Nutritional diseases refer to those conditions that are caused by consistently having either too little or too much food. Lack of certain food constituents, such as vitamins and minerals, could lead to what are known as deficiency diseases. Excess of these, on the other hand, could cause certain disorders. A third possible cause of nutritional diseases refers to a group of inherited metabolic disorders. Inborn errors in carbohydrate, protein, pigment, and fat metabolism are the respective causes of four nutritional diseases listed below.
1. Galactosemia – Disorders in carbohydrate metabolism cause galactosemia. In this nutritional disease, the body is unable to convert a particular form of carbohydrate (galactose) into another form (glucose) because the enzyme necessary for such conversion is not present. An infant with galactosemia seems normal at birth. A few days later though, the infant develops difficulty in feeding.
Left untreated, the disease could lead to failure in growth resulting from malnutrition; worse, it could lead to death. Treating an infant with galactosemia calls for the exclusion (from the diet) of foods that contain galactose, including milk and all milk products. The pediatrician will program a diet that will provide the infant all the nutrients essential for normal growth.
2. Phenylketonuria (PKU) – Disorders in protein metabolism cause this nutritional disease. In this condition, tyrosine – a non-essential amino acid – is not properly synthesized within the body due to the lack or absence of an enzyme. Consequently, phenylalanine (an indispensable amino acid that is the precursor of tyrosine) gathers up within the fluids and tissues of the body and flows over into the urine.
A serious complication of phenylketonuria is mental retardation. Treatment of the disease involves programming a diet containing a minimum of phenylalanine, which, by the way, is naturally found in breast milk. An infant with this condition most definitely needs to be under the care of a physician.
3. Porphyria – Disorders in pigment metabolism are the causes of porphyria. In this disease, the body uses porphyrin (the pigment in red blood cells) to help build its hemoglobin and other pigments. One type of porphyria, called cutaneous porphyria, is known to cause sensitivity of the skin to sunlight, with abnormal pigmentation and skin lesions.
In another type of the disease, known as acute porphyria, there is constipation, abdominal pain, and vomiting. Muscle weakness, seizures and mental disturbances may also occur here. Acute attacks are usually brought on by some infections. Treatment requires protecting the skin from sunlight.
4. Xanthomatosis – Disorders in fat (lipid) metabolism cause xanthomatosis, which is also referred to as hypercholesteremia. In this condition, the amount of cholesterol is increased more than the other lipids that normally occur in the body (in the blood serum, it is at least two times normal). Cells laden with cholesterol accumulate, causing swellings in the skin, certain tendons, and in the heart.
Two conditions – coronary artery disease and arteriosclerosis – frequently occur with xanthomatosis. Lowering the cholesterol in the blood serum is the most important part of treatment. The patient’s diet should exclude foods that are rich in saturated fatty acids. These include eggs, dairy products, and meat.
There certainly is much variation in the relative importance of environment and heredity with respect to disease. But in all the nutritional diseases mentioned above, the influence of heredity is obviously the main factor.
1. “Galactosemia,” on Genetics Home Reference – http://ghr.nlm.nih.gov/condition=galactosemia
2. “Phenylketonuria (PKU)” – http://www.medhelp.org/lib/pku.htm
3. “Porphyria” – http://www.wrongdiagnosis.com/p/porphyria/intro.htm
4. “Xanthomatosis” – http://www.wrongdiagnosis.com/medical/xanthomatosis.htm