play a huge role in regulating and controlling the body's physiological and biochemical reactions. Especially cholesterol, it is a nutrient that we have misunderstood. Just think, without cholesterol, where would sex hormones come from, and how would humans reproduce?
The idea that cholesterol causes coronary heart disease is a misappropriated concept. When we talk about foods high in cholesterol, we are referring to the chemical substance cholesterol. However, when we talk about causing coronary heart disease, we are referring to lipoproteins. This is because when translated from English, some people translated lipoproteins as "lipoprotein cholesterol," such as low-density lipoprotein (LDL) being called "low-density lipoprotein cholesterol" and high-density lipoprotein (HDL) being called "high-density lipoprotein cholesterol." Because HDL has the effect of reducing the risk of coronary heart disease, it is also called "good cholesterol." Whereas LDL increases the risk of coronary heart disease, it is called "bad cholesterol."