Walnut Intake Research Articles

Walnut ingestion in adults at risk for diabetes: effects on body composition, diet quality, and cardiac risk measures

BackgroundDespite their energy density, walnuts can be included in the diet without adverse effects on weight or body composition. The effect of habitual walnut intake on total calorie intake is...

Effects of short-term walnut consumption on human microvascular function and its relationship to plasma epoxide content

Improved vascular function after the incorporation of walnuts into controlled or high-fat diets has been reported; however, the mechanism(s) underlying this effect of walnuts is(are) poorly defined. The objective of the current study was to evaluate the acute and short-term effects of walnut intake on changes in microvascular function and the relationship of these effects to plasma epoxides, the cytochrome-P450-derived metabolites of fatty acids. Thirty-eight hypercholesterolemic postmenopausal women were randomized to 4 weeks of 5 g or 40 g of daily walnut intake. All outcomes were measured after an overnight fast and 4 h after walnut intake. Microvascular function, assessed as the reactive hyperemia index (RHI), was the primary outcome measure, with serum lipids and plasma epoxides as secondary measures. Compared to 5 g of daily walnut intake, consuming 40 g/d of walnuts for 4 weeks increased the RHI and Framingham RHI. Total cholesterol and low- and high-density cholesterol did not significantly change after walnut intake. The change in RHI after 4 weeks of walnut intake was associated with the change in the sum of plasma epoxides (r=0.65, P=.002) but not with the change in the sum of plasma hydroxyeicosatetraenoic acids. Of the individual plasma epoxides, arachidonic-acid-derived 14(15)-epoxyeicosatrienoic acid was most strongly associated with the change in microvascular function (r=0.72, P<.001). These data support the concept that the intake of walnut-derived fatty acids can favorably affect plasma epoxide production, resulting in improved microvascular function.

The Change in Human Microvascular Function and its Relationship to Plasma Epoxide Content After Short‐Term Walnut Intake

Walnuts are a source of alpha‐linolenic acid (ALA) and linoleic acid (LA). We examined the effects of short‐term walnut intake on the reactive hyperemia index (RHI), a measure of microvascular function. We hypothesized that 4 weeks of 40g/day of walnuts would improve RHI compared to 5g/day of walnuts in hypercholesterolemic postmenopausal women. Microvascular function is influenced, in part, by locally produced vasodilators, such as nitric oxide and endothelial‐derived hyperpolarizing factor (EDHF). Putative EDHF include cytochrome P450 epoxides of arachidonic acid (AA) known as the EpETrEs. Epoxides are also derived from ALA (EpODE) and LA (EpODE); however, their vascular influence is currently undefined. Four weeks of 40g/day of walnut intake increased RHI compared to 5g/day (2.61 ± 0.10 versus 2.24 ± 0.12, respectively, p = 0.027). Plasma EpODE and EpOME were significantly increased with 40g/day compared to 5g/day of walnut intake. The total change in plasma epoxides was strongly associated with the change in RHI (r=0.65, p = 0.002). There was a strong association between the change in EpODE, EpOME, and EpETrE, as well as, these epoxides and the change in RHI (|r|=0.56, p &lt; 0.01); with the strongest association observed for 14(15)‐EpETrE (r=0.72, p &lt; 0.001). These data are consistent with reports of improved vascular function with walnut consumption, and provide new insights into potential relationships between changes in microvascular function and plasma epoxides after walnut intake.

A cross sectional study of the association between walnut consumption and cognitive function among adult US populations represented in NHANES.

To examine the association between walnut consumption and measures of cognitive function in the US population. Nationally representative cross sectional study using 24 hour dietary recalls of intakes to assess walnut and other nut consumption as compared to the group reporting no nut consumption. 1988-1994 and 1999-2002 rounds of the National Health and Nutrition Examination Survey (NHANES). Representative weighted sample of US adults 20 to 90 years of age. The Neurobehavioral Evaluation System 2 (NES2), consisting of simple reaction time (SRTT), symbol digit substitution (SDST), the single digit learning (SDLT), Story Recall (SRT) and digit-symbol substitution (DSST) tests. Adults 20-59 years old reporting walnut consumption of an average of 10.3 g/d required 16.4ms less time to respond on the SRTT, P=0.03, and 0.39s less for the SDST, P=0.01. SDLT scores were also significantly lower by 2.38s (P=0.05). Similar results were obtained when tertiles of walnut consumption were examined in trend analyses. Significantly better outcomes were noted in all cognitive test scores among those with higher walnut consumption (P < 0.01). Among adults 60 years and older, walnut consumers averaged 13.1 g/d, scored 7.1 percentile points higher, P=0.03 on the SRT and 7.3 percentile points higher on the DSST, P=0.05. Here also trend analyses indicate significant improvements in all cognitive test scores (P < 0.01) except for SRTT (P = 0.06) in the fully adjusted models. These significant, positive associations between walnut consumption and cognitive functions among all adults, regardless of age, gender or ethnicity suggest that daily walnut intake may be a simple beneficial dietary behavior.

