nutrition
Meaning of nutrition: The chain runs from appetite through digestion to absorption, and illness can break it at any single point along the way.
Definition of nutrition
Nutrition is the process by which the body takes in food and uses it for energy, growth and repair. It begins with eating, continues as the digestive system breaks food down into nutrients, and ends as those nutrients are absorbed and delivered to tissues. The word also names the study of that process and the assessment of a person's nutritional state.
How do macronutrients and micronutrients differ?
| Macronutrients | Micronutrients | |
|---|---|---|
| What they are | Carbohydrate, protein and fat | Vitamins and minerals |
| Amount required | Grams each day | Milligrams or micrograms each day |
| Main contribution | Energy, plus raw material for building tissue | Enabling chemical reactions; no meaningful energy |
| Effect of a shortage | Weight loss, muscle wasting, slow healing | Specific deficiency states, such as anemia or weakened bone |
Protein does double duty, supplying energy while also providing the amino acids from which muscle, enzymes and antibodies are assembled. Water and dietary fiber sit outside both groups: neither supplies energy, yet the process cannot run properly without them.
Where can the process break down?
Nutrition is a chain, and illness can break any link in it. Appetite may fall, whether from the illness itself, from pain, from low mood, or as an effect of treatment. Swallowing may become difficult or unsafe. The digestive system may fail to break food down, or the intestinal lining may fail to take up what has been broken down. Requirements may rise sharply, as they do during infection, after burns, or in recovery from major surgery, so an intake that was previously sufficient no longer is. Losses may increase through vomiting, diarrhea or a draining wound. These mechanisms are distinct, which is why the same observation of weight loss can have several quite different explanations behind it.
How is intake supported when eating is not enough?
Enteral nutrition delivers a liquid feed into a working digestive tract, usually through a tube passed into the stomach or small intestine, and it keeps the gut lining in use. Parenteral nutrition bypasses the digestive tract altogether, delivering nutrients directly into a vein, and is used when the gut cannot absorb or has to be rested. Nutritional status itself is judged from the trend in weight, muscle bulk, an intake history, physical signs and laboratory measures. It is tracked routinely in serious and long-lasting illness because it bears on healing, on infection risk, and on how well treatment is tolerated.
Used in a sentence
A dietitian evaluated the patient's nutritional status given the recent unintentional weight loss.
Good to know
Macronutrients supply the body's energy needs, while micronutrients support other essential processes without contributing meaningful calories, a distinction used whenever a person's diet or nutritional status is assessed.
Word origin
Where “nutrition” comes from
From Latin nutrire, meaning to nourish.