The diet is the source of some 40 nutrients for human beings. These classically are divided into energy-yielding dietary components (carbohydrates, fats, and proteins), sources of essential and nonessential amino acids (proteins), essential unsaturated fatty acids (fats), minerals (including trace minerals), and vitamins (water-soluble and fat-soluble organic compounds) (see Shils et al . , 1999). | Early signs and symptoms of chronic retinoid intoxication include dry and pruritic skin, skin disquamation, erythematous dermatitis, disturbed hair growth, fissures of the lips, pain and tenderness of bones, hyperostosis, headache, papilledema, anorexia, edema, fatigue, irritability, and hemorrhage. Intracranial pressure may be increased, and neurological symptoms may mimic those of a brain tumor (pseudotumor cerebri). In infants, increased intracranial pressure, a bulging fontanel, and vomiting are seen early. In addition to hepatosplenomegaly, pathological changes in the liver include hypertrophy of fat-storing cells, fibrosis, sclerosis of central veins, and cirrhosis, with resultant portal hypertension and ascites. The activity of alkaline phosphatase in plasma rises because of the increased osteoblastic activity; a number of cases of hypercalcemia have been reported in children. Elevations in plasma triglycerides and reductions in the cholesterol of high-density lipoprotein also are observed.
