What are Nutrients?

These are the organic compounds present in the food that provide nourishment essential for the development and growth of our body. Nutrients not only provide us with the required energy to carry out various biological processes but are also the building blocks for repair and growth in our bodies.

Types of Nutrients

Generally, nutrients are divided into two main categories.

• Macronutrients: These are required by the body in large amounts. Example- fats, proteins, carbohydrates.
• Micronutrients: These are required by the body in a small amount. Example - calcium, vitamins, iron

According to the essentiality, there are three types of nutrients.

• Essential nutrients
• Conditionally essential nutrients
• Non-essential nutrients

Essential Nutrients

These nutrients can not be synthesized by the body; therefore, they have to be taken externally through food. They have a vital role in disease prevention, growth, and good health.

There are six types of essential micronutrients and macronutrients.

Proteins

Proteins are the macronutrient that consists of complex and large molecules. Every cell in our body requires proteins to function properly. All proteins are made up of smaller units known as amino acids. There are only 20 amino acids that combine in different ways to form thousands of protein molecules. Nine out of 20 of them cannot be synthesized by humans. They are called essential amino acids. These are valine, threonine, lysine, leucine, methionine, tryptophan, histidine, phenylalanine, and isoleucine. It is the sequence of amino acids in a protein molecule that determines its structure and unique function. The main functions of proteins are- making antibodies, hormones, enzymes, essential substances; performing the development of bones, hair, skin, muscle; maintaining fluid balance, immune system responses, vision, etc. Some good sources of protein-based foods are- beans, legumes, poultry, red meats, fish, seafood, eggs, dairy products, soybean, nuts, quinoa, etc. Though meat and fish contain the highest number of proteins, vegetarians consume proteins from plant-based products.

Carbohydrates

Carbohydrates are the starch and sugar compounds that give energy to the cells. During digestion, the complex carbohydrates break down into simple glucose molecules. It is this glucose molecule, which each cell uses to obtain energy and perform various functions. There are three main groups of carbohydrates: Monosaccharides, the most basic form of carbohydrate. Example- glucose and fructose. Disaccharides, when two monosaccharide molecules are bonded together. Examples -lactose and sucrose. Polysaccharides, when more than two monosaccharide molecules are bonded together. Examples- starch and fiber. Simple carbohydrates are the type of sugar made from monosaccharides and disaccharides, whereas complex carbohydrates are the type of sugar made from polysaccharides. Foods with complex carbohydrates are more nutrient-rich than simple carbohydrates.

Fats

Fatty acids are the building blocks of fats in our bodies. Healthy fats are important nutrients for our bodies as they help in the absorption of some fat-soluble vitamins such as Vitamins A, D, E, and K.  Fats are high in calories and are rich sources of energy. There are generally three types of fats: saturated fat has single bonds between its carbon molecules. Molecules of unsaturated fat have one or more double or triple bonds. Unsaturated fats are further divided into monounsaturated and polyunsaturated fats. Saturated fats are solid at room temperature, but unsaturated fats are liquid at room temperature. Well-known unsaturated fats are omega-6, omega-3, omega-3s fatty acids, and alpha-linolenic acids. Trans-fat is a type of fat that is produced via cooking techniques. It is a very harmful fat for the body.

Minerals

Minerals are naturally occurring solid substances made up of one or more elements. Some minerals are important for the proper functioning of our body. These are micronutrients. According to their needs in the human body, they can be divided into two types - major minerals and trace minerals.

Major minerals are those that our body needs in large quantities. Some examples are calcium, magnesium, potassium, sulfur, chloride, phosphorous, and sodium. The function of calcium is to strengthen bones; the functions of magnesium and potassium are to maintain nerve and muscle cells; sulfur helps to make DNA (deoxyribonucleic acid); chloride helps in fluid balance; phosphorous helps in the formation of teeth.

Trace minerals are those that our body needs in small quantities. Examples of trace minerals are iron, fluoride, molybdenum, zinc, manganese, and selenium. Food sources, which contain high levels of minerals are - whole grains, seafood, salt, red meats, milk and dairy products, vegetables, etc.

Vitamins

It is a kind of organic essential nutrient that we need for growth, development, and metabolism. Depending on the solubility, it is divided into two types - water-soluble vitamins and fat-soluble vitamins. Among the 13 essential vitamins, four are soluble in fat and the remaining nine are soluble in water. Fat-soluble vitamins are Vitamin A, Vitamin D, Vitamin K, and Vitamin E. Water-soluble vitamins are Vitamin B complex; Vitamin B-1 or thiamine, Vitamin B-2 or riboflavin, Vitamin B-3 or niacin, Vitamin B-5 or pantothenic acid, Vitamin B-6 or pyridoxine, Vitamin B-7 or biotin, Vitamin B-9 or folate or folic acid, Vitamin B-12 or cyanocobalamin), and vitamin C or ascorbic acid. Each vitamin is important for the body. Though required in a very small amount, deficiency of any vitamin may lead to serious health problems. A balanced diet is the best way to obtain each type of vitamin.

