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Isoflavones may not be responsible for soy’s anticancer effect

Research conducted at the University of Illinois suggests that the isoflavones in soy protein may not be the constituents responsible for soy’s anticancer effect, as previously thought. Female rats were treated with purified isoflavones or a soy protein mix with or without isoflavones. The mix without isoflavones was the most effective in reducing the incidence and number of mammary tumors in female rats, though all the treatments had some anti-tumor activity. The researchers suggested that other soy constituents—such as lignans, dietary fiber, or phytic acid—may be acting as antioxidants to inhibit the tumors. The findings were presented April 3 at the American Association for Cancer Research meeting in San Francisco.

Nutraceuticals International, June 2000.

Beta-carotene shown to reduce LDL oxidation

 In a clinical study sponsored by Nutrilite, a 4.5 mg daily supplement of beta-carotene significantly reduced low-density lipoprotein (LDL) oxidation in adults considered to be at risk for heart disease. The study involved 200 male and female subjects aged 35-68 years who were divided into three at-risk groups—smokers, diabetics, and obese—and a healthy control group. All subjects were tested for LDL oxidation susceptibility, given the beta-carotene along with their normal diet for 45 days, then tested again. At the end of the study, oxidized LDLs were reduced by 18, 22, and 21 percent in the smoker, diabetic, and obese groups, respectively. While this difference was significant, LDL oxidation susceptibility for the at-risk subjects at the end of the study was still higher than that of the healthy control group at the beginning of the study.  Researchers from the Rambam Medical Center and National Institute of Oceanography in Haifa, Israel conducted the study. Their findings were presented at the International Conference on Dietary Medicine in April.

Nutrilite Press Release, May 17, 2000.

Extra-virgin is the oil of choice to protect against LDL oxidation

Olive oil

Olea europea

Many Mediterranean populations that consume large amounts of olive oil as part of their diets enjoy a decreased incidence of coronary heart disease. The presence of monounsaturated fatty acids and antioxidants in the diet is directly related to the ability of low-density lipoprotein (LDL) cholesterol to resist oxidation. Oxidative damage of LDL cholesterol has been linked to development of atherosclerosis and other cardiovascular diseases. The present study was conducted to investigate whether differences in olive oil processing methods yield any measurable health benefits. Extra-virgin olive oil (VO) is characterized by very low acidity and retains the fatty acids and antioxidants present in the olives. Refined olive oil (RO), by contrast, has the same fatty acid composition, but because of additional processing lacks the antioxidants present in VO. In this randomized, crossover study, one group of patients with peripheral vascular disease received VO to use in cooking for three months, followed by a three-month washout period, then received RO for the final three months. The other group consumed the oils in the opposite order. Intake of alpha-tocopherol, considered to be a “first line of defense” against LDL oxidation, was higher for patients consuming VO. LDL oxidation rate was lower for patients consuming VO than RO, and during periods when patients consumed VO, a decreased uptake of oxidized LDL by macrophages was also noted. Significant differences in the susceptibility of LDL to oxidation during VO consumption periods led researchers to conclude that the antioxidant composition of VO appears to be more protective against LDL oxidation than RO.

Ramirez-Tortosa M, Urbano G, López-Jurado M, et al. Extra-virgin olive oil increases the resistance of LDL to oxidation more than refined olive oil in free-living men with peripheral vascular disease. J Nutr 1999; 129: 2177-2183.

St. John’s wort

Hypericum perforatum

Another possible mechanism of action for St. John’s wort’s antidepressant activity

St. John’s wort has demonstrated favorable results in the treatment of mild to moderate depression in clinical studies, but the herb’s mechanism of action remains unclear. Previous research has shown that the extract inhibits synaptosomal uptake of serotonin, leading some to suspect that it works in the same manner as the synthetic antidepressant drugs known as selective serotonin reuptake inhibitors (SSRIs). In the present study, researchers verified that St. John’s wort extract did, in fact, inhibit serotonin accumulation in rat brain cortical synaptosomes. However, its mechanism of action appeared to be more closely related to that of reserpine-like compounds than to classic SSRIs in that it depletes storage vesicles of serotonin, thereby raising serotonin concentrations and resulting in apparent reuptake inhibition.

Gobbi M, Dalla Valle F, Ciapparelli C, et al. Hypericum perforatum L. extract does not inhibit 5-HT transporter in rat brain cortex. Arch Pharmacol 1999; 360: 262-269.

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