Is equol the key to the efficacy of soy foods?

Should dairy be recommended as part of a healthy vegetarian diet? Point

A benefit-risk evaluation of the evidence for including dairy foods in the diet is presented. For many persons dairy products provide a substantial portion of essential nutrients, but especially calcium, potassium, and magnesium. Dietary supplements and fortified foods can be alternative sources of these nutrients, although other components of dairy foods such as amino acid composition and conjugated linoleic acid may be instrumental in the benefits associated with dairy product consumption for bone health and reduced risk of stroke, metabolic syndrome, and some cancers. Newer evidence shows that protein-induced calciuria does not have a detrimental effect on net calcium retention, and the concentrations of hormones in milk are not outside of the range of endogenous concentrations. Increased dietary protein, including from milk, can elevate serum concentrations of insulin-like growth factor I, which has an unknown relation to cancer. The concern over consumption of milk leading to increased risk of prostate cancer through reduction of serum 1,25-dihydroxyvitamin D, a potent anti-prostate cancer hormone, has been resolved with new evidence that local production of this hormone is independent of diet. Overall, evidence suggests that being a lactovegetarian has greater health benefits and reduced health risks than being a vegan.

Cancer incidence in vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford)

BACKGROUND

Few prospective studies have examined cancer incidence among vegetarians.

OBJECTIVE

We report cancer incidence among vegetarians and nonvegetarians in the European Prospective Investigation into Cancer and Nutrition-Oxford (EPIC-Oxford) study.

DESIGN

This was a prospective study of 63,550 men and women recruited throughout the United Kingdom in the 1990s. Cancer incidence was followed through nationwide cancer registries.

RESULTS

The standardized incidence ratio for all malignant neoplasms for all participants was 72% (95% CI: 69%, 75%). The standardized incidence ratios for colorectal cancer were 84% (95% CI: 73%, 95%) among nonvegetarians and 102% (95% CI: 80%, 129%) among vegetarians. In a comparison of vegetarians with meat eaters and after adjustment for age, sex, and smoking, the incidence rate ratio for all malignant neoplasms was 0.89 (95% CI: 0.80, 1.00). The incidence rate ratio for colorectal cancer in vegetarians compared with meat eaters was 1.39 (95% CI: 1.01, 1.91).

CONCLUSIONS

The overall cancer incidence rates of both the vegetarians and the nonvegetarians in this study are low compared with national rates. Within the study, the incidence of all cancers combined was lower among vegetarians than among meat eaters, but the incidence of colorectal cancer was higher in vegetarians than in meat eaters.

The health implications of soy infant formula

Soy formula (SF) has been fed to millions of infants worldwide. It has been shown to promote growth and development as well as milk-based formula (MF). Controversy has developed over the adequacy and safety of SF. Most concerns are based on in vivo and in vitro data that raise the possibility of estrogenic effects of isoflavones contained in SF. There are few studies of children who were fed SF, and thus insufficient data are available to judge if SF feeding results in clinically significant developmental effects and if there are any long-term health consequences (adverse or beneficial). However, the Arkansas Children's Nutrition Center is conducting a prospective longitudinal study comparing growth, development, and health of breastfed children with formula-fed (SF and MF) children from birth through age 6 y. After 5 y of study, children in all 3 groups (n > 300) are growing and developing within normal limits, and there are no indications of adverse effects in the soy-fed children. Neonatal pig studies comparing SF, MF, and breast milk (BM) have shown diet-specific gene expression profiles in various target tissues. Therefore, although SF differed significantly from BM, MF also differed from BM, and SF differed from MF. Nonetheless, these animals grew and developed normally, and SF piglets had several health benefits (eg, increased bone quality) and no observable adverse effects. Thus, to date, our results suggest that SF supports normal growth and may have advantages in promoting bone development.

Walnuts and fatty fish influence different serum lipid fractions in normal to mildly hyperlipidemic individuals: a randomized controlled study

BACKGROUND

Increased consumption of n-3 (omega-3) fatty acids decreases the incidence of coronary heart disease (CHD).

OBJECTIVE

The objective was to determine whether walnuts (plant n-3 fatty acid) and fatty fish (marine n-3 fatty acid) have similar effects on serum lipid markers at intakes recommended for primary prevention of CHD.

