The nutritional content in foods is measured in terms of its nutrient composition. Nutrients are substances that add to or take away from a person's health. There are various substances that contribute to the nutritional quality of foods. Examples of these substances are vitamins, minerals, proteins, carbohydrates, fats, vitamins and hormones. The foods that contain all these substances together are called complete foods.
There are several organizations that define nutrition. The National Academy of Sciences is one such institution. It defines nutrition based on biological, ecological and environmental factors. The values it assigns to the different subjects of nutrition are referred to as nutrient criteria. These criteria determine what nutritional products a person can include in his diet.
The dietary guidelines of the National Academy of Sciences (NAS) define nutrition for individuals. These dietary guidelines are to be followed strictly for good health. They are also used to set down the level of calorie intake required by an individual for maintaining good health. The dietary guidelines help to control weight, regulate carbohydrate and fatty food consumption, set down the amount of protein, determine the amount of sodium and reduce caloric intake.
A wide number of books have been published to define nutrition. Dr. Evelyn Dew, a professor at Texas Woman's University, has written a number of books on this subject. Mary Scholes has written a very popular book entitled Foods That Define Nutrition. Dr. David Griswold and his wife Edy the mother of six have published a book entitled Essential Foods. The Fomonte School of Medicine at the University of Minnesota has published Nutrition and Your Children. In these books we find that nutritionists everywhere have developed their own lists of terms and concepts used to describe the nutrients and food groups.
The NAS definition of nutrition is a way of communicating the importance of various nutrient groups to our diet. The nutritional status of an individual is determined by his diet. Nutrient classification is usually done on the basis of the proportions present in foods. Foods that are rich in certain nutrients are classed as such. Other foods that are rich in some nutrients but lack in other essential nutrients are classed as poor in nutrients. Often an average dietary pattern may not adequately represent the nutritional status of an individual.
One may classify food as good or bad depending on its level of nutrient content. A diet should contain a balance of all the basic food groups, but a poor nutritional status will suggest foods with a very low nutritional value and those with a high level of nutrient richness. Good nutrition should provide a variety of foods in an equal proportion. It is also important to ensure that a person gets enough calories so that he/she is neither underweight or overweight.
The dietary requirements of individuals vary and they depend on their gender, age and even body size. There is no universal dietary requirement since everyone is different. Food habits are a major factor in shaping an individual's nutrition and they have a major impact on nutrient intake. Food habits can be changed by making changes in the diet. Changing the diet drastically can result in rapid weight loss, but it can also have serious side effects like dehydration and even organ failure. Individuals who are overweight should consult a dietician to help them design a good diet plan and ensure that they get all the nutrients they need.