Torabian, S., E. Haddad, S. Rajaram, J. Banta, J. Sabate’, 2009. Acute effect of nut consumption on plasma total polyphenols, antioxidant capacity and lipid peroxidation. J Hum Nutr Diet. 22:64-71.
Background: Nuts have been shown to have beneficial effects on human health due to the healthy fat content; however, the effect of antioxidants (i.e. polyphenols) in nuts have not been fully investigated. The present study aimed to assess the immediate effect of a polyphenol-rich meal (75% of energy from nuts: walnuts or almonds) and a polyphenol-free meal on plasma polyphenol content, antioxidant capacity and lipid peroxidation in healthy volunteers. Methods: Thirteen subjects participated in a randomized, crossover, intervention study. After an overnight fast, walnuts, almonds or a control meal in the form of smoothies were consumed by study subjects. Each subject participated on three occasions, 1 week apart, consuming one of the smoothies each time. Blood samples were obtained at fasting and then at intervals up to 3.5 h after consumption of the smoothies. Results: There was a significant increase in plasma polyphenol concentration following both nut meals, with peak concentrations being achieved at 90 min, and with a walnut meal having a more sustained higher concentration than an almond meal. The plasma total antioxidant capacity reached its highest point at 150 min postconsumption of the nut meals, and was higher after the almond compared to walnut meal. A gradual significant (P < 0.05) reduction in the susceptibility of plasma to lipid peroxidation was observed 90 min after ingestion of the nut meals. No changes were observed following consumption of control meal. Conclusions: Consumption of both nuts increased plasma polyphenol concentrations, increased the total antioxidant capacity and reduced plasma lipid peroxidation.
Hardman, W.E., G. Ion, 2008. Suppression of implanted MDA-MB 231 human breast cancer growth in nude mice by dietary walnut. Nutrition and Cancer. 60:5,666-674.
Walnuts contain components that may slow cancer growth including omega 3 fatty acids, phytosterols, polyphenols, carotenoids, and melatonin. A pilot study was performed to determine whether consumption of walnuts could affect growth of MDA-MB 231 human breast cancers implanted into nude mice. Tumor cells were injected into nude mice that were consuming an AIN-76A diet slightly modified to contain 10% corn oil. After the tumors reached 3 to 5 mm diameter, the diet of one group of mice was changed to include ground walnuts, equivalent to 56 g (2 oz) per day in humans. The tumor growth rate from Day 10, when tumor sizes began to diverge, until the end of the study of the group that consumed walnuts (2.9 ± 1.1 mm3/day; mean ± standard error of the mean) was significantly less (P < 0.05, t-test of the growth rates) than that of the group that did not consume walnuts (14.6 ± 1.3 mm3/day). The eicosapentaenoic and docosahexaenoic acid fractions of the livers of the group that consumed walnuts were significantly higher than that of the group that did not consume walnuts. Tumor cell proliferation was decreased, but apoptosis was not altered due to walnut consumption. Further work is merited to investigate applications to cancer in humans.
Seeram, N.P., Y. Zhang, S.M. Henning, R. Lee, Y. Niu, G. Lin, D. Heber, 2006. Pistachio skin phenolics are destroyed by bleaching resulting in reduced antioxidative capacities. J. Agric. Food Chem. 54:7036-7040.
Pistachio shells split naturally prior to maturity leading to their unique crack-shell form. Within 24 h of harvest, hull-trapped moisture may cause shell staining. The illegal process of bleaching has been used to restore a desirable white color to pistachio shells. It is not known whether bleaching adversely affects phytochemical levels in pistachios. Therefore, we identified for the first time multiple pistachio skin phenolics as quercetin (14.9 µg/g), luteolin (10.0 µg/g), eriodictyol (10.2 µg/g), rutin (1.6 µg/g), naringenin (1.2 µg/g), apigenin (0.2 µg/g), and the anthocyanins, cyanidin-3-galactoside (696 µg/g) and cyanidin-3-glucoside (209 µg/g). We investigated the effects of bleaching (0.1-50% hydrogen peroxide) on phenolic levels and antioxidative capacities in raw and roasted nuts. Because of their flavylium cation structures, anthocyanins were the most sensitive to bleaching. Bleaching decreased total anthocyanin levels [íg/g of skins (% hydrogen peroxide)]: 905 and 549 (0%); 653 and 145 (0.1%); 111 and 18.4 (5%); 6.1 and 3.2 (25%); 0 and 0 (50%) for raw and roasted nuts, respectively. Bleaching also reduced antioxidative capacity [µM/g of Trolox (% hydrogen peroxide)]: 945 and 725 (0%); 940 and 472 (0.1%); 930 and 455 (5%); 433 and 370 (25%); 189 and 173 (50%), for raw and roasted nuts, respectively. Raw nuts preserved phenolic levels and antioxidant capacity better than roasted nuts, suggesting contributing effects of other substances and/or matrix effects that are destroyed by the roasting process. The destruction of bioactive phenolics in pistachio skins may negatively impact the potential health benefits arising from pistachio consumption.
