Tree nut and peanut consumption in relation to chronic and metabolic diseases including allergy

Meta-analysis of the association between nut consumption and the risks of cancer incidence and cancer-specific mortality

Previous studies have indicated a correlation between nut intake and cancer risk in humans. This meta-analysis aimed to determine the relationship between nut consumption and the risks of cancer incidence and mortality. The PubMed, Embase, and Web of Science databases were searched up to August 2019. Relative risks and 95% confidence intervals were calculated using random-effects and fixed-effects models. We included 38 studies on nut consumption and cancer risk and 9 studies on cancer-specific mortality. Compared with no nut intake, nut intake was associated with a lower cancer risk (Relative Risk=0.90; 95% confidence interval, 0.86–0.94). Inverse associations were observed with colorectal cancer, gastric cancer, pancreatic cancer, and lung cancer in subgroup analyses. Tree nut consumption was found to reduce cancer risk (Relative Risk=0.88; 95% confidence interval, 0.79–0.99). Dose-response curves suggested that protective benefits against cancer increased with increased nut intake (P=0.005, P-nonlinearity=0.0414). An inverse correlation with cancer-specific mortality (Odd Ratio=0.90; 95% confidence interval, 0.88–0.92) was observed. In conclusion, nut consumption is inversely associated with the risks of cancer incidence and mortality; a higher intake is significantly associated with a lower cancer risk.

Can Nuts Mitigate Malnutrition in Older Adults? A Conceptual Framework

The proportion of adults aged over 60 years in the world is expected to reach 20% by the year 2050. Ageing is associated with several physiological changes that increase the risk of malnutrition among this population. Malnutrition is characterized by deficiencies or insufficiencies of macro- and micronutrients. Malnutrition has detrimental effects on the health, wellbeing, and quality of life in older adults. Nuts are rich in energy, unsaturated fats, and protein, as well as other nutrients that provide a range of health benefits. While the effects of nuts on overnutrition have been studied extensively, very few studies have been specifically designed to understand the role of nuts in mitigating undernutrition in the elderly. Therefore, this review explores the potential role of nuts in improving the nutritional status of older adults who are at risk of undernutrition. Several properties of whole nuts, some of which appear important for addressing overnutrition, (e.g., hardness, lower-than-expected nutrient availability, satiety-enhancing effects) may limit their effectiveness as a food to combat undernutrition. However, we propose that modifications such as transforming the physical form of nuts, addressing the timing of nut ingestion, and introducing variety may overcome these barriers. This review also discusses the feasibility of using nuts to prevent and reverse undernutrition among older adults. We conclude with a recommendation to conduct clinical studies in the future to test this conceptual framework.

Perceptions and Knowledge of Nuts amongst Health Professionals in New Zealand

Despite their nutritional value, population-level nut consumption remains low. Studies suggest that individuals would eat more nuts on their doctor’s advice, making health professionals potentially important for promoting nut consumption. This cross-sectional study aimed to examine the perceptions and knowledge of nuts and the predictors of nut promotion among health professionals in New Zealand. Dietitians, general practitioners (GPs), and practice nurses were identified from the Electoral Roll and invited to complete a questionnaire (n = 318, 292, and 149 respondents respectively). Over one-fifth of GPs and practice nurses believed that eating nuts could increase blood cholesterol concentrations and cause weight gain. The most common perceptions overall were that nuts are healthy; high in protein, fat, and calories; and are satiating. Nut consumption was recommended for reasons relating to these perceptions and because of nuts’ selenium content. Conversely, reasons for suggesting the consumption of fewer nuts included that they were high in calories and fat, would cause weight gain, and concerns regarding allergies and cost. All groups of health professionals were more likely to promote nut consumption if they perceived nuts to reduce the risk of diabetes (all p ≤ 0.034). Education could improve health professionals’ knowledge regarding the effects of nut consumption on blood cholesterol and body weight, alongside other health benefits, which should improve the advice given to patients and may thereby increase nut consumption.

Tree nuts and peanuts as components of a healthy diet

Nuts have been part of the diet for thousands of years. In 2003, a Qualified Health Claim was approved, stating that eating 1.5 oz (42 g) of nuts per day may reduce the risk of heart disease. Usual intakes fall short of this recommendation. About one-third of Americans report consuming nuts (tree nuts or peanuts) on any one day. Seven percent of Europeans report eating nuts, but the amount eaten by European nut consumers (31 g/d) is larger than that of Americans (21 g/d). Nuts are an excellent source of vitamin E and magnesium. Individuals consuming nuts also have higher intakes of folate, beta-carotene, vitamin K, lutein+zeaxanthin, phosphorus, copper, selenium, potassium, and zinc per 1000 kcal. Regular nut consumption increases total energy intake by 250 kcal/d (1.05 MJ/d), but the body weight of nut consumers is not greater than that of nonconsumers. Nuts are an excellent source of phytochemicals (phyotsterols, phenolic acids, flavonoids, stilbenes, and carotenoids). The total phenolic constituents probably contribute to the total antioxidant capacity of nuts, which is comparable to broccoli and tomatoes. To improve guidance on the use of nuts in the diet, the position of nuts in typical food patterns needs to be addressed. The 2005 MyPyramid includes nuts in the meat and beans group. Yet, nuts are rarely consumed as meat substitutes. Because approximately 60% of the nuts consumed in the U.S. are eaten as snacks, emphasizing their use as a healthy snack may be more effective than inclusion within a food group.

