News Release

Soy Protein With Phytoestrogens Inhibit Atherosclerosis Progression As Well As Premarin

Peer-Reviewed Publication

Atrium Health Wake Forest Baptist

WINSTON-SALEM, NC -- Soy protein with phytoestrogens as well as mammalian estrogen inhibits the progression of atherosclerosis in postmenopausal monkeys, a Wake Forest University Baptist Medical Center research team reported today at an American Heart Association meeting in Santa Fe, N.M.

Estrogen replacement therapy generally is thought to prevent cardiovascular disease in postmenopausal women at least in part because it inhibits atherosclerosis.

And one key issue is whether soy phytoestrogens work as well as Premarin -- the standard mammalian estrogen therapy.

The research team headed by Mary S. Anthony, M.S., a research associate at the Wake Forest University School of Medicine, compared the development of atherosclerosis on the walls of a group of abdominal arteries called the iliac arteries in monkeys fed soy protein containing soy phytoestrogens, in monkeys fed soy protein from which the phytoestrogens had been extracted -- the control group -- and monkeys fed soy protein from which the phytoestrogens had been extracted and given a dose of Premarin.

Anthony and her colleague, Thomas B. Clarkson, DVM, professor of comparative medicine, were comparing the degree of atherosclerosis in the iliac arteries before treatment and three years later.

They found that atherosclerosis progressed in about 64 percent of the animals in the control group, but in only 44 percent of the animals in the phytoestrogen group and 42 percent of the animals in the Premarin group, a significant reduction in progression with the two treatments.

The researchers also concluded:

Premarin had the greatest effect on inhibiting the size of the atherosclerotic plaque, while soy phytoestrogens had an intermediate effect. She suggested that while the soy phytoestrogen "is protective, it may not be quite as robust as [Premarin] in inhibiting changes in plaque size."

Both forms of estrogen replacement therapy were similar in their effects in lowering total cholesterol, low density lipoproteins (LDL) and very low density lipoproteins (VLDL) -- two "bad" forms of cholesterol. Both effects were statistically significant.

Soy protein with phytoestrogen had a greater effect in raising high density lipoproteins (HDL) -- the beneficial form of cholesterol, than did Premarin. The soy protein with phytoestrogen also had a beneficial effect on triglycerides and on another cholesterol component, apolipoprotein A1.

The LDL+VLDL cholesterol was the only cholesterol factor that was significantly associated with a change in the size of the atherosclerotic plaque, accounting for about 20 percent of the variability.

Anthony and Clarkson suggested that the reason may be that phytoestrogens work mostly by altering the cholesterol in the blood, while the Premarin "may have additional effects on the artery wall."

The team held the atherogenic diet constant, so the animals were getting 44 percent of their daily calories from fat, 37 percent from carbohydrates and 19 percent from proteins.

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Contact: Robert Conn, Jim Steele or Mark Wright at 336-716-4587

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