A balanced diet is the one that consists of proper quantities and proportions of foods needed to maintain health or growth. It provides, in proper proportions, the human body with all the nutrients necessary for adequate nutrition. Such a diet contains proper proportions of carbohydrates, fats, proteins, vitamins, minerals and water; ingredients necessary to maintain good health.
A balanced diet is food intake that includes all of the dietary needs of the organism in the correct proportions.
Proteins are also used as an ‘emergency’ energy source, if the diet has insufficient carbohydrates and fats in it.
A balanced diet will also include nutrients that do not provide energy, such as:
- minerals like iron, to make haemoglobin
- vitamins, such as vitamin C, which prevents a disease called scurvy
- fibre, which prevents constipation
Included Food Groups
Vitamins are specific chemicals needed by the body in relatively small amounts. Collectively they fulfil a wide range of functions including enabling the body to make efficient use of other parts of a balanced diet, e.g. vitamin D facilitates absorption of calcium and phosphorous. Although all vitamins are organic compounds, they have no common chemical structure or functions.
There are two important groups, or types, of vitamins:
- Water-soluble vitamins e.g. C and the B found in many fruits and vegetables
- Fat-soluble vitamins e.g. A, D and E found in fatty foods e.g. many dairy products
Carbohydrates are broken down by the digestive system into energy in the form of glucose which can be absorbed into the blood. The body needs and uses energy for the following:
- Active transport
- Synthesis of biochemical macromolecules
- Cell division
- Muscle contraction
Often called “building blocks,” proteins are essential for growth (especially in the case of infants, children and body-builders) and for maintenance and repair of body tissues. After processing via the digestive system, the proteins components are used in body tissues.
Proteins are broken down by the digestive system into amino acids. There are different types of proteins found in a wide range of animal and non-animal food sources e.g. meat, fish, eggs, pulses and beans. A balanced diet includes all of the essential amino acids, which are so called because they are needed but cannot be synthesized by the human body.
Some fats (also known as “lipids”) are essential for a healthy balanced diet. They are broken down by the digestive system into fatty acids and glycerol. These compounds are then used in cell membranes and as parts to form steroid hormones.
In terms of their chemistry, lipids are highly reduced organic compounds, hence they can be oxidized to release energy.
There are many different fat molecules but, in general, fats can be divided into two main groups:
- Saturated fats and cholesterol¾typically derived from animal products such as meats
- Unsaturated fats¾typically from plant sources such as soya
Dietary Fibre, or roughage, consists mainly of cellulose from plant cell walls and is part of many plant-based food sources, including fresh fruits and vegetables and whole grains and pulses. The main functions of dietary fibre concern the health of the large intestine, including helping to form soft bulky faeces, thereby easing defecation and reducing the probability of constipation.
Water is an essential part of the human diet. It is necessary for the body in which it is used as a solvent, a transport medium, a substrate in hydrolytic reactions and for lubrication. Although humans need water every day, it is not necessarily consumed in the form of drinking water itself but as the major part of many drinks and some liquid or partially foods such as soups, sauces, dressings and ice-desserts.
Unlike vitamins, minerals are chemical elements. There are two important groups, or types, of minerals:
- Macro minerals—found in typical adult human bodies in quantities > 5g ; > 100mg needed daily
- Micro minerals—found in typical adult human bodies in quantities < 5g ; 1-100mg needed daily
Minerals help maintain ideal concentrations of tiny amounts of chemicals (called solutes) dissolved in the water present in the tissues of the body so that the solution moves around and through the body’s tissues in the most beneficial way for the overall health of the organism.
Minerals are usually ingested as part of some of the main food types, e.g. calcium (Ca) in dairy foods, and iron (Fe) in red meats.
Adequate Diet vs. Balanced Diet
An “adequate diet” includes sufficient energy for the person’s needs¾though the energy in the diet may be in any form, e.g. as carbohydrate, protein, fat, etc.
A “balanced diet” not only includes sufficient energy for the person’s needs but all of the person’s dietary requirements in the correct proportions.