Need to establish threshold soy protein intake for cholesterol reduction

Cellular Mechanisms of Oxidative Stress and Action in Melanoma

Most melanomas occur on the skin, but a small percentage of these life-threatening cancers affect other parts of the body, such as the eye and mucous membranes, including the mouth. Given that most melanomas are caused by ultraviolet radiation (UV) exposure, close attention has been paid to the impact of oxidative stress on these tumors. The possibility that key epigenetic enzymes cannot act on a DNA altered by oxidative stress has opened new perspectives. Therefore, much attention has been paid to the alteration of DNA methylation by oxidative stress. We review the current evidence about (i) the role of oxidative stress in melanoma initiation and progression; (ii) the mechanisms by which ROS influence the DNA methylation pattern of transformed melanocytes; (iii) the transformative potential of oxidative stress-induced changes in global and/or local gene methylation and expression; (iv) the employment of this epimutation as a biomarker for melanoma diagnosis, prognosis, and drug resistance evaluation; (v) the impact of this new knowledge in clinical practice for melanoma treatment.

The effects of isoflavones combined with soy protein on lipid profiles, C-reactive protein and cardiovascular risk among postmenopausal Chinese women

BACKGROUND & AIMS

Observational studies note that regular dietary soy protein intake (6-11 g day(-1)) has a significant association with lower blood lipids; however, these observations have not been confirmed by clinical trials. This study aimed to ascertain the effects of moderate intake of soy protein (15 g) with isoflavones or isoflavones alone on serum lipid profiles, inflammatory markers (C-reactive protein and uric acid) and composite cardiovascular risk in Chinese postmenopausal, prediabetic women.

METHODS AND RESULTS

A double-blind randomised, placebo-controlled trial was conducted among 180 postmenopausal Chinese women with prediabetes or early untreated diabetes, aged 46-70 years and, on average, 6.0 years since menopause. Participants were randomly assigned to one of the three arms to receive 15-g soy protein and 100-mg isoflavone (Soy group), or 15-g milk protein and 100 mg isoflavone (Iso group) or 15-g milk protein (placebo group) on a daily basis for 6 months. The results showed that no significant difference was observed in serum high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), triaclyglycerol (TG), high sensitive C-reactive protein and a composite 10-year cardiovascular risk between the three groups at both 3 and 6 months. Serum uric acid marginally increased by 1.22% in the Soy group and decreased by 4.28% and 4.82% in the Iso and placebo groups at 3 months (P = 0.087), but no difference was observed at 6 months (P = 0.264).

CONCLUSION

Soy protein with isoflavones or isoflavones alone at the provided dosage showed no significantly beneficial effects on measured cardiovascular risk factors in postmenopausal Chinese women with early hyperglycaemia.

The role of soy in vegetarian diets

Soyfoods have long been prized among vegetarians for both their high protein content and versatility. Soybeans differ markedly in macronutrient content from other legumes, being much higher in fat and protein, and lower in carbohydrate. In recent years however, soyfoods and specific soybean constituents, especially isoflavones, have been the subject of an impressive amount of research. Nearly 2,000 soy-related papers are published annually. This research has focused primarily on the benefits that soyfoods may provide independent of their nutrient content. There is particular interest in the role that soyfoods have in reducing risk of heart disease, osteoporosis and certain forms of cancer. However, the estrogen-like effects of isoflavones observed in animal studies have also raised concerns about potential harmful effects of soyfood consumption. This review addresses questions related to soy and chronic disease risk, provides recommendations for optimal intakes, and discusses potential contraindications. As reviewed, the evidence indicates that, with the exception of those individuals allergic to soy protein, soyfoods can play a beneficial role in the diets of vegetarians. Concerns about adverse effects are not supported by the clinical or epidemiologic literature. Based on the soy intake associated with health benefits in the epidemiologic studies and the benefits noted in clinical trials, optimal adult soy intake would appear to be between two and four servings per day.

