The factors that affect the nutritional requirements of an individual are the quality and quantity of the food they eat, the efficiency of their digestive system in absorbing and utilizing eaten food and biochemical availability.

The quality of food that we eat can vary depending on the soil and growing conditions of that food. Soil that has been overworked and chemicals added and also drugs and antibiotics that have been given to livestock and crops to aid growth are all factors that affect nutrition in our food and can affect our own bodys biochemistry. Nutritional quality of our food can be affected by the manufacturing process, storage and preparation of our food.

The quantity of food that we eat also influences our nutritional status. In developing countries malnutrition is a huge problem but in developed countries under nutrition can occur due to dependency on heavy refined processed foods.

The efficiency of our digestive system affects our nutritional status. Bad condition of our intestines will reduce the absorption of digested foods into our blood stream. Metabolic faults, sensitivity to certain food and the presence of substances like tea and coffee can affect the absorption rate of certain nutrients.

Biochemical availability is the optimum range of intake of a person essential nutritional requirement. This nutritional requirement is influenced by age, growth, sex, pregnancy and breastfeeding, illness, psychological and emotional stress, activity level and other factors like smoking and drinking.

Nutritional requirements change as a person gets older, because the elderly use a lot of medication their absorption, excretion and utilization of nutrients can be affected. Growing children have different nutritional needs to that of adults. For example, a growing infant requires a higher intake of essential fatty acids than that of an adult. In the same way there are different nutrition requirements for young and old there are also very different requirements between the sexes. For example, a womans nutritional requirements can vary throughout her menstrual cycle, also a woman who is pregnant or breastfeeding has different nutritional requirement to that of one who is not. Nutritional requirement vary depending on whether someone is healthy or ill. As diseases are unique so are the nutritional requirements needed whilst that person is ill. The same applies to psychological and emotional stress. When people are affected by stress their appetite is affected, this results in less intake of food which in turn results in less nutrients being absorbed.

A person activity level will affect their nutritional requirement. An athlete will need a different nutritional requirement to that of an office worker. Exercise improves metabolic efficiency in some people and increases nutrient requirement.

People may find that certain nutritional requirements are increase within their family. Genetics can play a part in an extra need for certain nutrients. Other factors such as using recreational drugs, smoking and drinking can affect nutrient requirements. Even beverages like Tea and Coffee can affect nutrient requirements; they both inhibit the absorption of Iron and Zinc.