Consumption of vegetables and fruits and risk of breast cancer.
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Biomedical subjects
Publications and source records attributed to Bernhard Watzl.
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The HDL-bound enzyme paraoxonase (PON) protects LDL from oxidation and may therefore attenuate the development of atherosclerosis. We examined the effect of tomato and carrot juice consumption on PON1 activity and lipid peroxidation in healthy young volunteers with different PON1-192 genotypes (Q/R substitution at position 192). In this randomized cross-over study twenty-two healthy, non-smoking men on a low-carotenoid diet received 330 ml/d tomato juice (37.0 mg lycopene, 1.6 mg beta-carotene) or carrot juice (27.1 mg beta-carotene, 13.1 mg alpha-carotene) for 2 weeks. Intervention periods were preceded by 2-week low-carotenoid intake. We determined the PON1-192 genotype by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) and measured ex vivo LDL oxidation (lag time), plasma malondialdehyde and PON1 activity at the beginning and end of each intervention period. At baseline, lag time was higher (P<0.05) in QQ (111 (sd 9) min) than in QR/RR subjects (101 (sd 8) min). Neither tomato nor carrot juice consumption had significant effects on PON1 activity. However, tomato juice consumption reduced (P<0.05) plasma malondialdehyde in QR/RR (Delta: -0.073 (sd 0.11) micromol/l) as compared to QQ subjects (Delta:+0.047 (sd 0.13) micromol/l). Carrot juice had no significant effect on malondialdehyde irrespective of the PON1-192 genotype. Male volunteers with the QR/RR genotype showed an increased lipid peroxidation at baseline. Although tomato and carrot juice fail to affect PON1 activity, tomato juice intake reduced lipid peroxidation in healthy volunteers carrying the R-allele of the PON1-192 genotype and could thus contribute to CVD risk reduction in these individuals.
Diet is known to modulate immune functions in multiple ways and to affect host resistance to infections. Besides the essential nutrients, non-essential food constituents such as non-digestible carbohydrates may also have an impact on the immune system, especially in the area of the gut-associated lymphoid tissue (GALT). Recent data now provide first evidence that prebiotics such as inulin/oligofructose (IN/OF) modulate functions of the immune system. In animal studies IN/OF primarily activated immune cells in Peyer's patches including IL-10 production and natural killer (NK) cell cytotoxicity. Other immune functions modulated by IN/OF included the concentration of secretory IgA in ileum and caecum, splenic NK cell cytotoxicity as well as splenocyte cytokine production. In different tumour models, a lower incidence of tumours was observed, which in the case of colonic tumours was associated with enhanced NK cell cytotoxicity in the GALT. Few human studies so far have investigated the effects of IN/OF alone or in combination with other dietary supplements on immunocompetence. Supplementation of IN/OF resulted in minor changes of systemic immune functions such as decrease in phagocytic activity. No data are available on the effects of IN/OF on the GALT in man. The mechanisms of the reported effects of IN/OF on the immune system are currently investigated and include: (i) direct effects of lactic acid-producing bacteria or bacterial constituents on immune cells; (ii) the production of SCFA and binding to SCFA receptors on leucocytes. In conclusion, the current data suggest that IN/OF primarily modulate immune parameters in the GALT, but splenocytes are also activated by IN/OF. Human studies are needed to find out whether IN/OF have the potential to modulate systemic immunity in well-nourished individuals and to lower the risk of diseases such as colon cancer.
Normal functioning of the immune system is crucial to the health of man, and diet is one of the major exogenous factors modulating individual immunocompetence. Recently, nutrition research has focused on the role of foods or specific food components in enhancing immune system responsiveness to challenges and thereby improving health and reducing disease risks. Assessing diet-induced changes of immune function, however, requires a thorough methodological approach targeting a large spectrum of immune system parameters. Currently, no single marker is available to predict the outcome of a dietary intervention on the resistance to infection or to other immune system-related diseases. The present review summarises the immune function assays commonly used as markers in human intervention studies and evaluates their biological relevance (e.g. known correlation with clinically relevant endpoints), sensitivity (e.g. within- and between-subject variation), and practical feasibility. Based on these criteria markers were classified into three categories with high, medium or low suitability. Vaccine-specific serum antibody production, delayed-type hypersensitivity response, vaccine-specific or total secretory IgA in saliva and the response to attenuated pathogens, were classified as markers with high suitability. Markers with medium suitability include natural killer cell cytotoxicity, oxidative burst of phagocytes, lymphocyte proliferation and the cytokine pattern produced by activated immune cells. Since no single marker allows conclusions to be drawn about the modulation of the whole immune system, except for the clinical outcome of infection itself, combining markers with high and medium suitability is currently the best approach to measure immunomodulation in human nutrition intervention studies. It would be valuable to include several immune markers in addition to clinical outcome in future clinical trials in this area, as there is too little evidence that correlates markers with global health improvement.