Mental imagery interventions reduce subsequent food intake only when self-regulatory resources are available.

Research has shown that imagining food consumption leads to food-specific habituation effects. In the present research, we replicated these effects and further examined whether the depletion of self-regulatory resources would reduce the habituation effects of imagined food consumption. Since self-regulatory resources have been shown to reduce habituation effects during the perception of emotional stimuli, we expected a reduction in habituation effects from imagined food consumption when self-regulatory resources were depleted. In Study 1, we replicated habituation effects as a response to imagining gummy bear consumption with a high (36) and medium number (18) of repetitions in a camouflaged taste test. Participants imagining gummy bear intake showed decreased food intake compared with participants who imagined putting a coin into a laundry machine. The number of repetitions did not significantly moderate the observed habituation effect. In Study 2, we investigated whether self-regulatory depletion would impede habituation effects evoked by the imagination of walnut consumption. Participants in a depleted state did not show a reduction in food intake after imagining walnut intake compared with participants in a non-depleted state. We discuss directions for future research and processes that might underlie the observed moderating effect of self-regulatory resources.

Inverse association between the frequency of nut consumption and obesity among Iranian population: Isfahan Healthy Heart Program

Recently, controversies have arisen concerning the association between nut intake and obesity. This study was performed to investigate the relationship between nut consumption and obesity among Iranian adults. In a cross-sectional survey, 9,660 randomly chosen adults aged ≥19 years were selected based on gender, age and their settlement distributions in three districts of central Iran in 2007. Nutritional behaviors including regular intake of walnuts, almonds, pistachios, hazelnuts and sunflower seed were assessed by validated 48-item-food-frequency questionnaire and a 24-h recall questionnaire. Using hierarchical logistic regression test, odds ratio (OR) 95% CI of obesity based on nut consumption was determined in an unadjusted and four adjusted models. The results showed a significant association between high nut consumption and lower prevalence of overweight or general obesity as well as abdominal obesity in women (p = 0.01 and p = 0.047, respectively), but not men. The frequency of nut consumption was associated with lower risk of overweight or general obesity [OR (95% CI) 0.57 (0.38-0.86)] and abdominal obesity [OR (95% CI) 0.51 (0.28-0.95)] only in women. After adjusting for gender, age and other potential confounders, the strength of the associations was blunted, but they were still significant. Frequent nuts and seeds consumption, particularly ≥1 time/day, had an inverse association with all classes of obesity among women.

Correlation of lipoprotein epoxide content to microvascular function after short‐term walnut intake (831.5)

We examined the relationship of walnut intake and walnut derived fatty acids on outcome measures of vascular health. Hypercholesterolemic postmenopausal women (n=36) were randomized to 4 weeks of 5 or 40g of daily walnut intake. Outcomes were measured after an overnight fast and 4 h after walnut intake, prior to and after the 4 week intervention. Forty g of walnut intake increased polyunsaturated fat intake, including n‐3 and n‐6 fatty acids. After 4 weeks of 40g of walnut intake, microvascular function as assessed by reactive hyperemia index (RHI) was significantly increased, while the augmentation index at a heart rate of 75, a measure of pulse wave reflection and arterial stiffness, was significantly decreased. No significant changes in vascular function were observed with 5g of walnut intake. Four weeks of 40g of walnut intake significantly reduced LDL levels, while increasing the lipoprotein content of alpha‐linolenic acid (ALA) and linoleic acid (LA). A number of ALA and LA oxylipins were increased within lipoproteins, particularly HDL. The changes in 12(13)‐epoxyoctadecamonoenoic acid (ρ = 0.78) and 15(16)‐epoxyoctadecadienoic acid (ρ=0.70) epoxides of LA and ALA, respectively, within HDL were significantly correlated to improvements in RHI. In conclusion, short‐term walnut intake increased microvascular function, possibly through changes to specific LA and ALA oxylipins within lipoproteins.

