A healthy Diet/Food throughout life promotes healthy pregnancy outcomes, supports normal and healthy growth, development and ageing, helps to maintain a healthful body weight and reduces the risk of different chronic diseases leading to overall health and mental well being.
Before selecting your healthy food for your healthy life you have to know your energy and nutritional requirements and its relation with different factors . Nutritional requirements are defined as ‘ Intake of levels of nutrient that meet specified criteria of adequacy such as normal growth, prevention of deficiency signs, and maintenance of tissue pools of nutrients, and at the same time preventing the risk of deficiency or excess.
There are different factors that influence nutritional requirements of the human body. This article will help you to gain knowledge about these factors.
Requirements change with increasing age between birth and maturity. Nutrient requirements per unit body weight are higher during growth and they decrease after growth has ceased .For example the energy requirements of an infant is 103 Kcal per kg body weight , while for sedentary adult male it is only 38 Kcal per kg body weight. Similarly, the protein requirement for an infant 9-12 months is 1.5gm per kg body weight, while that of an adult is 1gm per kg body weight.
Requirement increases during pregnancy as the fourteas grows.In lactation, the requirement increases in proportion to the amount of milk secreted. At ages of 40 and beyond, there is a decline in activity , both of which results in a decline in the energy requirements. However , this is accompanied by a reduction in the nutrient requirements due to a reduced efficiency of gastrointestinal function with ageing.
There are some differences in requirements between the two sexes. However, except from, these are apparent rather than real, as the differences disappear when the requirements are expressed per unit of body weight. In the case of iron between menarche and menopause the iron requirements of females are more than that of male due to menstrual losses of blood in women.
Requirements are considered to be a function of body weight for. individuals who are not overweight. However, for some nutrients, requirements are not proportional to body weight. The general procedure for those who deviate from the normal weight is to adjust the requirements to their actual body weights. For overweight and obese individuals lean body weight may be used , instead of the total body weight. Related to the concept of requirements being a function of body weight is the concept of defining a reference man and a woman.
The reference man and woman are defined as points of reference only. For Indians, a reference man is defined as ‘a man between 20-39 years of age, with a body weight of 60 kg, free from disease and physically fit for active work. On each working day, he is engaged for 8 hours in an occupation that involves moderate activities. While not at work, he spends 4-6 hours sitting and moving about, 2 hours in active recreation and 8 hours in sleep’. A reference woman is defined as a healthy woman of 20- 39 years, with a body weight of 50 kg, engaged for 8 hours in an occupational involving moderate activities, and while not at work spends 4-6 hours sitting and moving about, 2 hours in active recreation and 8 hours in sleep.
Bioavailability of nutrients
The amount of many nutrients needed in the diet depends on the absorption or bioavailability of the nutrients. Bioavailability is defined as ‘the percent of the dietary nutrient absorbed and utilized for a specific function by the body’. The percent absorption varies widely for different nutrients depending on the quantities ingested l and the presence of other constituents of the diet. Examples are: iodine absorption is nearly 100%, calcium absorption in a normal adult is about 40% to 60% while that of iron varies from 1% to 15% , depending on the type of iron and other constituents of the diet.