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Research Nut: Mixed Nuts

Frequent nut consumption and decreased risk of cholecystectomy in women

Tsai, C-J., M.F. Leitzmann, F.B. Hu, W.C. Willett, E.L. Giovannucci, 2004.  Frequent nut consumption and decreased risk of cholecystectomy in women. Am J Clin Nutr. 80:76-81.

Background: Gallstone disease is a major source of morbidity in the developed countries. Nuts are rich in several compounds that may protect against gallstone disease. Objective: The association between nut intake and cholecystectomy was examined in a large cohort of women. Design: We prospectively studied nut (peanuts, other nuts, and peanut butter) consumption in relation to the risk of cholecystectomy in a cohort of 80 718 women from the Nurses’ Health Study who were 30–55 y old in 1980 and had no history of gallstone disease. As part of the Nurses’ Health Study, the women reported on questionnaires mailed to them every 2 y both their consumption of nuts and whether they had undergone cholecystectomy. The women were followed through 2000. Results: During 1 393 256 person-years of follow-up from 1980 to 2000, we documented 7831 cholecystectomies. After adjustment for age and other known or suspected risk factors, women who consumed ≥5 units of nuts (1 unit = 1 oz or 28.6 g nuts)/wk (frequent consumption) had a significantly lower risk of cholecystectomy (relative risk: 0.75; 95% CI: 0.66, 0.85; P for trend < 0.0001) than did women who never ate nuts or who ate <1 unit/mo (rare consumption). Further adjustment for fat consumption (saturated fat, trans fat, polyunsaturated fat, and monounsaturated fat) did not materially alter the relation. In analyses examining consumption of peanuts and other nuts separately, both were associated with a lower risk of cholecystectomy. Conclusion: In women, frequent nut consumption is associated with a reduced risk of cholecystectomy.

Magnesium intake and risk of type 2 diabetes in men and women

Lopez-Ridaura, R., W.C. Willett, E.B. Rimm, S. Liu, M.J. Stampfer, J.E. Manson, F.B. Hu, 2004.  Magnesium intake and risk of type 2 diabetes in men and women. Diabetes Care. 27(1): 134-40.

Objective: To examine the association between magnesium intake and risk of type 2 diabetes. Research Design and Methods: We followed 85,060 women and 42,872 men who had no history of diabetes, cardiovascular disease, or cancer at baseline. Magnesium intake was evaluated using a validated food frequency questionnaire every 2–4 years. After 18 years of follow-up in women and 12 years in men, we documented 4,085 and 1,333 incident cases of type 2 diabetes, respectively. Results:After adjusting for age, BMI, physical activity, family history of diabetes, smoking, alcohol consumption, and history of hypertension and hypercholesterolemia at baseline, the relative risk (RR) of type 2 diabetes was 0.66 (95% CI 0.60–0.73; P for trend<0.001) in women and 0.67 (0.56–0.80; P for trend <0.001) in men, comparing the highest with the lowest quintile of total magnesium intake. The RRs remained significant after additional adjustment for dietary variables, including glycemic load, polyunsaturated fat, trans fat, cereal fiber, and processed meat in the multivariate models. The inverse association persisted in subgroup analyses according to BMI, physical activity, and family history of diabetes. Conclusions: Our findings suggest a significant inverse association between magnesium intake and diabetes risk. This study supports the dietary recommendation to increase consumption of major food sources of magnesium, such as whole grains, nuts, and green leafy vegetables.

Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome

Esposito, K., R. Marfella, M. Ciotola, C. Di Palo, F. Giugliano, G. Giugliano, M. D’Armiento, F. D’Andrea, D. Giugliano, 2004.  Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome. JAMA. 292:1440-6.