The effect of walnut (Juglans regiaL.) intake on improvement of blood lipid levels and vascular health: A meta-analysis

Purpose: Walnut is known to have unique favorable fatty acids, phytochemicals, and other nutrient profiles. As a result, there has been growing interest in evaluation of its health benefit related to cardiovascular disease (CVD). Although inverse associations of nut consumption and risk factors of cardiovascular disease have been reported in many epidemiological studies and qualitative reviews, few meta-analysis studies have been reported. This meta-analysis was conducted in order to evaluate the effect of a walnut-enhanced diet on CVD risk factors. Methods: We searched Pubmed, Cochrane, Science Direct, and KISS (Korean studies Information Service System) through July 2014. A random-effects meta-analysis was conducted on 17 trials reporting total cholesterol (TC), 14 trials reporting LDL cholesterol (LDL-C), 15 trials reporting HDL cholesterol (HDL-C), 17 trials reporting triglyceride (TG), and four trials reporting flow-mediated dilation (FMD). Results: In meta-analysis, intake of a walnut-enhanced diet resulted in significantly lowered TC, LDL-C, and TG by -0.124 mmol/l (95% CI, -0.209, -0.039; p = 0.004), -0.085 mmol/lL (95% CI, -0.167, -0.004; p = l0.039), and -0.080 mmol/l (95% CI, -0.155, -0.004; p = 0.039), respectively. The overall pooled estimate of the effect on FMD was +1.313% (95% CI, 0.744, 1.882, p = 0.000). HDL-C was not affected by walnut intake. No statistical heterogeneity was observed for any analysis. Results of funnel plots and Egger’s regression suggested a low likelihood of publication bias in all biomarkers (p ＞ 0.05). Conclusion: Findings of this meta-analysis provide consistent evidence that walnut-enhanced diet intake reduces the CVD risk factors.

Walnut Consumption Is Associated with Lower Risk of Type 2 Diabetes in Women

Walnuts are rich in polyunsaturated fatty acids and have been shown to improve various cardiometabolic risk factors. We aimed to investigate the association between walnut intake and incident type 2 diabetes in 2 large cohort studies: the Nurses' Health Study (NHS) and NHS II. We prospectively followed 58,063 women aged 52–77 y in NHS (1998–2008) and 79,893 women aged 35–52 y in NHS II (1999–2009) without diabetes, cardiovascular disease, or cancer at baseline. Consumption of walnuts and other nuts was assessed every 4 y using validated food frequency questionnaires. Selfreported type 2 diabetes was confirmed by a validated supplemental questionnaire. We documented a total of 5930 incident type 2 diabetes cases during 10 y of follow-up. In the multivariable-adjusted Cox proportional hazards model without body mass index (BMI), walnut consumption was associated with a lower risk of type 2 diabetes, and the HRs (95% CIs) for participants consuming 1–3 servings/mo (1 serving = 28 g), 1 serving/wk, and ≥2 servings/wk of walnuts were 0.93 (0.88–0.99), 0.81 (0.70–0.94), and 0.67 (0.54–0.82) compared with women who never/rarely consumed walnuts (P-trend < 0.001). Further adjustment for updated BMI slightly attenuated the association and the HRs (95% CIs) were 0.96 (0.90–1.02), 0.87 (0.75–1.01), and 0.76 (0.62–0.94), respectively (P-trend = 0.002). The consumption of total nuts (P-trend < 0.001) and other tree nuts (P-trend = 0.03) was also inversely associated with risk of type 2 diabetes, and the associations were largely explained by BMI. Our results suggest that higher walnut consumption is associated with a significantly lower risk of type 2 diabetes in women.