BACKGROUND: Whether different intakes of vegetables and fruit modulate immunologic markers is currently not known. OBJECTIVE: We investigated the effects of low, medium, and high intakes of vegetables and fruit on markers of immune functions, including nonspecific markers of inflammation. DESIGN: In a randomized controlled trial, nonsmoking men consumed a diet that included < or = 2 servings/d of vegetables and fruit for 4 wk. The subjects were then randomly assigned to 1 of 3 groups to consume 2 servings/d, 5 servings/d, or 8 servings/d of carotenoid-rich vegetables and fruit for another 4-wk period. Plasma concentrations of vitamins C and E and carotenoids were measured. The assessment of immunologic and inflammatory markers included the number and activity of natural killer cells, secretion of cytokines, lymphocyte proliferation, and plasma C-reactive protein concentrations. RESULTS: The high intake (8 servings/d) of vegetables and fruit significantly increased total carotenoid concentrations in plasma compared with the low intake (2 servings/d; week 4 compared with week 8), whereas concentrations of vitamins C and E did not differ between week 4 and week 8. Immunologic markers were not significantly modulated. In contrast, C-reactive protein was significantly reduced at week 8 in the subjects who consumed 8 servings/d of vegetables and fruit compared with those who consumed 2 servings/d. CONCLUSIONS: In healthy, well-nourished, nonsmoking men, 4 wk of low or high intakes of carotenoid-rich vegetables and fruit did not affect markers of immune function. However, a high intake of vegetables and fruit may reduce inflammatory processes, as indicated by the reduction of plasma C-reactive protein.
This study investigated whether a 21.1 km (half-marathon) or a 42.195 km (marathon) run modulates DNA damage, antioxidant capacity in lymphocytes and plasma, and the immune system in healthy hobby runners. Ten and 12 volunteers who completed the Baden-Marathon race in Karlsruhe with a running distance of 21.1 km and 41.195 km, respectively, were assessed 10 days before and immediately after the finish. There was no increase in the levels of endogenous DNA strand breaks immediately after half-marathon or marathon races. A statistically significant increase in the levels of oxidative DNA damage in lymphocytes was found using endonuclease III but not formamidopyrimidine glycolase (Fpg). The resistance of DNA to oxidative damage induced by hydrogen peroxide in isolated lymphocytes was significantly decreased after both races. The levels of plasma antioxidants such as alpha-tocopherol, beta-carotene and lycopene were close to, or higher than, those considered optimal for reducing the risk of cardiovascular diseases and there were no significant changes after the races in antioxidant capacity of LDL (lag-time test) or plasma in ORAC, TEAC or paraoxonase assays. The number and percentage of granulocytes and monocytes able to generate oxidative burst were significantly increased after both races, but the lytic activity of NK cells was significantly increased at the end of the half-marathon; no effect was observed in the marathon runners. Thus, oxidative DNA damage in lymphocytes, decreased the antioxidant capacity to protect lymphocytes against DNA strand breaks and increased the formation of reactive species by phagocytes in well-nourished hobby runners indicating moderate oxidative damage during such high-intensity exercise.
Increased consumption of tomato products is associated with a decreased risk of cancer. The present study was performed to investigate whether consumption of a tomato oleoresin extract for 2 weeks can affect endogenous levels of DNA single strand breaks in peripheral blood lymphocytes in healthy non-smokers and smokers. We also assessed, the effect of the tomato oleoresin extract on various immunological functions of peripheral blood mononuclear cells. A double-blinded, randomized, placebo-controlled study design was used. Over a period of 2 weeks 15 non-smokers and 12 smokers were given three tomato oleoresin extract capsules daily (each containing 4.88 mg lycopene, 0.48 mg phytoene, 0.44 mg phytofluene and 1.181 mg alpha-tocopherol). The control group received placebos. The baseline level of endogenous DNA damage for non-smokers was slightly (13%) and non-significantly (P = 0.44) lower than that of smokers. Placebo supplementation of non-smokers and smokers for 2 weeks did not significantly affect lycopene plasma levels or DNA damage in either group. Intervention with tomato oleoresin extract resulted in significant increases in total plasma lycopene and resulted in decreased levels of DNA strand breaks of approximately 32 (non-smokers) and 39% (smokers). However, this effect was not statistically significant in either group (P = 0.09 for non-smokers and P = 0.12 for smokers). Analysis of the distribution pattern of DNA strand breaks showed a statistically significant (P < 0.05) increase in the number of comets in class 0 (undamaged) and a decrease in classes 1 and 2 (damaged) after the tomato oleoresin extract intervention in non-smokers. The changes in the smoker group were not statistically significant. Treatment with the tomato extract had no effect on lymphocyte proliferation, NK cell activity, interleukin (IL)-2 production and tumor necrosis factor (TNF)alpha production, but it significantly reduced IL-4 production in smokers (P = 0.009).