Context The metabolic syndrome has been identified as a target for dietary therapies to reduce risk of cardiovascular disease; however, the role of diet in the etiology of the metabolic syndrome is poorly understood. Objective To assess the effect of a Mediterranean-style diet on endothelial function and vascular inflammatory markers in patients with the metabolic syndrome. Design, Setting, and Patients Randomized, single-blind trial conducted from June 2001 to January 2004 at a university hospital in Italy among 180 patients (99 men and 81 women) with the metabolic syndrome, as defined by the Adult Treatment Panel III. Interventions Patients in the intervention group (n=90) were instructed to follow a Mediterranean-style diet and received detailed advice about how to increase daily consumption of whole grains, fruits, vegetables, nuts, and olive oil; patients in the control group (n=90) followed a prudent diet (carbohydrates, 50%-60%; proteins, 15%-20%; total fat, <30%). Main Outcome Measures Nutrient intake; endothelial function score as a measure of blood pressure and platelet aggregation response to L-arginine; lipid and glucose parameters; insulin sensitivity; and circulating levels of high-sensitivity C-reactive protein (hs-CRP) and interleukins 6 (IL-6), 7 (IL-7), and 18 (IL-18). Results After 2 years, patients following the Mediterranean-style diet consumed more foods rich in monounsaturated fat, polyunsaturated fat, and fiber and had a lower ratio of omega-6 to omega-3 fatty acids. Total fruit, vegetable, and nuts intake (274 g/d), whole grain intake (103 g/d), and olive oil consumption (8 g/d) were also significantly higher in the intervention group (P<.001). The level of physical activity increased in both groups by approximately 60%, without difference between groups (P=.22). Mean (SD) body weight decreased more in patients in the intervention group (−4.0 [1.1] kg) than in those in the control group (−1.2 [0.6] kg) (P<.001). Compared with patients consuming the control diet, patients consuming the intervention diet had significantly reduced serum concentrations of hs-CRP (P=.01), IL-6 (P=.04), IL-7 (P=0.4), and IL-18 (P=0.3), as well as decreased insulin resistance (P<.001). Endothelial function score improved in the intervention group (mean [SD] change, +1.9 [0.6]; P<.001) but remained stable in the control group (+0.2 [0.2]; P=.33). At 2 years of follow-up, 40 patients in the intervention group still had features of the metabolic syndrome, compared with 78 patients in the control group (P<.001). Conclusion A Mediterranean-style diet might be effective in reducing the prevalence of the metabolic syndrome and its associated cardiovascular risk.

Association of nut and seed intake with colorectal cancer risk in the European prospective investigation into cancer and nutrition.

Jenab, M., et al., 2004.  Association of nut and seed intake with colorectal cancer risk in the European prospective investigation into cancer and nutrition. Cancer Epidemiol Biomarkers Prev. 13(10):1595-603.

A link between unsaturated fatty acids or phytonutrients and reduced risk of colorectal cancer has been suggested. However, the effects of higher intake of dietary sources of these nutrients, such as the nuts and seeds food group, are less clear. The objective of this study was to determine the effects of nut and seed intake on colorectal cancer risk within the European Prospective Investigation into Cancer and Nutrition study, a large prospective cohort study involving 10European countries. Total nut and seed intake was determined from country-specific dietary questionnaires. The data set included 478,040 subjects (141,988 men, 336,052 women) with a total of 855 (327 men, 528 women) colon and 474 (215 men, 259 women) rectal cancer cases. A multivariate Cox proportional hazards model, stratified by center and controlled for fruit intake, dietary fiber, energy, height, weight, sex, age, physical activity, and smoking, was used. The data show no association between higher intake of nuts and seeds and risk of colorectal, colon, and rectal cancers in men and women combined, but a significant inverse association was observed in subgroup analyses for colon cancer in women at the highest (>6.2 g/d) versus the lowest (nonconsumers; hazard ratio, 0.69; 95% confidence interval, 0.50-0.95) category of intake and for the linear effect of log-transformed intake (hazard ratio, 0.89; 95% confidence interval, 0.80-0.98), with no associations in men. It is not evident from this data why there may be a stronger association in women or why it may be limited to the colon, suggesting that much further research is necessary.