Atheroprotective effect of dietary walnut intake in ApoE-deficient mice: Involvement of lipids and coagulation factors

IntroductionConsumption of n-3 polyunsaturated fatty acids (PUFA) and antioxidant polyphenols is considered to decline the risk of cardiovascular disease. Materials and MethodsTo provide an explanation for this cardioprotective effect, we performed an intervention study with proatherogenic Apoe−/− mice which were fed during eight weeks with a high fat diet supplemented with either walnuts (rich in n-3 PUFA and antioxidant compounds), walnut oil (with n-3 PUFA only) or sunflower oil as a control (12 mice per group). ResultsFeeding walnuts, but not walnut oil, caused a 55% reduction in atherosclerotic plaque development in the aortic arch in comparison to the control diet. This was associated with reduced staining of plaques for CD36, a scavenger receptor expressed by macrophages. Feeding mice with walnuts also lowered plasma levels of triglycerides, cholesterol and prothrombin with 36%, 23% and 21 %, respectively, compared to control diet. In addition, accumulation of lipids in the liver was decreased, while plasma antioxidant capacity was increased. On the other hand, feeding mice with walnut oil did not provoke significant changes in these parameters in comparison to the control diet. Platelet activation and thrombus formation under flow remained unchanged with either diet. ConclusionsIn Apoe−/− mice on high fat diet, intake of dietary walnut (but not walnut oil) beneficially influences lipid metabolism and atherosclerotic plaque development, with no more than limited effects on platelet and coagulation function.

Effects of Walnuts on Endothelial Function in Overweight Adults with Visceral Obesity: A Randomized, Controlled, Crossover Trial

Objectives: Metabolic syndrome is a precursor of diabetes and cardiovascular disease (CVD). Walnut ingestion has been shown to reduce CVD risk indices in diabetes. This randomized controlled crossover trial was performed to investigate the effects of daily walnut consumption on endothelial function and other biomarkers of cardiac risk in a population of overweight individuals with visceral adiposity.Methods: Forty-six overweight adults (average age, 57.4 years; 28 women, 18 men) with elevated waist circumference and 1 or more additional signs of metabolic syndrome were randomly assigned to two 8-week sequences of walnut-enriched ad libitum diet and ad libitum diet without walnuts, which were separated by a 4-week washout period. The primary outcome measure was the change in flow-mediated vasodilation (FMD) of the brachial artery. Secondary measures included serum lipid panel, fasting glucose and insulin, Homeostasis Model Assessment–Insulin Resistance values, blood pressure, and anthropometric measures.Results: FMD improved significantly from baseline when subjects consumed a walnut-enriched diet as compared with the control diet (1.4% ± 2.4% versus 0.3% ± 1.5%; p = 0.019). Beneficial trends in systolic blood pressure reduction were seen, and maintenance of the baseline anthropometric values was also observed. Other measures were unaltered.Conclusion: Daily ingestion of 56 g of walnuts improves endothelial function in overweight adults with visceral adiposity. The addition of walnuts to the diet does not lead to weight gain. Further study of the potential role of walnut intake in diabetes and CVD prevention is warranted.

Effects of Walnuts (Juglans regia) on Learning and Memory Functions

Walnut has been regarded as a health food that is delicious and nutritious. Both preventive and therapeutic effects of walnut are well documented. Walnuts are rich in omega-3 fatty acids that are reported to have beneficial effects on brain function. The present work was designed to evaluate the effects of walnuts on learning and memory in male rats. The effect of oral intake of walnut was also monitored on food intake. Walnut was given orally to rats for a period of 28days. Memory function in rats was assessed by elevated plus maze (EPM) and radial arm maze (RAM). A significant improvement in learning and memory of walnut treated rats compared to controls was observed. Walnut treated rats also exhibited a significant decrease in food intake while the change in growth rate (in terms of percentage) remained comparable between the two groups. Analysis of brain monoamines exhibited enhanced serotonergic levels in rat brain following oral intake of walnuts. The findings suggest that walnut may exert its hypophagic and nootropic actions via an enhancement of brain 5-HT metabolism.

Walnut oil increases cholesterol efflux through inhibition of stearoyl CoA desaturase 1 in THP-1 macrophage-derived foam cells