DESIGN

In a randomized crossover feeding trial, 25 normal to mildly hyperlipidemic adults consumed 3 isoenergetic diets ( approximately 30% total fat and <10% saturated fat) for 4 wk each: a control diet (no nuts or fish), a walnut diet (42.5 g walnuts/10.1 mJ), or a fish diet (113 g salmon, twice/wk). Fasting blood was drawn at baseline and at the end of each diet period and analyzed for serum lipids.

RESULTS

Serum total cholesterol and LDL cholesterol concentrations in adults who followed the walnut diet (4.87 +/- 0.18 and 2.77 +/- 0.15 mmol/L, respectively) were lower than in those who followed the control diet (5.14 +/- 0.18 and 3.06 +/- 0.15 mmol/L, respectively) and those who followed the fish diet (5.33 +/- 0.18 and 3.2 +/- 0.15 mmol/L, respectively; P < 0.0001). The fish diet resulted in decreased serum triglyceride and increased HDL-cholesterol concentrations (1.0 +/- 0.11 and 1.23 +/- 0.05 mmol/L, respectively) compared with the control diet (1.12 +/- 0.11 and 1.19 +/- 0.05 mmol/L, respectively) and the walnut diet (1.11 +/- 0.11 mmol/L, P < 0.05, and 1.18 +/- 0.05 mmol/L, P < 0.001, respectively). The ratios of total cholesterol:HDL cholesterol, LDL cholesterol:HDL cholesterol, and apolipoprotein B:apolipoprotein A-I were lower (P < 0.05) in those who followed the walnut diet compared with those who followed the control and fish diets.

CONCLUSION

Including walnuts and fatty fish in a healthy diet lowered serum cholesterol and triglyceride concentrations, respectively, which affects CHD risk favorably.

Nuts and novel biomarkers of cardiovascular disease

Nuts are energy-dense foods, rich in total fat and unsaturated fatty acids. The favorable fatty acid profile probably contributes to the beneficial effects of nut consumption observed in epidemiologic studies (prevention of coronary heart disease and diabetes) and feeding trials (cholesterol lowering). Besides fat, the complex matrices of nuts contain many bioactive compounds: vegetable protein, fiber, minerals, tocopherols, and phenolic compounds. By virtue of their unique composition, nuts are likely to benefit newer cardiovascular risk biomarkers, such as LDL oxidizability, soluble inflammatory molecules, and endothelial dysfunction. Protection of LDL oxidation by nut intake has been documented in some, but not all, clinical studies. In one study, feeding one daily serving of mixed nuts was associated with lower oxidized LDL concentrations. Regarding inflammation, cross-sectional studies have shown that nut consumption is associated with lower concentrations of circulating inflammatory molecules and higher plasma adiponectin, a potent antiinflammatory adipokine. Clinical studies with nuts have documented reduced inflammatory cytokine concentrations but no consistent changes of C-reactive protein. Only walnuts have been formally tested for effects on endothelial function. After both walnut diets and single walnut meals, favorable vasoreactivity changes have been observed. Walnut consumption also reduced expression of endothelin 1, a potent endothelial activator, in an animal model of accelerated atherosclerosis. Beneficial effects on vascular reactivity may be ascribed to several constituents of walnuts: l-arginine, the precursor of nitric oxide, alpha-linolenic acid, and phenolic antioxidants. Although more studies are warranted, the emerging picture is that nut consumption beneficially influences cardiovascular risk beyond cholesterol lowering.

Plant foods and plant-based diets: protective against childhood obesity?

The objective of this article is to review the epidemiologic literature examining the role of plant foods and plant-based diets in the prevention of childhood obesity. Available data suggest a protective effect of ready-to-eat cereal on risk of obesity, although prospective studies are still needed. Studies on fruit and vegetables; grains other than cereal; high-protein foods, including beans, legumes, and soy; fiber; and plant-based dietary patterns are inconsistent or generally null. The evidence base is limited, and most studies are fraught with methodologic limitations, including cross-sectional design, inadequate adjustment for potential confounders, and lack of consideration of reporting errors, stage of growth, and genetic influences. Well-designed prospective studies are needed. The lack of evidence showing an association between plant-based diets and childhood obesity does not mean that such diets should not be encouraged. Plant foods are highlighted in the Dietary Guidelines for Americans, and children do not meet the current recommendations for most plant foods. Although the advice to consume a plant-based, low-energy-dense diet is sound, ethical questions arise concerning the relatively high price of these diets in the United States and the way in which such diets are perceived in other parts of the world. Reducing the burden of childhood obesity, eliminating health disparities, and preventing the further spread of the disease around the globe will require not only policy interventions to ensure that plant foods are affordable and accessible to children of all income levels but also awareness of sociocultural norms that affect consumption.

