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Food Constituents

Food is vital for optimal health and wellbeing. This video outlines the role of macronutrients and micronutrients in the diet.

Food is vital for optimal health and wellbeing. The human body requires adequate amounts of macronutrients and micronutrients for energy, growth and maintenance.

What are macronutrients?

Macronutrients are the nutrients we need in larger quantities for energy and tissue maintenance. They include carbohydrates, fats and proteins. Fiber is also considered a macronutrient, although it is not a true nutrient, because it passes the gastrointestinal tract unabsorbed, and it is directly excreted.

  • Carbohydrates: Carbohydrates are a group of important nutrients in the diet as a source of energy. 1g provides about 4 Kcal to the body. They contain the elements carbon, hydrogen and oxygen and are produced in plants by the process of photosynthesis. Carbodhyrate intake comes mainly from vegetable sources.
  • Lipids: Fats and oils, also known as lipids, are broken down in the body by a process of oxidation to release energy. Fat is a more concentrated source of energy than carbohydrates. 1g of fat contains 9kcal. Dietary fats are classified into fats and oils based on their fatty acid compsition.
  • Proteins: Protein is a key component of the structure of the body necessary for growth and maintenance. Although not its primary role, protein can serve as a source of energy when insufficient carbohydrate and fats are available to meet the bodies needs. Dietary proteins are present in animals and plants products such as meat, fish, eggs, bread, nuts and vegetables.

What are micronutrients?

Micronutrients are mostly vitamins and minerals, and are equally important as macronutrients but consumed in very small amounts. They are essential nutrients, because the body can’t make them or can’t make them in sufficient quantity, and thus, they must come from the diet.
  • Vitamins
Vitamins are complex organic substances that are needed in very small amounts for many of the essential processes carried out in the body. Some are involved as co-factors in metabolic reactions; some are antioxidants and one is a pro-hormone. Vitamins have been traditionally grouped into two categories: the fat soluble and water soluble vitamins. Fat soluble vitamins include: Vitamin A, Vitamin D, Vitamin E and Vitamin K. Water soluble vitamins include the Vitamin B complex and Vitamin C.
  • Minerals
Minerals are inorganic substances required by the body for a variety of functions. This includes: the formation of bones and teeth; as essential constituents of body fluids and tissues; components of enzyme systems; and nerve function. Some minerals are needed in large amounts, grams per day, (e.g. Calcium, Magnesium, Phophorus, Potassium, Sodium and Chloride), whilst others are needed in smaller amounts, micrograms per day, also known as trace minerals (e.g. Flourine, Iodine, Iron, Selenium Zinc and Copper).

Micronutrients are present in natural foods, but it is more difficult to find them all simultaneously in the same food. Eating a varied diet will help ensure an adequate supply of most micronutrients for healthy people.

What we would like you to do

Please share your thoughts in the comments section below:

  • Do you think you eat enough macronutrients and micronutrients? Why / Why not?
  • Do you think you could improve your diet? If so, what would help you improve it?
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Introduction to Food Science

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FutureLearn - Learning For Life

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