BackgroundWalnuts significantly decrease total and low-density lipoprotein cholesterol in normo- and hypercholesterolemic individuals. No study to date has evaluated the effects of walnuts on cholesterol efflux, the initial step in reverse cholesterol transport, in macrophage-derived foam cells (MDFC). The present study was conducted to investigate the mechanisms by which walnut oil affects cholesterol efflux.MethodsThe extract of English walnuts (walnut oil) was dissolved in DMSO and applied to cultured THP-1 MDFC cells (0.5 mg/mL). THP-1 MDFC also were treated with human sera (10%, v:v) taken from subjects in a walnut feeding study. Cholesterol efflux was examined by liquid scintillation counting. Changes in gene expression were quantified by real time PCR.ResultsWalnut oil treatment significantly increased cholesterol efflux through decreasing the expression of the lipogenic enzyme stearoyl CoA desaturase 1 (SCD1) in MDFC. Alpha-linolenic acid (ALA), the major n-3 polyunsaturated fatty acids found in walnuts, recaptured SCD1 reduction in MDFC, a mechanism mediated through activation of nuclear receptor farnesoid-X-receptor (FXR). Postprandial serum treatment also increased cholesterol efflux in MDFC. When categorized by baseline C-reactive protein (CRP; cut point of 2 mg/L), subjects in the lower CRP sub-group benefited more from dietary intervention, including a more increase in cholesterol efflux, a greater reduction in SCD1, and a blunted postprandial lipemia.ConclusionIn conclusion, walnut oil contains bioactive molecules that significantly improve cholesterol efflux in MDFC. However, the beneficial effects of walnut intake may be reduced by the presence of a pro-inflammatory state.Trial RegistrationClinicalTrials.gov: NCT00938340

Body mass interacts with fat quality to determine the postprandial lipoprotein response in healthy young adults

Background and aimsPostprandial lipemia predicts the evolution of cardiovascular disease. Obesity is associated with an increase in the magnitude of postprandial lipemia. Our objective was to evaluate the influence of body mass index (BMI) on the effects of acute ingestion of different types of fat on the postprandial lipemic response. Methods and resultsTwenty-one healthy men followed a 4-week baseline diet and then consumed three fat-loaded meals that included 1g fat/kg body wt (65%fat) according to a randomized crossover design. The compositions of the three meals were olive oil meal (22% saturated fatty acids (SFA), 38% monounsaturated fatty acids (MUFA), 4% polyunsaturated fatty acids (PUFA)); butter meal (35% SFA, 22% MUFA, 4% PUFA); walnuts meal (20% SFA, 24% MUFA, 16% PUFA, and 4% α-linolenic acid). Higher-weight (HW) subjects (BMI greater than the median 26.18kg/m2, n=11) presented higher incremental area under the curve (iAUC) for triglycerides (TG), both in large- and small-TG rich lipoproteins (TRL) than lower-weight (LW) subjects (BMI<26.18kg/m2, n=10) (p<0.05), and a similar trend for plasma TG (p=0.084). Moreover, HW subjects presented higher concentrations for small TRL-cholesterol and small TRL-TG in different timepoints of the postprandial lipemia after the intake of enriched walnuts or butter meals compared with the olive oil-enriched meal (p<0.05) No significant differences were observed between the three types of meals in the postprandial response of LW subjects. ConclusionHW subjects present a greater postprandial response than LW subjects, and they benefit from the consumption of monounsaturated fatty acids from olive oil, to lower their levels of TRL particles during the postprandial state.

Chronic and acute effects of walnuts on antioxidant capacity and nutritional status in humans: a randomized, cross-over pilot study

BackgroundCompared with other common plant foods, walnuts (Juglans regia) are consistently ranked among the highest in antioxidant capacity. In vitro, walnut polyphenols inhibit plasma and LDL oxidation, while in animal models they lower biomarkers of oxidative stress and raise antioxidant capacity. A limited number of human feeding trials indicate that walnuts improve some measures of antioxidant status, but not others.MethodsA 19 wk, randomized crossover trial was conducted in 21 generally healthy men and postmenopausal women ≥50 y to study the dose-response effects of walnut intake on biomarkers of antioxidant activity, oxidative stress, and nutrient status. Subjects were randomized to receive either 21 or 42 g raw walnuts/d during each 6 wk intervention phase with a 6 wk washout between phases. Subjects were instructed to consume their usual diet, but refrain from eating any other tree nuts, seeds, peanuts, or ellagitannin-rich foods during the entire study, and other polyphenol-rich foods for 2 d prior to each study visit.ResultsCompared to baseline levels, red blood cell (RBC) linoleic acid and plasma pyridoxal phosphate (PLP) were significantly higher after 6 wk with 42 g/d walnuts (P < 0.05 for both). Overall, changes in plasma total thiols, and other antioxidant biomarkers, were not significant with either walnut dose. However, when compared to fasting levels, plasma total thiols were elevated within 1 h of walnut consumption with both doses during the baseline and end visits for each intervention phase (P < 0.05 for all). Despite the observed increase in RBC linoleic and linolenic acids associated with walnut consumption, this substrate for lipid peroxidation only minimally affected malondialdehyde (MDA) and antioxidant capacity. The proportional changes in MDA and Oxygen Radical Absorbance Capacity (ORAC) were consistent with a dose-response effect, although no significant within- or between-group differences were observed for these measures.ConclusionsWalnut consumption did not significantly change the plasma antioxidant capacity of healthy, well-nourished older adults in this pilot study. However, improvements in linoleic acid and pyridoxal phosphate were observed with chronic consumption, while total plasma thiols were enhanced acutely. Future studies investigating the antioxidant effects of walnuts in humans are warranted, but should include either a larger sample size or a controlled feeding intervention.Trial RegistrationClinicalTrials.gov: NCT00626691

