Fw: Too much sugar turns off gene that controls the effects of sex steroids

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Eating too much fructose and glucose can turn off the gene that regulates

the levels of active testosterone and estrogen in the body, shows a new

study in mice and human cell cultures that's published this month in the

Journal of Clinical Investigation. This discovery reinforces public health

advice to eat complex carbohydrates and avoid sugar.

Table sugar is made of glucose and fructose, while fructose is also commonly

used in sweetened beverages, syrups, and low-fat food products. Estimates

suggest North Americans consume 33 kg of refined sugar and an additional 20

kg of high fructose corn syrup per person per year.

Glucose and fructose are metabolized in the liver. When there's too much

sugar in the diet, the liver converts it to lipid. Using a mouse model and

human liver cell cultures, the scientists discovered that the increased

production of lipid shut down a gene called SHBG (sex hormone binding

globulin), reducing the amount of SHBG protein in the blood. SHBG protein

plays a key role in controlling the amount of testosterone and estrogen

that's available throughout the body.

If there's less SHBG protein, then more testosterone and estrogen will be

released throughout the body, which is associated with an increased risk of

acne, infertility, polycystic ovaries, and uterine cancer in overweight

women. Abnormal amounts of SHBG also disturb the delicate balance between

estrogen and testosterone, which is associated with the development of

cardiovascular disease, especially in women.

" We discovered that low levels of SHBG in a person's blood means the liver's

metabolic state is out of whack - because of inappropriate diet or something

that's inherently wrong with the liver - long before there are any disease

symptoms, " says Dr. Geoffrey Hammond, the study's principal investigator,

scientific director of the Child & Family Research Institute in Vancouver,

Canada, and professor in the Department of Obstetrics & Gynecology at the

University of British Columbia.

" With this new understanding, we can now use SHBG as a biomarker for

monitoring liver function well before symptoms arise, " says Dr Hammond, who

is a Tier 1 Canada Research Chair in Reproductive Health. " We can also use

it for determining the effectiveness of dietary interventions and drugs

aimed at improving the liver's metabolic state. "

2 Physicians have traditionally measured SHBG in the blood to determine a

patient's amount of free testosterone, which is key information for

diagnosing hormonal disorders.

In addition, SHBG levels are used to indicate an individual's risk for

developing type 2 diabetes and cardiovascular disease.

The discovery dispels the earlier assumption that too much insulin reduces

SHBG, a view which arose from the observation that overweight, pre-diabetic

individuals have high levels of insulin and low levels of SHBG. This new

study proves that insulin is not to blame and that it's actually the liver's

metabolism of sugar that counts.

This research was supported by a grant from the Canadian Institutes of

Health Research, the Foundation for Health Research, and the

BC Children's Hospital Foundation.

The Child & Family Research Institute is dedicated to world-class research

at the Children's and Women's Health Campus. It is the largest research

institute of its kind in Western Canada and it is supported by the BC

Children's Hospital Foundation. Research is conducted in the areas of

community child heath, diabetes, applied health research and evaluation,

infectious and inflammatory diseases, molecular medicine and therapeutics,

oncology, reproductive health, nutrition, genetics, immunology,

informatics,neurobiology and mental health. Incorporated in 1995, the

Institute works in close partnership with the University of British

Columbia, BC Children's Hospital and Sunny Hill Health Centre for Children,

and BC Women's Hospital & Health Centre, which are agencies of the

Provincial Health Services Authority.

For more information or to arrange an interview, please contact:

Kohm, Communications Director Child & Family Research Institute