Jay Tanzman

Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals

Background/Objectives:Walnuts have been shown to reduce serum lipids in short-term well-controlled feeding trials. Little information exists on the effect and sustainability of walnut consumption for longer duration in a free-living situation.Subjects/Methods:A randomized crossover design in which 87 subjects with normal to moderate high plasma total cholesterol were initially assigned to a walnut-supplemented diet or habitual (control) diet for a 6-month period, then switched to the alternate dietary intervention for a second 6-month period. Each subject attended seven clinics 2 months apart. At each clinic, body weight was measured, and in five clinics (months 0, 4, 6, 10 and 12), a blood sample was collected.Results:Our study showed that supplementing a habitual diet with walnuts (12% of total daily energy intake equivalent) improves the plasma lipid profile. This beneficial effect was more significant in subjects with high plasma total cholesterol at baseline. Significant changes in serum concentrations of total cholesterol (P=0.02) and triglycerides (P=0.03) were seen and nearly significant changes in low-density lipoprotein cholesterol (LDL-C) (P=0.06) were found. No significant change was detected in either high-density lipoprotein (HDL) cholesterol LDL to HDL ratio.Conclusions:Including walnuts as part of a habitual diet favorably altered the plasma lipid profile. The lipid-lowering effects of walnuts were more evident among subjects with higher lipid baseline values, precisely those people with greater need of reducing plasma total and LDL-C.

Effect of n-3 fatty acid enriched eggs and organic eggs on serum lutein in free-living lacto-ovo vegetarians

Background/Objective:Lutein is a xanthophyll found in the chloroplasts of dark green leafy vegetables, chromoplasts of fruits, and egg yolk. Dietary, serum and macular lutein are inversely related to the risk of age-related macular degeneration. Although the lutein from egg is known to be more bioavailable than that from spinach, not much is known about lutein bioavailability from n-3 fatty acid enriched eggs and organic eggs, both of which are increasingly available to consumers.Subjects/Methods:We determined the effects of feeding n-3 fatty acid-enriched eggs and organic eggs on serum lutein, zeaxanthin and β-carotene in 20 healthy lacto-ovo-vegetarian (LOV) adults using a single-blind, randomized, crossover study design with a 4-week washout between treatments: six organic eggs or six n-3 fatty acid enriched eggs per week or no egg control for 8weeks each.Results:Serum lutein was significantly higher in both egg treatments (P<0.009) compared with the control, but was not different between the two egg treatments. Serum β-carotene was also higher in the egg groups compared with control but only approached significance (P=0.066). Serum zeaxanthin increased in both egg treatments compared with control but did not reach statistical significance (P=0.139).Conclusion:n-3 fatty acid enriched eggs and organic eggs may both significantly increase serum lutein in healthy LOV consuming a predominately plant-based diet.

Lack of Effect of Walnuts on Serum Levels of Prostate Specific Antigen: A Brief Report

Objective: To examine whether the short-term consumption of walnuts, a food rich in α-linolenic acid, affects levels of serum prostate-specific antigen (PSA), a marker of prostate enlargement, inflammation, and cancer. Methods: Using data from a 12-month randomized crossover study examining the effect of walnut consumption on body composition, we examined whether increased walnut consumption (mean 35 grams daily, 12% total energy) affected serum PSA levels among 40 middle-aged men. Results: There was no significant difference between mean PSA level at the conclusion of the 6-month walnut-supplemented diet (1.05 μg/L, 95% CI [0.81, 1.37]) and the conclusion of the 6-month control diet (1.06 μg/L, 95% CI [0.81, 1.38]) (P = 0.86) (or a mean proportional decrease in PSA of −1%). Conclusions: Our results suggest that short-term consumption of walnuts is unlikely to affect PSA levels adversely among otherwise normal men.