Vitamin K content of nuts and fruits in the US diet.

Dismore, M.L.,  D.B. Haytowitz, S.E. Gebhardt, J.W. Peterson, S.L. Booth, 2003. Vitamin K content of nuts and fruits in the US diet. J Am Diet Assoc. 103:1650-1652.

Assessment of vitamin K dietary intakes has been limited by incomplete vitamin K food composition data for the US food supply. The phylloquinone (vitamin K1) concentrations of nuts (n=76) and fruits (n=215) were determined by high-performance liquid chromatography. Each sample represented a composite of units obtained from 12 to 24 outlets, which provided geographic representation of the US food supply. With the exception of pine nuts and cashews, which contain 53.9 and 34.8 µg of phylloquinone per 100 g of nut, respectively, nuts are not important dietary sources of vitamin K. Similarly, most fruits are not important sources of vitamin K, with the exception of some berries, green fruits, and prunes. Menu planning for patients on warfarin can include a healthy diet including fruits and nuts without compromising the stability of their oral anticoagulation therapy.

The natural history of food allergy.

Wood, R.A., 2003. The natural history of food allergy. Pediatrics. 111:1631–1637.

The natural history of food allergy refers to the development of food sensitivities as well as the possible loss of the same food sensitivities over time. Most food allergy is acquired in the first 1 to 2 years of life, whereas the loss of food allergy is a far more variable process, depending on both the individual child and the specific food allergy. For example, whereas most milk allergy is outgrown over time, most allergies to peanuts and tree nuts are never lost. In addition, whereas some children may lose their milk allergy in a matter of months, the process may take as long as 8 or 10 years in other children. This review provides an overview of the natural history of food allergy and provides specific information on the natural course of the most common childhood food allergies.

Tree nut allergens.

Roux, K.H., S.S. Teuber, S.K. Sathe, 2003. Tree nut allergens. Int Arch Allergy Immunol. 131:234–244.

Allergic reactions to tree nuts can be serious and life threatening. Considerable research has been conducted in recent years in an attempt to characterize those allergens that are most responsible for allergy sensitization and triggering. Both native and recombinant nut allergens have been identified and characterized and, for some, the IgE-reactive epitopes described. Some allergens, such as lipid transfer proteins, profilins, and members of the Bet v 1-related family, represent minor constituents in tree nuts. These allergens are frequently cross-reactive with other food and pollen homologues, and are considered panallergens. Others, such as legumins, vicilins, and 2S albumins, represent major seed storage protein constituents of the nuts. The allergenic tree nuts discussed in this review include those most commonly responsible for allergic reactions such as hazelnut, walnut, cashew, and almond as well as those less frequently associated with allergies including pecan, chestnut, Brazil nut, pine nut, macadamia nut, pistachio, coconut, Nangai nut, and acorn.

Tree nut allergy.

Teuber, S.S., S.S. Comstock, S.K. Sathe, K.H. Roux, 2003. Tree nut allergy. Current Allergy and Asthma Reports. 3:54–61.

Tree nuts are clinically associated with severe immunoglobulin E–mediated systemic allergic reactions independent of pollen allergy and with reactions that are usually confined to the oral mucosa in patients with immunoglobulin E directed toward cross-reacting pollen allergens. The latter reactions can progress to severe and life-threatening episodes in some patients. Many patients with severe tree nut allergy are co-sensitized to peanut. Clinical studies on cross-reactivity between the tree nuts are few in number, but based on reports to date, avoidance of the other tree nuts once sensitivity is diagnosed appears prudent unless specific challenges are performed to ensure clinical tolerance. Even then, great care must be taken to avoid cross-contamination. As with other severe food allergies, a recurrent problem in clinical management is the failure of physicians to prescribe self-injectable epinephrine to patients who are at risk of anaphylaxis.

