Dietary Health Guide for Men: Scientific Analysis of Six Essential Core Nutrients

Human Body and Nutrients

Nutrients refer to substances essential for the human body to be digested and absorbed, providing energy, forming body tissues, regulating physiological functions, and carrying out normal metabolism. They are also essential raw materials for the reproduction, growth, repair, and maintenance of organ functions in the human body. Protein, fat, carbohydrates, inorganic salts (calcium, phosphorus, iron, etc.), vitamins, and water are the six essential nutrients for human growth, development, and physiological activities. What are their functions in the human body? How much does a normal person need daily? A brief introduction is given below:

Protein is synthesized from amino acids containing carbon, hydrogen, oxygen, nitrogen, and other major elements. It is the material basis of life and the most important nutrient for the human body. The main components of human cells, internal organs, muscles, and blood are proteins. Its role in the human body cannot be replaced by carbohydrates and fats. A lack of protein will seriously affect human growth and development. Human muscles and soft tissues, excluding water, are primarily composed of protein, accounting for approximately 18% of body weight. Protein also provides energy; 1 gram of protein generates 4 calories of energy. A normal adult needs 40-50 grams of protein daily from food to meet the needs of cell growth, renewal, and repair in various tissues and organs.

2. Fat

Fat is composed of carbon, hydrogen, and oxygen, with carbon and hydrogen being the predominant elements. It is distributed in the subcutaneous tissue, connective tissue between muscles, and around internal organs. Fat accounts for approximately 12% of body weight. 1 gram of fat generates approximately 9 calories of energy. Generally, foods containing protein also contain fat. Therefore, as long as there is sufficient protein in the diet, fat will not be lacking. The physiological functions of fat are mainly to provide the body with energy and store energy, while also providing the body with essential fatty acids and fat-soluble vitamins.

3. Carbohydrates

Carbohydrates, also known as sugars, are composed of carbon, hydrogen, and oxygen, and are the primary fuel for human life activities. The energy required for the body's heat production and the activities of various organ systems is mainly (approximately 70%) provided by the breakdown and oxidation of carbohydrates ingested from food (such as rice, noodles, and grains). About 80% of the food we consume daily is carbohydrates. Therefore, carbohydrates are a vital material basis for human survival and activity. One gram of carbohydrate produces approximately 4 calories of energy. The required amount of carbohydrates varies depending on the level of physical exertion. Generally, a normal adult can meet their needs by consuming 400-500 grams of staple foods daily.

4. Inorganic Salts

Inorganic salts, also known as minerals, primarily function to maintain normal physiological functions and regulate the body's acid-base balance.

(1) Calcium and Phosphorus: Calcium and phosphorus are essential building blocks for bones and teeth, and also participate in various physiological activities. The human body contains approximately 1200 grams of calcium, mainly concentrated in teeth and bones. Calcium deficiency not only affects bone and teeth growth but can also increase nerve and muscle excitability, leading to convulsions. Phosphorus plays a crucial role in the absorption of carbohydrates and fats, intermediate metabolism, and the regulation of acid-base balance in the body. Adult bones contain 600-700 grams of phosphorus. A lack of phosphorus will affect the body's normal physiological functions. Adolescents need approximately 600 mg of calcium daily, while pregnant and lactating women need 1500-2000 mg to maintain calcium turnover and dynamic balance. Calcium-rich foods generally also contain phosphorus.

(2) Iron: Iron is a raw material for the synthesis of hemoglobin in red blood cells and also participates in the transport and exchange of oxygen in the body. The adult body contains 4-5 grams of iron. Insufficient iron intake will affect hemoglobin synthesis, leading to anemia. Adolescents need 8-12 mg of iron daily, and women need 10-15 mg during pregnancy and lactation.

(3) Iodine: Iodine is a raw material for the synthesis of thyroid hormones. Thyroid hormones are important hormones that regulate metabolism in the body. Various tissues in the human body contain 20-50 mg of iodine, with the thyroid gland containing the most, about 8 mg. Iodine deficiency can cause goiter (commonly known as "big neck"). Normal adults need 100-200 micrograms of iodine daily.

5. Vitamins

Vitamins are an essential nutrient for maintaining life. They are closely related to human growth and development, metabolism, and maintaining normal physiological activities. There are many types of vitamins, among which the following are important:

(1) Vitamin A: Vitamin A plays an important role in maintaining normal vision and the normal formation of epithelial cells, and also participates in many oxidation processes in the body. (1) Vitamin A: A normal adult needs 2000-2500 IU of vitamin A daily.

(2) Vitamin B₁: Vitamin B₁ is closely related to the body's sugar metabolism and the physiological functions of the nervous, cardiac, and digestive systems. A normal adult needs 12-15 mg of vitamin B₁ daily.

(3) Vitamin B₂: Vitamin B₂ participates in oxidation and reduction reactions in the body, as well as the metabolism of sugars, fats, and proteins. A normal adult needs 1.5-2.0 mg of vitamin B₂ daily.

(4) Niacin (Vitamin PP): Niacin participates in and promotes tissue metabolism and physiological oxidation processes in the body, and has the effect of dilating blood vessels and lowering blood cholesterol. A normal adult needs 12-15 mg daily. (5) Vitamin C: Vitamin C is an important component of the intercellular matrix in the human body. It participates in redox reactions, stimulates hematopoiesis, enhances the body's resistance to infection, and has the effect of preventing scurvy. The daily requirement for a normal adult is 50-70 mg.

(6) Vitamin D: Vitamin D includes vitamins D₂ and D₃. Its main function is to promote the absorption of calcium and phosphorus in the body and maintain the balance of blood calcium and phosphorus. The daily requirement for a normal adult is 2.5 micrograms. Pregnant women, breastfeeding women, and infants have the highest requirement, about 10 micrograms per day.

Most of the above vitamins are found in various everyday foods. People with a normal, balanced diet generally do not lack them.

6. Water: Water is an important component of the human body and is an indispensable substance for all physiological activities. It accounts for about 60% of the body weight of a normal person. The younger the person, the higher the percentage of water in their body. Water plays a vital role in the transport, digestion, absorption, and excretion of metabolic waste in the body; it also participates in various physiological functions and the regulation of body temperature. A normal adult needs approximately 2500 ml of water daily (1000 ml from food, 1200 ml from drinking, and about 300 ml produced during metabolism) to maintain a balance in water intake and output, including temperature regulation. Prolonged dehydration can be life-threatening.

In addition to the six major nutrients mentioned above, dietary fiber has special benefits for the human body. It can prevent colitis and colon cancer, lower blood cholesterol levels, and prevent arteriosclerosis.