Nichenametla, N.E., T.G. Taruscio, D.L. Barney, J.H. Exon, 2006. A Review of the effects and mechanisms of polyphenolics in cancer. Critical Reviews in Food Science and Nutrition, 46:161-183.
This paper is a comprehensive review of the effects of bioactive polyphenolic compounds commonly found in many fruits and vegetables on cancer. These include the phenolic acids, anthocyanins, catechins, stilbenes and several other flavonoids. We have attempted to compile information from most of the major studies in this area into one source. The review encompasses the occurrence and bioavailability of the polyphenolics, the in vitro and in vivo evidence for their effects on cancer, both positive and negative, and the various mechanisms by which the chemicals may exert their effects. Although most of the work done to date indicates a chemopreventative activity of these compounds, there are some studies that show cancer-inducing or no effects. There are several common mechanisms by which these chemicals exert their effects that could be conducive to additive, synergistic, or antagonistic interactions. These include effects on cellular differentiation, proliferation, and apoptosis, effects on proteins and enzymes that are involved in these processes at a molecular level, and other various effects through altered immune function and chemical metabolism.
Haddad, E., P. Jambazian, M. Karunia, J. Tanzman, J. Sabaté, 2006. A pecan-enriched diet increases γ-tocopherol/cholesterol and decreases thiobarbituric acid reactive substances in plasma of adults. Nutrition Research. 26:397-402.
Consumption of nuts is associated with a reduced risk of coronary heart disease, and dietary intervention studies incorporating pecans show improved lipid profiles. The unsaturated fats in pecans are protected against oxidation by the high concentrations of γ-tocopherol and polymeric flavanols. The aim of this study was to determine whether plasma concentrations of tocopherols and measures of antioxidant capacity and of oxidative stress are affected by incorporation of pecans in the diet. In a randomized, controlled, crossover feeding study, 24 subjects were assigned to 2 diets, each for 4 weeks: a control diet and a pecan-enriched (20% of energy) diet. Cholesterol-adjusted plasma γ-tocopherol increased by 10.1% ( P < .001), a-tocopherol decreased by 4.6% ( P < .001), and malondialdehyde concentrations measured as thiobarbituric acid reactive substances decreased by 7.4% (P < .05) on the pecan diet. No changes were observed for ferric-reducing ability of plasma or Trolox equivalent antioxidant capacity values. These data provide some evidence for potential protective effects of pecan consumption in healthy individual
Wijeratne, S.S.K.; R.. Amarowicz, F. Shahidi, 2006. Antioxidant activity of almonds and their by-products in food model systems. JAOCS. 83(3):223-230.
Antioxidant activities of almond whole seed, brown skin, and green shell cover extracts, at 100 and 200 ppm quercetin equivalents, were evaluated using a cooked comminuted port mode, a β-carotene-linoteate model, and a bulk stripped corn oil system. Retention of β-carotene in a β-carotene-linoleate model system by almond whole seed, brown skin, and green shell cover extracts was 84-96, 74-83, and 71-93% respectively. In a bulk stripped corn oil system, green shell cover extract performed better than brown skin and whole seed extracts in inhibiting the formation of both primary and secondary oxidation products, while in a cooked comminuted port model system, green shell cover and brown skin extracts inhibited the formation of TBARS, total volatiles and hexanal more effectively than did the whole seed extract. HPLC analysis revealed the presence of caffeic, ferulic, p-coumaric and sinapic acids as the major phenolic acids in all three almond extracts examined.
Wijeratne, S. S. K., M. M. Abou-Zaid, and F. Shahidi. 2006. Antioxidant polyphenols in almond and its coproducts. J. Agric. Food Chem. 54:312-318.
Antioxidant efficacy of defatted almond whole seed, brown skin, and green shell cover extracts was evaluated by monitoring inhibition of human low-density lipoprotein (LDL) oxidation, inhibition of DNA scission, and metal ion chelation activities. The total phenolic contents of ethanolic extracts of brown skin and green hell cover of almond were 10 and 9 times higher than that of the whole seed, respectively. Brown skin extract at 50 ppm effectively inhibited copper-induced oxidation of human LDL cholesterol compared to whole seed and green shell cover extracts, which reached the same level of efficacy at 200 ppm. Green shell over extract at 50 ppm level completely arrested peroxyl radical-induced DNA scission, whereas 100 ppm of brown skin and whole seed extracts was required for similar efficiencies. All three almond extracts exhibited excellent metal ion chelation efficacies. High-performance liquid chromatographic (HPLC) analysis revealed the presence of quercetin, isorhamnetin, quercitrin, kaempferol 3-O-rutinoside, isorhamnetin 3-O-glucoside, and morin as the major flavonoids in all extracts.