Immunological analysis of allergenic cross-reactivity between peanut and tree nuts.

de Leon, M.P., I.N. Glaspole, A C. Drew, J.M. Rolland, R.E. O’Hehir, C. Suphioglu, 2003. Immunological analysis of allergenic cross-reactivity between peanut and tree nuts. Clin Exp Allergy. 33:1273–1280.

Background: Peanut and tree nut allergy is characterized by a high frequency of life-threatening anaphylactic reactions and typically lifelong persistence. Peanut allergy is more common than tree nut allergy, but many subjects develop hypersensitivity to both peanuts and tree nuts. Whether this is due to the presence of cross-reactive allergens remains unknown. Objective: The aim of this study was to investigate the presence of allergenic cross-reactivity between peanut and tree nuts. Methods Western blotting and ELISA were performed using sera from subjects with or without peanut and tree nut allergy to assess immunoglobulin E (IgE) reactivity to peanut and tree nut extracts. Inhibition ELISA studies were conducted to assess the presence of allergenic cross-reactivity between peanut and tree nuts. Results: Western blot and ELISA results showed IgE reactivity to peanut, almond, Brazil nut, hazelnut and cashew nut for peanut- and tree nut-allergic subject sera. Raw and roasted peanut and tree nut extracts showed similar IgE reactivities. Inhibition ELISA showed that pre-incubation of sera with almond, Brazil nut or hazelnut extracts resulted in a decrease in IgE binding to peanut extract, indicating allergenic cross-reactivity. Pre-incubation of sera with cashew nut extract did not cause any inhibition. Conclusion: These results show that multiple peanut and tree nut sensitivities observed in allergic subjects may be due to cross-reactive B cell epitopes present in different peanut and tree nut allergens. The plant taxonomic classification of peanut and tree nuts does not appear to predict allergenic cross-reactivity.

Interpretation of tests for nut allergy in one thousand patients, in relation to allergy or tolerance.

Clark A.T., P.W. Ewan, 2003. Interpretation of tests for nut allergy in one thousand patients, in relation to allergy or tolerance. Clin Exp Allergy. 33(8):1041-1045.

BACKGROUND: Peanut and tree nut allergy are common, increasing in prevalence and the commonest food cause of anaphylaxis. In the USA, 7.8% are sensitized (have nut-specific IgE), but not all those sensitized are allergic. Lack of data makes interpretation of tests for nut-specific IgE difficult. OBJECTIVES: This is the first study to investigate the clinical significance of test results for peanut and tree nut allergy in allergic or tolerant patients. Findings are related to the severity of the allergy. METHOD: An observational study of 1000 children and adults allergic to at least one nut. History of reactions (severity graded) or tolerance to up to five nuts was obtained and skin prick test (SPT)/serum-specific IgE (CAP) performed. RESULTS: There was no correlation between SPT size and graded severity of worst reaction for all nuts combined or for peanut, hazelnut, almond and walnut. For CAP, there was no correlation for all nuts. Where patients tolerated a nut, 43% had positive SPT of 3-7 mm and 3% ≥ 8 mm. For CAP, 35% were positive (0.35-14.99 kU/L) and 5% ≥ 15 kU/L. In SPT range 3-7 mm, 54% were allergic and 46% were tolerant. There was poor concordance between SPT and CAP (66%). Of patients with a clear nut-allergic history, only 0.5% had negative SPT, but 22% negative CAP. CONCLUSIONS: Magnitude of SPT or CAP does not predict clinical severity, with no difference between minor urticaria and anaphylaxis. SPT is more reliable than CAP in confirming allergy. Forty-six per cent of those tolerant to a nut have positive tests > or = 3 mm (sensitized but not allergic). One cannot predict clinical reactivity from results in a wide ‘grey area’ of SPT 3-7 mm; 22% of negative CAPs are falsely reassuring and 40% of positive CAPs are misleading. This emphasizes the importance of the history. Understanding this is essential for accurate diagnosis. Patients with SPT > or = 8 mm and CAP ≥ 15 kU/L were rarely tolerant so these levels are almost always (in ≥ 95%) diagnostic.