Intro to Nutrition - Macronutrients

The chemical elements humans consume in the largest quantities are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Macronutrients are mainly made of these chemical elements.

There are 3 primary macronutrients defined as being the classes of chemical compounds humans consume in the largest quantities and which provide bulk energy. These are protein, fat, and carbohydrate.

Water and the macrominerals calcium, salt (sodium and chloride), magnesium, and potassium (along with phosphorus) have we added to the list of macronutrients because they are required in large quantities compared to other minerals.

The big 4

Proteins are organic compounds that consists of the amino acids joined by peptide bonds. The body cannot manufacture some of the amino acids (termed essential amino acids); the diet must supply these. In nutrition, proteins are broken down through digestion by proteases back into free amino acids.

Carbohydrates are compounds made up of sugars. Carbohydrates are classified by their number of sugar units: monosaccharides (such as glucose and fructose), disaccharides (such as sucrose and lactose), oligosaccharides, and polysaccharides (such as starch, glycogen, and cellulose).

Fats consist of a glycerin molecule with three fatty acids attached. Fatty acids are unbranched hydrocarbon chains, connected by single bonds alone (saturated fatty acids) or by both double and single bonds (unsaturated fatty acids). Fats are needed to keep cell membranes functioning properly, to insulate body organs against shock, to keep body temperature stable, and to maintain healthy skin and hair. The body does not manufacture certain fatty acids (termed essential fatty acids) and the diet must supply these.

Water is an essential macronutrient necessary for energy production. Essential to the survival of all organisms, water composes approximately 70% of the human body by mass. It is a crucial component of metabolic processes and serves as a solvent for many bodily solutes. Humans can survive for several weeks without food, but for only a few days without water. The exact amount of water a human needs is highly individual, as it depends on the condition of the subject, the amount of physical exercise, and on the environmental temperature and humidity. In the US, the reference daily intake (RDI) for water is 3.7 litres per day for human males older than 18, and 2.7 litres for human females older than 18 including water contained in food, beverages, and drinking water.

Macrominerals:

1. Calcium is the most abundant mineral in the body and is required for muscle contraction, blood vessel expansion and contraction, secretion of hormones and enzymes, and transmitting impulses throughout the nervous system.

2. Sodium is an essential element for all animal life and for some plant species. In animals, sodium ions are used in opposition to potassium ions, to allow the organism to build up an electrostatic charge on cell membranes, and thus allow transmission of nerve impulses. Salt is a dietary mineral composed primarily of sodium chloride.

3. Chloride is a chemical the human body needs for metabolism (the process of turning food into energy). It also helps keep the body's acid-base balance. The amount of chloride in the blood is carefully controlled by the kidneys.

4. Magnesium is the fourth most abundant mineral in the body and is essential to good health. It is needed for more than 300 biochemical reactions in the body.

5. Phosphorus is a key element in all known forms of life. Living cells use phosphate to transport cellular energy in the form of adenosine triphosphate (ATP). Nearly every cellular process that uses energy obtains it in the form of ATP.

6. Potassium ion is a nutrient necessary for human life and health, specially because in animal cells, potassium ions are vital to keeping cells alive. Potassium assists in protein synthesis from amino acids and in carbohydrate metabolism.

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Other articles in this series:

- Mixing Macronutrients
- Fatty acids: A revolution