Jia, X., N. Li, W. Zhang, X. Zhang, K. Lapsley, G. Huang, J. Blumberg, G. Ma, J. Chen, 2006. A pilot study on the effects of almond consumption on DNA damage and oxidative stress in smokers. Nutrition and Cancer. 54(2), 179-183.
The effects of almond consumption on DNA damage and oxidative stress among cigarette smokers were studied. Thirty healthy adult male regular smokers were randomly divided into three groups, 10 subjects per group. Group A (control group) did not receive any almonds. Subjects in Groups B and C received 3 oz and 6 oz (84 g and 168 g) of almonds each day respectively for 4 wk. Two known biomarkers for DNA damage, urinary 8-hydroxy-2′-deoxyguanosine (8-OH-dG) and single strand DNA breaks of peripheral blood lymphocytes, were measured by enzyme-linked immunosorbent assay and comet assay, respectively. In addition, plasma malondialdehyde (MDA) level, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities were measured as biomarkers for oxidative stress. The results showed lower levels of urinary 8-OH-dG and single strand DNA breaks in the two almond-treated groups as compared with the control group. Furthermore, MDA levels in the almond-treated groups were lower than the controls. However, no significant effects of almonds on SOD and GSH-PX activities were found. In conclusion, results from this pilot study indicate that almond consumption has preventive effects on oxidative stress and DNA damage caused by smoking. A larger, randomized, placebo-controlled clinical trial on almonds will be initiated in the near future.
Gonzalez, C.A., J. Salas-Salvado’, 2006. The potential of nuts in the prevention of cancer. British Journal of Nutrition. 96, Suppl. 2, S87-S94.
Cancer is a disease that is characterized by the loss of genetic control over cell growth and proliferation, mainly as a result of the exposure to environmental factors. Cessation of smoking and a high consumption of fruits and vegetables are the most important means of reducing the risk of cancer in our society. Like fruits and vegetables, nuts are a source of vegetable protein, monounsaturated fatty acids, vitamin E, phenolic compounds, selenium, vegetable fiber, folic acid and phytoestrogens. There are numerous mechanisms of action by which these components can intervene in the prevention of cancer, although they have not been fully elucidated. There are very few epidemiological studies analyzing the relationship between nuts consumption and risk of cancer. One of the greatest difficulties in interpreting the results is that the consumption of nuts, seeds and legumes are often presented together. The most commonly studied location is the colon/rectum, an organ in which the effect of nuts is biologically plausible. Although the results are not conclusive, a protective effect on colon and rectum cancer is possible. Likewise, some studies show a possible protective effect on prostate cancer, but there is insufficient data on other tumor locations. New epidemiological studies are required to clarify the possible effects of nuts on cancer, particularly prospective studies that make reliable and complete estimations of their consumption and which make it possible to analyze their effects independently of the consumption of legumes and seeds.
Blomhoff, R., M.H. Carlsen, L.F. Andersen, D.R. Jacobs Jr, 2006. Health benefits of nuts: potential role of antioxidants. British Journal of Nutrition. 96, Suppl. 2, S52-S60.
A diet rich in fruits, vegetables and minimally refined cereals is associated with lower risk for chronic degenerative diseases. Since oxidative stress is common in chronic degenerative disease, it has been assumed that dietary antioxidants may explain this protective effect. Every dietary plant contains numerous types of antioxidants with different properties. Many of these antioxidants cooperate in oxidative stress reduction in plants, and we hypothesize that many different antioxidants may also be needed for the proper protection of animal cells. To test this hypothesis, it is useful to identify dietary plants with high total antioxidant content. Several nuts are among the dietary plants with the highest content of total antioxidants. Of the tree nuts, walnuts, pecans and chestnuts have the highest contents of antioxidants. Walnuts contain more than 20 mmol antioxidants per 100 g, mostly in the walnut pellicles. Peanuts (a legume) also contribute significantly to dietary intake of antioxidants. These data are in accordance with our present extended analysis of an earlier report on nut intake and death attributed to various diseases in the Iowa Women’s Health Study. We observed that the hazard ratio for total death rates showed a U-shaped association with nut/peanut butter consumption. Hazard ratio was 0.89 (CI= 0.81-0.97) and 0.81 (CI= 0.75-0.88) for nut/peanut butter intake once per week and 1-4 times per week, respectively. Death attributed to cardiovascular and coronary heart diseases showed strong and consistent reductions with increasing nut/peanut butter consumption. Further studies are needed to clarify whether antioxidants contribute to this apparent beneficial health effect of nut