Effect of whole walnuts and walnut-skin extracts on oxidant status in mice

Objective To evaluate the effect of the intake of whole walnuts and walnut fractions on the oxidant status in mice. Methods Thirty-six C57BL/6J male mice were randomized to be fed one of three diets: 1) a standard diet (control group), 2) a standard diet with 10% of whole walnuts (walnut-diet group), or 3) a standard diet with 2% of walnut skins (walnut-skin-diet group) for 8 wk. The plasma antioxidant capacity was measured by oxygen radical-absorbance capacity and plasma ferric-reducing antioxidant potential. Conjugated diene formation and reduced glutathione levels were also analyzed. Results We observed no changes in plasma oxidation capability between the walnut and walnut-skin groups with the exception of conjugated dienes. Plasma total antioxidant capacity and the ratio between reduced and oxidized forms of glutathione were lower in the walnut and walnut-skin groups than in the control group. Conclusion The decrease in the antioxidant burden observed in enzymatic and non-enzymatic antioxidant systems after sustained consumption of a whole-walnut or a walnut-skin diet in mice may be related to the plasma oxidation capability being maintained in the groups consuming the walnut diets.

English walnuts (Juglans regia L.) improve antioxidant capacity in humans

The consumption of English walnuts (Juglans regia L.) promotes cardiovascular health, in part due to its favorable effect on serum lipids. Walnut polyphenols, including ellagitannins (ET) may also contribute to this benefit. To determine whether consuming walnuts in amounts readily incorporated into the diet (0.75 and 1.50 oz) has a dose‐response effect on plasma antioxidant capacity, we conducted a randomized, crossover study with a 1 wk run‐in period, 6 wk interventions with each walnut dose, and a 6 wk washout period between these tests in 20 healthy, non‐smoking adults ≥50 y. Subjects followed a low ET diet during the entire 19 wk study, and a low polyphenol diet for 2 d prior to each visit. Walnut intake tended to increase selected measures of plasma antioxidant capacity in a dose‐dependent manner with a higher proportion of responders in the 1.50 vs. 0.75 oz group, particularly in women. These data suggest that walnuts may modestly improve antioxidant capacity in humans, revealing another potential mechanism to further support the FDA qualified health claim that the regular consumption of walnuts decreases the risk of heart disease. (Supported by USDA and California Walnut Commission)

The effect of walnut intake on factors related to prostate and vascular health in older men.

BackgroundTocopherols may protect against prostate cancer and cardiovascular disease (CVD).MethodsWe assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). Subjects (n = 21) consumed (in random order) their usual diet +/- a walnut supplement (75 g/d) that was isocalorically incorporated in their habitual diets. Prior to the supplement study, 5 fasted subjects participated in an acute timecourse experiment and had blood taken at baseline and 1, 2, 4, and 8 h after consuming walnuts (75 g).ResultsDuring the timecourse experiment, triglycerides peaked at 4 h, and gamma-tocopherol (γ-T) increased from 4 to 8 h. Triglyceride – normalized γ-T was two-fold higher (P = 0.01) after 8 versus 4 h. In the supplement study, change from baseline was +0.83 ± 0.52 μmol/L for γ-T, -2.65 ± 1.30 μmol/L for alpha-tocopherol (α-T) and -3.49 ± 1.99 for the tocopherol ratio (α-T: γ-T). A linear mixed model showed that, although PSA did not change, the ratio of free PSA:total PSA increased and approached significance (P = 0.07). The α-T: γ-T ratio decreased significantly (P = 0.01), partly reflecting an increase in serum γ-T, which approached significance (P = 0.08).ConclusionThe significant decrease in the α-T: γ-T ratio with an increase in serum γ-T and a trend towards an increase in the ratio of free PSA:total PSA following the 8-week supplement study suggest that walnuts may improve biomarkers of prostate and vascular status.

