Eating Greens Good for Men

[Guest guest]

http://www.research.buffalo.edu/quarterly/vol09/num02/f1.shtml

" Eating Greens " Good for Men

Plant-based fats may lower prostate cancer risk

Article published Summer 1999

 

Over the past few years, there has been growing evidence of a link between high

levels of testosterone and the risk for

developing prostate cancer. Recently, scientists at the University at Buffalo

contributed to this area of research when

they found that plant-based fats may reduce the levels of testosterone in the

blood, as well as certain enzymes that

metabolize testosterone into more active forms.

 

Specifically, the scientists discovered that by feeding rats a diet rich in

phytosterols-the type of fat found in

plants-they were able to reduce testosterone in the bloodstream by 33 percent.

 

In addition, they found that the levels of two enzymes, 5-alpha reductase and

aromatase, were reduced by 44 percent and

55 percent, respectively, which is significant because these enzymes metabolize

testosterone into end-products that also

are implicated in the development of prostate cancer.

 

The study was led by Atif Awad, PhD, head of the nutrition program in UB's

Department of Physical Therapy, Exercise and

Nutrition Science, whose work was supported by a $45,000 grant from the Allen

Foundation. Awad and his colleagues have

been trying to understand the mechanisms responsible for vegetarians' lower

rates of hormone-dependent cancers and for

the lower mortality rate from prostate cancer in Asian countries, where

populations eat little meat. Because fats are

known to play a role in the development of several cancers, his group has been

focusing on the phytosterols for possible

answers.

 

The objective of the current study was to examine the influence of vegetable

fats on the metabolism of testosterone in

liver, testis and prostate tissue in rats. During metabolism, interaction with

the enzyme 5-alpha reductase changes

testosterone into more active forms, while interaction with the enzyme aromatase

converts it to estrogen, also

considered a possible risk factor for prostate cancer.

 

Knowing that prostate cancer doesn't develop in men castrated before puberty or

in men who have low levels of 5-alpha

reductase suggested to Awad's group that suppressing the action of the enzyme

might be useful in preventing prostate

cancer in high-risk groups.

 

To determine if high levels of phytosterols could inhibit these enzymes, the

researchers fed one group of rats a

standard diet; a second, control group ate the standard diet plus cholic acid,

which stimulates the absorption of

vegetable fats. A third group ate a standard diet enhanced with a mixture of

phytosterols, plus cholic acid.

 

Results showed that rats fed the phytosterol diet had between 33 and 48 percent

less testosterone than the animals that

received no additional phytosterols. There was no difference in serum

testosterone levels between the basal and control

groups.

 

The enhanced diet reduced the activity of 5-alpha reductase by 44 percent in the

liver and by 33 percent in the prostate

but did not affect the enzyme's activity in the testis, results showed.

Phytosterols reduced the activity of aromatase

by 57 percent in the prostate but had no effect in the liver or testis.

 

Awad says his research team is continuing to examine exactly how phytosterols

bring about these changes, but he believes

one pathway involves the " fluidity " of the membranes that harbor the enzymes.

" Every enzyme requires a specific fluidity

in the membrane in which it resides in order to be activated, " he says. " If the

membrane is too fluid, the enzymes may

not function properly. "

 

Other options include the possibility that phytosterols compete with

testosterone and its products of metabolism for the

enzyme's active receptors, or that they reduce production of the enzymes

themselves. " Either way, the combined effect of

reducing levels of testosterone and the activity of its two main enzymes

suggests that a diet high in foods containing

phytosterols could help reduce the risk of prostate cancer, " Awad says.

 

For more information on this study, e-mail Dr. Awad at awad; or

refer to the paper published on this

work in the Journal of Nutritional Biochemistry, Volume 9, pp. 712-717, 1998.

========================

 

See I told you Veggies were good for you!

 

========================

Good Health & Long Life,

Greg Watson, gowatson

USDA database (food breakdown) http://www.nal.usda.gov/fnic/foodcomp/

PubMed (research papers) http://www.ncbi.nlm.nih.gov/entrez/query.fcgi

DWIDP (nutrient analysis) http://www.walford.com/dwdemo/dw2b63demo.exe

KIM (omega analysis) http://ods.od.nih.gov/eicosanoids/KIM_Install.exe