There is no published scientific evidence that CFS is caused by a nutritional deficiency. Many patients do report intolerances for certain substances that may be found in foods or over-the-counter medications, such as alcohol or the artificial sweetener aspartame. While evidence is currently lacking for nutritional defects in CFS patients, it should also be added that a balanced diet can be conducive to better health in general and would be expected to have beneficial effects in any chronic illness.