Consumption of Restructured Meat Products with Added Walnuts Has a Cholesterol-Lowering Effect in Subjects at High Cardiovascular Risk: A Randomised, Crossover, Placebo-Controlled Study

Background: Diet and lifestyle are modifiable factors involved in the development and prevention of non-communicable diseases, including cardiovascular disease. Nut consumption, particularly walnut intake, has been inversely related to incident coronary heart disease (CHD) in observational studies and to improved lipid profiles in short-term feeding trials.Objective: To assess the potential functional effect associated with the regular consumption of walnut-enriched restructured meat products in subjects at risk for cardiovascular disease (CVD).Design: A crossover single-dose bioavailability study (n = 3) using γ-tocopherol as exposure marker and a crossover unblinded dietary intervention study (5 weeks) in subjects at risk (n = 25). Dietary intervention consisted of regular consumption of the meat product, with or without walnuts, five times per week for five weeks with a 1-month washout in between. Overnight fasting blood samples were collected on days 0, 12, 21, 28 and 35, coinciding with blood pressure and body weight recordings. Participants were asked to complete a diet record throughout the study. The functional effects were assessed using clinically relevant and related biomarkers of CHD: serum total, HDL and LDL cholesterol, triacylglycerols, homocysteine, vitamins B6 and B12, folic acid, α-tocopherol and platelet function test (obturation time).Results: The regular consumption of walnut-enriched meat products compared with that of the restructured meat products without added walnuts provokes a decrease in total cholesterol of 6.8 mg/dl (CI95%: −12.8, −0.85). Compared to baseline (mixed diet), meat products with walnuts decreased total cholesterol (−10.7 mg/dl, CI95%: −17.1, −4.2), LDL cholesterol (−7.6 mg/dl, CI95%: −2.2, −13.0) and body weight (−0.5 kg, CI95%: −0.1, −0.9) and increased γ-tocopherol (8.9 mg/dl, CI95%: 1.0, 16.8).Conclusions: The restructured meat products with added walnuts supplied in this study can be considered functional foods for subjects at high risk for CVD, as their regular consumption provokes a reduction in total cholesterol of 4.5% with respect to baseline values (mixed diet) and 3% with respect to the restructured meat without walnuts.

The effect of walnut intake on factors related to prostate and vascular health in men at increased risk for prostate cancer

Tocopherols may protect against prostate cancer. We conducted a free-living feeding study to assess the effect of walnuts, a tocopherol-rich food, on markers of prostate and vascular health in men at risk for prostate cancer. We examined serum tocopherol levels, lipids, selected hormones, PSA, food records and urinary symptoms data. Subjects (n=21) were randomized to an 8-week walnut diet (75 g/d) or their usual diet (control) and switched to the other diet for the second 8-week period following a 2-week washout. Fasted subjects had blood drawn at baseline and at the end of each diet period. All analyses were adjusted for weight, and the tocopherol analyses were also adjusted for age and lipids. No sequence effects were detected. At baseline, average serum concentrations were 193 mg/dl (SD=28.2) for total cholesterol, 102 mg/dl (SD=48.5) for triglycerides, 19.2 % (SD=8.53) for percent free PSA (PFP), 139 ng/ml (SD=40.5) for IGF-1, 29.3 μM (SD=10.0) for α-tocopherol (αT), 4.14 μM (SD=1.99) for γ-tocopherol (γ T) and 11.0 (SD=9.91) for the tocopherol ratio (αT: γ T). A change score was used to measure differences in concentrations between baseline and the diet periods. During the walnut diet, decreasing trends were seen in the mean serum concentrations of several variables, including αT: γ T (Δ =−3.46), total cholesterol (Δ =−6.00), triglycerides (Δ =−6.00) and PFP (Δ =−0.40%). In addition, a decreasing trend in mean serum IGF-1 was seen when comparing the diets (Δ =−8.00). Walnut consumption may thus improve markers associated with prostate cancer and cardiovascular disease risks. Funded by the California Walnut Commission.