Water

Water is a tasteless, odorless, colorless, transparent, inorganic, chemical substance. It is the most important essential nutrient of the human body. It plays a significant role in almost all the physiological functions of our body. The major functions of water are to maintain proper blood circulation, deliver oxygen to every cell, and dissolve minerals and nutrients. In addition, water plays an important role in kidney and liver protection, constipation, lubrication, and skincare. The only way to keep the body hydrated is to drink plenty of water. Fruit also contains a lot of water.

Conditionally essential nutrients

Under certain conditions, certain organic molecules can be synthesized in sufficient quantities by an organism. Examples of conditionally essential nutrients are arginine, inositol, glutamine, nucleotide, and taurine.

Non-essential nutrients

Non-essential nutrients are those nutrients that are made by the organism itself or are found in sufficient quantities in all the foods they eat. This type of nutrient is usually obtained from two types of fiber- soluble dietary fiber and insoluble dietary fiber. Bacteria, which are present in our large intestine, can metabolize soluble fiber. These soluble fibers serve a prebiotic function and form short-chain fatty acids. Insoluble fibers are not metabolized in the human digestive tract. They maintain our bowel movements to avoid constipation.

Intake capacity and disease management

Dietary Guidelines for Americans 2015–2020 stated that an adult female needs 46g of proteins daily and an adult male needs 56g. Sufficient protein intake can reduce malnutrition, hormone imbalance, advanced stages of cancer, eating disorders, etc.

• Carbohydrates reduce the risk of type 2 diabetes and cardiovascular disease. According to dietary guidelines for Americans, healthy individuals consume 45-65% of their daily calories from complex carbohydrates.
• Good fat helps in cell growth, blood clotting, new cell formation, muscle movement, hormone balancing, brain functioning, and immune functioning. It also reduces the risk of heart disease and type 2 diabetes. According to recent Dietary Guidelines for Americans, a person should consume 20–35% of their kilocalorie from healthful fats.
• Trace minerals like chromium, copper, iodine, iron, etc. help in strengthening bones, prevention of tooth decay, aid in blood clotting, help to carry oxygen, support the immune system and support healthy blood pressure.
• Vitamin A helps in normal vision. Vitamin C is known as ascorbic acid and helps in growth development and tissue repair. Vitamin D helps in bones, teeth, and muscle health. A person gets the most vitamins from fruits and green vegetables.
• An average of 3.7 liters for men and 2.7 liters for women should drink water every day. Although it depends on pregnancy status, climate, or physical activities.

Conclusion

We always thought fats and carbs are harmful to our bodies. But if we maintain low-fat low-carb and avoid hydrogenated oil, then it keeps our body healthy. Even in this Covid-19 situation, we need a nutrient-dense food habit. We have to maintain the perfect amount of essential nutrients according to our body needs and green vegetables, fruits, poultry, and fish are good sources of nutrients. Except that we have to take the perfect amount of water to hydrate our body.

Context and Application

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for

• Bachelor of Science (Nutrition & Dietetics)
• Masters in Nutrition & Dietetics

Practice Problems

Q 1. Which of the following is a trace mineral?

1. Chromium
2. Vitamin A
3. Palm oil
4. Seafood

Answer- (a)

Explanation-Trace minerals are those minerals that our body needs in very small amounts. Vitamin A is a source of vitamins, seafood is a source of protein,  and palm oil is a source of fat. 

Q 2. What is the chemical name of Vitamin C?

1. Salicylic acid
2. Ascorbic acid
3. Malic acid
4. Carboxylic acid

Answer- a

Explanation- Vitamin C is another name for ascorbic acid. 

Q 3. Which of the following is a water-soluble vitamin?

1. Vitamin K
2. Vitamin B-2
3. Vitamin E
4. Vitamin D

Answer- b

Explanation- All the above vitamins are soluble in fats except vitamin B-2. 

Q 4. Which of the following is a fat-soluble vitamin?

1. Vitamin A
2. Vitamin C
3. Vitamin B-6
4. Vitamin B-12

Answer- a

Explanation- All the above vitamins are soluble in water except Vitamin A. 

Q 5. Which of the following is a source of trans fats?

1. Quinoa
2. Strawberry
3. Frozen pizzas
4. Yogurt

Answer- c

Explanation- Quinoa is a protein-rich food. Strawberries are a good source of vitamin C. Yogurt is high in protein, and trans fats can be found in frozen pizzas.

Related Concepts

• Nutrition Cycle
• Nutrition 
• Food Composition