Possible benefit of nuts in type 2 diabetes

Nuts, including peanuts, are now recognized as having the potential to improve the blood lipid profile and, in cohort studies, nut consumption has been associated with a reduced risk of coronary heart disease (CHD). More recently, interest has grown in the potential value of including nuts in the diets of individuals with diabetes. Data from the Nurses Health Study indicates that frequent nut consumption is associated with a reduced risk of developing diabetes and cardiovascular disease. Randomized controlled trials of patients with type 2 diabetes have confirmed the beneficial effects of nuts on blood lipids also seen in nondiabetic subjects, but the trials have not reported improvement in A1c or other glycated proteins. Acute feeding studies, however, have demonstrated the ability of nuts, when eaten with carbohydrate (bread), to depress postprandial glycemia. Furthermore, there was evidence of reduced postprandial oxidative stress associated with nut consumption. In terms of dietary composition, nuts have a good nutritional profile, are high in monounsaturated fatty acids (MUFA) and PUFA, and are good sources of vegetable protein. Incorporation of nuts in the diet may therefore improve the overall nutritional quality of the diet. We conclude that there is justification to consider the inclusion of nuts in the diets of individuals with diabetes in view of their potential to reduce CHD risk, even though their ability to influence overall glycemic control remains to be established.

Priority areas for research on the intake, composition, and health effects of tree nuts and peanuts

This article summarizes the main conclusions drawn from a conference on the health effects of nut consumption and identifies priority areas for future research. Individuals with higher intakes of nuts generally have higher intakes of many beneficial dietary constituents. More information is needed on nut composition, the bioavailability of nutrients, and other bioactive constituents. Better methods are needed to assess usual nut intake, including biomarkers, and the types, physical form, and amounts of nuts that are consumed. The feasibility of including nuts and seeds as a separate food group in the Dietary Guidelines should be tested, as should ways to increase nut intake. A moderate intake of nuts can be included in a weight loss regimen and further information is needed on whether nuts improve satiety as well as adherence to and efficacy of diets designed for weight reduction. There is substantial evidence that nut consumption reduces risk of cardiovascular disease. Future research should investigate their benefits for prevention of congestive heart failure, including clinical studies in patients with this condition, to evaluate the effects of nuts on markers of heart disease risk. Higher nut consumption is associated with lower risk of diabetes and associated cardiovascular disease. More remains to be learned about the effects of nuts on postprandial glycemic and insulin response, glycemic control, and improvement of disease risk factors in subjects with prediabetes and diabetes. Information is needed on nut-induced allergic reactions, including their prevalence and consequences, causes of sensitization, biomarkers of severe reactions, and cross-reactivity to different types of nuts.

Impact of peanuts and tree nuts on body weight and healthy weight loss in adults

Nuts (ground and tree) are rich sources of multiple nutrients and their consumption is associated with health benefits, including reduced cardiovascular disease risk. This has prompted recommendations to increase their consumption. However, they are also high in fat (albeit largely unsaturated) and are energy dense. The associations between these properties, positive energy balance, and body weight raise questions about such recommendations. This issue is addressed through a review of the literature pertaining to the association between nut consumption and energy balance. Epidemiological studies document an inverse association between the frequency of nut consumption and BMI. Clinical trials reveal little or no weight change with inclusion of various types of nuts in the diet over 1-6 mo. Mechanistic studies indicate this is largely attributable to the high satiety property of nuts, leading to compensatory responses that account for 65-75% of the energy they provide. Limited data suggest chronic consumption is associated with elevated resting energy expenditure resulting in dissipation of another portion of the energy they provide. Additionally, due to poor bioaccessibility, there is limited efficiency of energy absorption from nuts. Collectively, these mechanisms offset much of the energy provided by nuts. The few trials contrasting weight loss through regimens that include or exclude nuts indicate improved compliance and greater weight loss when nuts are permitted. This consistent literature suggests nuts may be included in the diet, in moderation, to enhance palatability and nutrient quality without posing a threat for weight gain.

The role of tree nuts and peanuts in the prevention of coronary heart disease: multiple potential mechanisms

Epidemiologic and clinical trial evidence has demonstrated consistent benefits of nut and peanut consumption on coronary heart disease (CHD) risk and associated risk factors. The epidemiologic studies have reported various endpoints, including fatal CHD, total CHD death, total CHD, and nonfatal myocardial infarct. A pooled analysis of 4 U.S. epidemiologic studies showed that subjects in the highest intake group for nut consumption had an approximately 35% reduced risk of CHD incidence. The reduction in total CHD death was due primarily to a decrease in sudden cardiac death. Clinical studies have evaluated the effects of many different nuts and peanuts on lipids, lipoproteins, and various CHD risk factors, including oxidation, inflammation, and vascular reactivity. Evidence from these studies consistently shows a beneficial effect on these CHD risk factors. The LDL cholesterol-lowering response of nut and peanut studies is greater than expected on the basis of blood cholesterol-lowering equations that are derived from changes in the fatty acid profile of the diet. Thus, in addition to a favorable fatty acid profile, nuts and peanuts contain other bioactive compounds that explain their multiple cardiovascular benefits. Other macronutrients include plant protein and fiber; micronutrients including potassium, calcium, magnesium, and tocopherols; and phytochemicals such as phytosterols, phenolic compounds, resveratrol, and arginine. Nuts and peanuts are food sources that are a composite of numerous cardioprotective nutrients and if routinely incorporated in a healthy diet, population risk of CHD would therefore be expected to decrease markedly.