Oxidative stress and DNA methylation in prostate cancer

The protective effects of fruits, vegetables, and other foods on prostate cancer may be due to their antioxidant properties. An imbalance in the oxidative stress/antioxidant status is observed in prostate cancer patients. Genome oxidative damage in prostate cancer patients is associated with higher lipid peroxidation and lower antioxidant levels. Oxygen radicals are associated with different steps of carcinogenesis, including structural DNA damage, epigenetic changes, and protein and lipid alterations. Epigenetics affects genetic regulation, cellular differentiation, embryology, aging, cancer, and other diseases. DNA methylation is perhaps the most extensively studied epigenetic modification, which plays an important role in the regulation of gene expression and chromatin architecture, in association with histone modification and other chromatin-associated proteins. This review will provide a broad overview of the interplay of oxidative stress and DNA methylation, DNA methylation changes in regulation of gene expression, lifestyle changes for prostate cancer prevention, DNA methylation as biomarkers for prostate cancer, methods for detection of methylation, and clinical application of DNA methylation inhibitors for epigenetic therapy.

Systematic review, meta-analysis and regression of randomised controlled trials reporting an association between an intake of circa 25 g soya protein per day and blood cholesterol

AIMS

To determine the effect of a daily intake of circa 25 g soya protein on blood lipids in adults with normal or mildly elevated cholesterolaemia.

METHODS

Medline and other scientific databases were searched to identify randomised controlled trials (RCTs); these were systematically reviewed against pre-determined criteria. Eligible RCTs evaluated the effect of 25 g (range 15-40 g) soya protein on measures of blood lipids. Results from RCTs were pooled using standard meta-analysis methods.

RESULTS

Thirty studies containing 42 treatment arms (n=2913), with an average soya protein intake of 26.9 g met the inclusion criteria. Soya protein inclusion led to reductions in standard difference in mean low density lipoprotein (LDL), total cholesterol and blood triglycerides of 0.23 mmol/L (95% confidence interval (CI) -0.160 to -0.306, p<0.0001), 0.22 mmol/L (95% CI -0.142 to -0.291, p<0.0001) and 0.08 mmol/L (95% CI -0.004 to -0.158, p=0.04), respectively. There was no effect on mean difference in apolipoprotein A (ApoA), but ApoB was reduced by 0.021 g/L (p=0.01) in the soya group. Meta-regression analysis indicated no dose response relationship between soya protein intake in the range of 15-40 g and standard difference in LDL or HDL. All data were tested for heterogeneity and none identified.

CONCLUSIONS

The inclusion of modest amounts soya protein (ca. 25 g) into the diet of adults with normal or mild hypercholesterolaemia resulted in small, highly significant reductions in total and LDL cholesterol, equivalent to ca. 6% LDL reduction. This practically achievable intake, particularly when combined with other dietary measures, can make a useful contribution to blood cholesterol management.

Isoflavones--safe food additives or dangerous drugs?

The sales volume of products containing isoflavone has increased since the publication of the Women's Health Initiative. The many apparently contradictory results published on the effects of isoflavones on a variety of estrogen-regulated organs point to both beneficial as well as adverse effects on human health. It is of particular importance that psychovegetative climacteric complaints such as hot flushes are, if at all, only slightly influenced by isoflavones. The substances appear to have weak anti-osteoporotic effect. Their anti-atherosclerotic action is debatable, as not all authors find any beneficial effect on lipids. Most importantly, there is dispute as to whether isoflavones derived from soy or red clover have negative, positive or any effect at all on the mammary gland or endometrium. It is beyond any doubt that soy products may have cancer preventing properties in a variety of organs including the mammary gland. However, these properties may only be exerted if the developing organ was under the influence of isoflavones during childhood and puberty. This may also explain the often quoted "Japanese Phenomenon", the fact that breast cancer occurs to a lesser extent in Japanese women. When administered to isoflavone "inexperienced" women at the time of menopause, the phytoestrogens appear to share the same effects as estrogen used in classical preparations for hormone replacement therapy, i.e. they may stimulate the proliferation of endometrial and mammary gland tissue with at present unknown and unpredictable risk to these organs. Therefore, the following question arises for the clinician: Why should soy or red clover products containing isoflavone be recommended, if the positive effects are only negligible but the adverse effects serious?