In the undeveloped world controlling life-threatening infective diseases helps to limit the impact of nutritional deficiency. Malaria, measles, HIV, diarrhoea and parasitic infestations are the problems most likely to cause, or be associated with, nutritional deficiencies and the presence of nutritional deficiencies usually greatly increases the mortality from these illnesses.
In the UK the situations that result in serious nutritional deficiencies are mainly due to:
In the UK identifying and treating chronic health problems is particularly important in the treatment of individuals with severe deficiencies and is less relevant when addressing public health nutritional problems.
Many common health problems in adult life have nutritional consequences increasing the risk of deficiency and sometimes nutrient toxicity.
Many such patients receiving medical care have already had a nutritional assessment as part of their standard care but some may not or their nutritional status may change as they get older or their disease progresses. This may alter their need for dietary advice and possibly the use of nutritional supplements. Many such individuals may be self-treating with nutritional supplements bought over the counter and the advisability of this may be in question.
In the UK the National Institute for Health and Clinical Excellence, NICE, places considerable emphasis on screening patients at risk of nutritional deficiency on the basis of being underweight or losing weight unintentionally [link]. This simple tool and related advice will often help to identify disease-induced nutritional deficiencies, which are more prevalent than many doctors have previously thought.
Chronic health problems cause nutritional deficiencies by leading to a state of negative balance of one or more essential nutrients through one of five means:
This latter category includes situations of alcohol excess, the effect of disease on nutrient metabolism, drug-induced nutritional deficiencies and genetic alterations in the metabolism of the nutrient.
For many people in developed countries a lack of physical exercise is also a factor as it results in a lower requirement for energy and thus a lower intake of many essential nutrients as well as reduced bone and muscle formation in children and young adults.