Cholesterol is an essential fat needed for the production of steroid hormones and bile salts. In addition, cholesterol is needed for the function of cell membranes and is especially important for myelin, the insulating material for the nerves in the peripheral nervous system and the brain. Cholesterol is needed to maintain serotonergic brain function and helps to modulate GABA (gamma-aminobutyric acid) receptors. Moreover, cholesterol is an essential activating factor for the developmental protein called sonic hedgehog. Since there are mixed benefits from both high and low cholesterol, all related factors should be considered in the interpretation of results.


Low Cholesterol

Low total cholesterol values (less than 160 mg/dL) are associated with genetic diseases of cholesterol metabolism such as Smith-Lemli-Opitz syndrome (SLOS), Tangier's disease, and abetalipoproteinemia. Low values are more common in vegetarianism, hyperthyroidism, liver disease, use of statin drugs, malabsorption, malnutrition, autism, violent behavior, celiac disease, anxiety, bipolar disease, alcoholism, lung cancer, suicide, depression, and obesity associated with human infection. Research facts from the US Medical Health state that the total serum cholesterol was positively associated with measures of cognitive efficiency, activation, and sociability, suggesting a link between low cholesterol and bad mood. The report even mentions that the number of men whose cholesterol was lower than 160 and who had died from AIDS was four times higher than the number of men who had died from AIDS with a cholesterol above 240.

Optimal Cholesterol

Optimal cholesterol values (between 160-200 mg/dL) Values in this range are generally considered optimal for cardiovascular health. However, higher cholesterol values may be protective against infections. Values within this range may be associated with increased death risk in the elderly (age greater than 70 years). Individuals with frequent infections may want to consider the possible benefits of increasing dietary cholesterol.

High Cholesterol 

High total cholesterol values (greater than 200 mg/dL) are associated with porphyrias, cardiovascular disease, cholestasis, nephritic syndrome, hypothyroidism, oral contraceptives, normal pregnancy, and lipoproteinemia. Many medical authorities recommend serum cholesterol for adults be less than 200 mg/dL based on concerns about cardiovascular health but ignore all of the beneficial effects of cholesterol on brain function and prevention of mental disease. High cholesterol appears to be protective against respiratory illnesses like tuberculosis and a high cholesterol diet has been shown to significantly decrease the length of tuberculosis infections. LDL cholesterol protects against Staphylococcus infections. In an elderly group, people with cholesterol levels less than or equal to 175 mg per dL were twice as likely to die as those with cholesterol levels greater than 226 mg per dL.

The National Institute of Health recommends the following cholesterol levels for children and adults: 

Cholesterol Indicator Table for Children:

Total cholesterol HDL cholesterol LDL cholesterol Result
Less than 200 40 or higher Less than 100 Good
200–239 n/a 130–159 Borderline
240 or higher n/a 160 or higher High
n/a less than 40 n/a Low

Cholesterol Indicator Table for Adults:

Total cholesterol HDL cholesterol LDL cholesterol Result
170 or less 45 or higher 110 or less Good
170–199 40-45 110–129 Borderline
200 or higher n/a greater than 130 High
n/a less than 40 n/a Low

Live a healthy, active lifestyle that includes eating a healthful diet and getting plenty of exercises to keep cholesterol levels in check.