Nutrition

Nutrition is a process in which organisms gain energy from food to perform certain metabolic activities of the body to survive.

Nutrients are the substances which provide energy and biomolecules necessary for carrying out the various body functions. All living organisms need nutrients for growth and proper functioning. Some animals feed on simple inorganic compounds to meet their nutrient requirement, while others utilise complex compounds. The mode of nutrition varies from one species to another.

Modes of Nutrition:
Based on the way used to acquire food, nutrition can be classified into two types:

1. Autotrophic nutrition: This is a mode of nutrition in which the organism synthesise their own food.
It is of two (2) types:
i. Photoautotrophic- In this type, organisms use simple inorganic matters like water and carbon dioxide in the presence of sunlight and chlorophyll to synthesize food on their own. Example: Green plants, and algae such as Cyanobacteria.
ii. Chemoautotrophic: In this type, the organisms use chemicals as the source of energy to synthesise food. Examples: Nitrobacter and Sulphur bacteria.


2. Heterotrophic nutrition: This is the mode of nutrition in which the organisms cannot synthesise their own food and depend on other organisms for already

It is of three (3) types:
i. Holozoic nutrition: This animal-like nutrition. In this type, the organisms engulf the food by eating plants or animals.

These can be of various types

a. Herbivorous- The organisms that feed only on plants. Example: Goat
b. Carnivorous- Organisms that feed only on animals. Example: Lion
c. Omnivorous- The organisms that feed on both plants and animals. Example: Humans
d. Sanguivorous- The organism that feeds on blood. Example: Leech
ii. Saprophytic nutrition: These organisms feed on the dead and decaying matter of dead organisms. These are known as decomposers as help to decompose the dead matter. Example: Bacteria, Mushroom and Earthworm.
iii. Symbiotic nutrition: These organisms live with other organisms in close association and obtain nutrition with them.

a. Parasitism- In this type, an organism depends on the other organisms known as host organism completely. These obtain nutrition from the host organism. Example: plasmodium and leech. Plasmodium is an endoparasite as it lives inside the host such as female anopheles. Leech is ectoparasite as it lives outside the host body.
b. Mutualism- In this type, both the organisms living in close association are helpful for each other. Example: Rhizobium living in the roots of the plants. The Rhizobium obtains nutrition from the plants and helps the plant by fixing nitrogen from the air and providing it to the plants.
c. Commensalism- In this type, one organism gets the advantage while the other neither derive benefit or harmed. Example: A golden jackal following a tiger to feed on leftovers from its kills.

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Malnutrition also called malnourishment is a condition resulting from eating a diet that contains either insufficient or too much of nutrients as a result of which health problems ensue. It is an inadequate or excess intake of protein, energy and micronutrients such as vitamins, and the frequent infections and disorders that result. The nutrients involved are calories, carbohydrates, vitamins, proteins or minerals. Undernutrition during pregnancy, or before two years of age may cause permanent mental and physical development problems.

Malnutrition is consequently the most important risk factor for the burden of disease in developing countries.

Malnutrition – Types

Malnutrition covers 2 different categories of conditions that are given below

  1. Undernutrition – This category covers stunting (low height for age), wasting (low weight for height), underweight (low weight for age) and micronutrient deficiencies (lack of important minerals)

  2. Others – This category consists of overweight, obesity, diet-related non-communicable diseases (such as heart disease, stroke, diabetes, and cancer).

Effects of Malnutrition

  1. Obesity

  2. Coronary heart disease

  3. Starvation

  4. Childhood protein-energy malnutrition (Kwashiorkor)

  5. Vitamin, mineral and fiber deficiency diseases

  6. longer healing time for wounds

Some deficiencies can trigger specific health problems. For example:

Lack of vitamin A

Around the world, many children develop vision problems due to a lack of vitamin A.

Lack of vitamin C

A lack of vitamin C can result in scurvy.

Scurvy is rare in the United States (U.S.), but it can develop if a person does not have a varied diet with plenty of fruits and vegetables. Fresh, frozen, and canned fruits and vegetables all contain vitamin C.

People who are particularly at risk of scurvy include:

  • older adults

  • young children

  • those who consume a lot of alcohol

  • some people with certain mental health conditions

An overall deficiency

Malnutrition can lead to marasmus, which is a severe form of malnutrition. Marasmus is a deficiency of protein and overall energy intake.

A person with marasmus will have very little muscle or fat on their body.

Over-nutrition

Over-nutrition is another type of malnutrition. It occurs when a person takes in more nutrients than they need. The result may be an accumulation of body fat from the excess nutrients, resulting in overweight or obesity.

Over-nutrition has several health implications. People who have overweight or obesity are at greater risk of:

  • heart disease

  • high blood pressure

  • diabetes

  • cancer

  • high cholesterol

The rate of over-nutrition is growing worldwide. The World Health Organization (WHO) reports that in 2020, 5.7% of children under 5 were overweight, an increase from 5.4% in 2000.