The Japan Society for Lipid Nutrition has drawn up new guidelines stating that high cholesterol levels are better for living longer, defying conventional wisdom.
There are two kinds of cholesterol -- low-density lipoprotein (LDL) that is considered "bad," and high-density lipoprotein (HDL), which is regarded as "good" cholesterol. LDL cholesterol is delivered to cells throughout the body, while HDL is excess cholesterol collected from the body.
The Japan Atherosclerosis Society, an organization focusing on lifestyle-related diseases, has advocated people lower their LDL cholesterol levels by improving dietary habits and using medication, because high LDL levels could cause heart disease.
In 2007, the society set diagnostic criteria for hyperlipemia, or elevated levels of lipids in the bloodstream, flagging LDL cholesterol levels of at least 140 mg/dl and HDL levels less than 40 mg/dl as dangerous for both men and women.
"According to domestic and foreign research, the higher LDL levels become, the more arterial stiffening advances. Correspondingly, incidence of heart disease also rises. We concluded that LDL cholesterol levels more than 140 mg/dl could easily cause heart disease," said Hirotsugu Ueshima, professor emeritus at Shiga University of Medical Science, who devised the atherosclerosis society's criteria.
However, Tomohito Hamazaki, a professor at Toyama University's Institute of Natural Medicine, who compiled the new cholesterol levels guidelines for the Japan Society for Lipid Nutrition, countered Ueshima's argument. "When examining all causes of death, such as cancer, pneumonia and heart disease, the number of deaths attributable to LDL cholesterol levels exceeding 140 mg/dl is less than people with lower LDL cholesterol levels."
The lipid nutrition society guidelines do not posit new criteria, but Hamazaki cited some study results to prove his thesis.
According to a eight-year study of about 26,000 men and women in Isehara, Kanagawa Prefecture, the death rate of men whose LDL cholesterol levels were between 100 mg/dl and 160 mg/dl was low, while the rate rose for those with LDL cholesterol levels of less than 100 mg/dl.
The LDL figures exhibited less influence on women, but the death rate still rose for women with LDL cholesterol levels less than 120 mg/dl.
A separate study of 16,850 patients nationwide who suffered cerebral stroke showed the death rate of people with hyperlipemia who died from a cerebral stroke was lower, and their symptoms more slight.
"Cholesterol is an essential component for the creation of cell membranes and hormones. It's not recommended to lower LDL figures by means of dietary intake and medication," Hamazaki said.
Additional differences exist between men and women's LDL figures.
"When women reach menopause, their cholesterol figures rise sharply, yet do not affect the arteriosclerosis process or development of heart diseases. At the very least, cholesterol criteria is not necessary for women," Hiroyuki Tanaka, director of Niko Clinic in Takeo, Saga Prefecture.
The society's for lipid nutrition's recently issued guidelines should become an opportunity to highlight the need for treatments to focus on the difference between genders and the related disease risks.
Explore further: Researchers to look for patterns in patient data from ManagingLife's pain diary app