Geophysics and nutritional science: toward a novel, unified paradigm

This article discusses a few basic geophysical processes, which collectively indicate that several nutritionally adverse elements of current Western diets also yield environmentally harmful food consumption patterns. We address oceanic dead zones, which are at the confluence of oceanography, aquatic chemistry, and agronomy and which are a clear environmental problem, and agriculture's effects on the surface heat budget. These exemplify the unknown, complex, and sometimes unexpected large-scale environmental effects of agriculture. We delineate the significant alignment in purpose between nutritional and environmental sciences. We identify red meat, and to a lesser extent the broader animal-based portion of the diet, as having the greatest environmental effect, with clear nutritional parallels.

The relation of alpha-linolenic acid to the risk of prostate cancer: a systematic review and meta-analysis

BACKGROUND

alpha-Linolenic acid (ALA; 18:3n-3) has been associated inconsistently with an increased risk of prostate cancer. Additional studies have become available since the publication of 2 previous meta-analyses.

OBJECTIVE

The objective was to review the published data on the relation between ALA and prostate cancer.

DESIGN

We conducted a systematic review to identify studies that included data on ALA and risk of prostate cancer. Data were pooled from studies that compared the highest ALA quantile with the lowest ALA quantile, and risk estimates were combined by using a random-effects model.

RESULTS

The relation between ALA and prostate cancer is inconsistent across studies. We pooled data from 8 case-control and 8 prospective studies. The summary estimate revealed that high ALA dietary intakes or tissue concentrations are weakly associated with prostate cancer risk (relative risk [RR]: 1.20; 95% CI: 1.01, 1.43). When examined by study type (ie, retrospective compared with prospective or dietary ALA compared with tissue concentration) or by decade of publication, only the 6 studies examining blood or tissue ALA concentrations revealed a statistically significant association. With the exception of these studies, there was significant heterogeneity and evidence of publication bias. After adjustment for publication bias, there was no association between ALA and prostate cancer (RR: 0.96; 95% CI: 0.79, 1.17).

CONCLUSIONS

Studies examining the relation between ALA and prostate cancer have produced inconsistent findings. High ALA intakes or high blood and adipose tissue concentrations of ALA may be associated with a small increased risk of prostate cancer. However, these conclusions are qualified because of the heterogeneity across studies and the likelihood of publication bias.

Dietary change and reduced breast cancer events among women without hot flashes after treatment of early-stage breast cancer: subgroup analysis of the Women's Healthy Eating and Living Study

BACKGROUND

A diet high in vegetables, fruit, and fiber and low in fat decreased additional risk of secondary breast cancer events in women without hot flashes (HF-) compared with that in women with hot flashes (HF+), possibly through lowered concentrations of circulating estrogens.

OBJECTIVE

The objective was to investigate the intervention effect by baseline quartiles of dietary pattern among breast cancer survivors in the HF- subgroup of the Women's Healthy Eating and Living Study.

DESIGN

A randomized controlled trial compared a putative cancer prevention diet with a diet of 5 servings of vegetables and fruit daily in early-stage breast cancer survivors. Participants did not experience hot flashes at baseline (n = 896). We confirmed cancer status for 96% of participants approximately 7.3 y after enrollment.

RESULTS

The study intervention achieved a large between-group difference in dietary pattern that, at 4 y, was not significantly different across baseline quartiles of dietary pattern. The intervention group experienced fewer breast cancer events than did the comparison group for all of the baseline quartiles. This difference was significant only in upper baseline quartiles of intake of vegetables, fruit, and fiber and in the lowest quartile of fat. A significant trend for fewer breast cancer events was observed across quartiles of vegetable-fruit and fiber consumption.

CONCLUSIONS

The secondary analysis showing the decreased risk in the HF- subgroup was not explained by amount of change in dietary pattern achieved. The difference was strongest in the quartile with the most putatively cancer-preventive dietary pattern at baseline.