Lipid Disorders

Lipids are required in the body for different structural and functional activities. A dietary lipid deficiency may alterlaffect these functions to varying extent.

Hypovitaminosis

Lipids are essential for the absorption of fat-soluble vitamins, which may get affected in absence of sufficient fat. 

Ketosis

A special condition occurs in the body when the liver catabolizes excessive amounts of fatty acids in the absence or scarcity of carbohydrates. This condition is called "ketosis" and is observed:

• When glycogen stores are depleted, stored body fats becomes the chief energy source as in case of starvation
• When high fat and low carbohydrate diet is consumed
• In untreated diabetes mellitus.

In ketosis, liver gets flooded with fatty acids coming from diet or stored fat and produces compounds called ketones. These compounds cannot be oxidized by the liver and are then put in the blood. As the blood ketone levels go up, they are excreted in the urine. This statelcondition is called ketonuria. The symptoms of ketosis include greater urine volume than usual, depressed appetite, nausea, excessive tiredness, dizziness, and bad breath. Prolonged elevation of blood ketones (which are acids) is dangerous as it causes the blood to become acidic resulting eventually in death. Ketosis disappears when carbohydrates are consumed and utilized by the body. 

Coronary Heart Diseases (CHD)

Excess fat intake relates to the prevalence of diseases such as obesity, heart diseases and cancer. Most people require at least 15 to 20 per cent of the kilocalories as fat to provide a palatable diet with sufficient satiety value. Coronary heart disease refers to damage to the heart muscle due to inadequate blood supply from the coronary arteries. Fat deposition takes place in the arteries in the form of plaques and this condition is called atherosclerosis. Plaques contain cholesterol, phospholipids, triglycerides, connective tissue and fibrin. Formation of plaques narrow the blood vessel lumen through which blood flows. Platelets, a type of blood cells, also adhere to the rough surface of plaques. These changes in the blood vessels decrease blood flow and a condition called myocardial infarction (heart attack) may develop, which could be fatal. Many factors'including fat rich diet have been implicated as possible causes of CHD. Adiet low in fat is advisable to prevent such disorders.

i) Dietary fat and cancer: Dietary fat has been linked to cancer based on epidemiological data. Countries with high fat intake have high death rate due to cancer of colon, breast whereas those with low fat consumption have low incidence of cancer.

Effects of higher intake of dietary Fat, Carbohydrates and Proteins

ii) Nicemenn-Pick disease: There are some inherited lipid disorders that needs attention. There is a balance between lipid synthesis and breakdown. The breakdown is initiated by hydrolytic enzymes in the lysosomes (an organelle inside the cell). When breakdown of sphingolipid is altered due to a defect in hydrolytic enzyme, partial breakdown products of this lipid accumulate in the tissues. In Niemann-Pick disease, sphingomyelin accumulates in brain, spleen and liver causing mental retardation and early death.

iii) Tay Sachs disease: In Tay-Sachs disease, ganglioside accumulates in the brain and spleen due to enzyme deficiency. The symptoms of this disease are progressive retardation in development, paralysis, blindness and childhood death. These disorders can now be diagnosed and averted at a very early

stage during pregnancy by genetic counselling.