Phosphorus magnetic resonance spectroscopy in nutritional research.

In conclusion, muscle and liver 31P MRS can be used to assess energy state in various nutritional conditions and to follow different metabolic changes induced by modification of substrate availability. 31P MRS studies of humans and animals suggest that fasting and low caloric intake reduce the oxidative metabolism "efficiency" of muscle during exercise and produce a better bioenergetic state at rest. Liver studies during fasting also indicate a lower energy state. Acute supplements of substrate to working muscle that is affected by a metabolic disease can improve its energy metabolism as observed by 31P MRS. Modification of diets in patients with a metabolic disease can also be followed by this technique, thereby aiding the clinical evaluation of therapies. The acute and chronic effects of alcohol, which reduce the energy metabolism of liver, are another example of nutritional problems studied by 31P MRS both in humans and animal models. A valuable aid in nutritional research, especially in humans, 31P MRS is noninvasive and can be repeated without harmful effects.