BACKGROUND: The gut and immune system form a complex integrated structure that has evolved to provide effective digestion and defence against ingested toxins and pathogenic bacteria. However, great variation exists in what is considered normal healthy gut and immune function. Thus, whilst it is possible to measure many aspects of digestion and immunity, it is more difficult to interpret the benefits to individuals of variation within what is considered to be a normal range. Nevertheless, it is important to set standards for optimal function for use both by the consumer, industry and those concerned with the public health. The digestive tract is most frequently the object of functional and health claims and a large market already exists for gut-functional foods worldwide. AIM: To define normal function of the gut and immune system and describe available methods of measuring it. RESULTS: We have defined normal bowel habit and transit time, identified their role as risk factors for disease and how they may be measured. Similarly, we have tried to define what is a healthy gut flora in terms of the dominant genera and their metabolism and listed the many, varied and novel methods for determining these parameters. It has proved less easy to provide boundaries for what constitutes optimal or improved gastric emptying, gut motility, nutrient and water absorption and the function of organs such as the liver, gallbladder and pancreas. The many tests of these functions are described. We have discussed gastrointestinal well being. Sensations arising from the gut can be both pleasant and unpleasant. However, the characteristics of well being are ill defined and merge imperceptibly from acceptable to unacceptable, a state that is subjective. Nevertheless, we feel this is an important area for future work and method development. The immune system is even more difficult to make quantitative judgements about. When it is defective, then clinical problems ensure, but this is an uncommon state. The innate and adaptive immune systems work synergistically together and comprise many cellular and humoral factors. The adaptive system is extremely sophisticated and between the two arms of immunity there is great redundancy, which provides robust defences. New aspects of immune function are discovered regularly. It is not clear whether immune function can be "improved". Measuring aspects of immune function is possible but there is no one test that will define either the status or functional capacity of the immune system. Human studies are often limited by the ability to sample only blood or secretions such as saliva but it should be remembered that only 2% of lymphocytes circulate at any given time, which limits interpretation of data. We recommend assessing the functional capacity of the immune system by: measuring specific cell functions ex vivo. measuring in vivo responses to challenge, e. g. change in antibody in blood or response to antigens. determining the incidence and severity of infection in target populations during naturally occurring episodes or in response to attenuated pathogens.
Probiotics (PRO) are known to modulate immunity in animals and human subjects and to inhibit colon carcinogenesis in experimental models, but the effects of synbiotics (SYN) are not well understood. Therefore, the effects of PRO (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12), PRE (inulin-based enriched with oligofructose, 100 g/kg) and SYN (combination of PRO and PRE) on the immune system of rats were investigated in the azoxymethane (AOM)-induced colon cancer model. After 33 weeks, rats with and without AOM treatment were killed and immune cells were isolated from spleen, mesenterial lymph nodes (MLN) and Peyer's patches (PP). AOM treatment significantly reduced natural killer (NK) cell-like cytotoxicity in control rats and in PRO- and PRE-supplemented rats. SYN supplementation prevented the AOM-induced suppression of NK cell-like cytotoxicity in PP compared with control rats (P<0.01). SYN and PRE supplementation stimulated IL-10 production in PP in these rats (P<0.01) and in MLN of rats not treated with AOM (P<0.05). Interferon-gamma production in PP was decreased by PRO supplementation (PRO and SYN groups combined; P<0.05). Proliferative responsiveness of lymphocytes (PP) from AOM-treated rats was suppressed in SYN-supplemented rats (P<0.01). Overall, SYN supplementation in carcinogen-treated rats primarily modulated immune functions in the PP, coinciding with a reduced number of colon tumours. PRE and PRO provided in combination as SYN may contribute to the suppression of colon carcinogenesis by modulating the gut-associated lymphoid tissue.
Probiotics (PRO) modulate systemic immunity in animals and humans. In contrast, the effects of prebiotics (PRE) on systemic and intestinal immunity have not been investigated. Whether the combined application of PRO and PRE [synbiotics (SYN)] has synergistic or additive effects is presently unknown. Therefore, PRO (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12), PRE (inulin enriched with oligofructose), and SYN (combination of PRO and PRE) were fed to F344 rats for 4 wk as supplements to a high fat diet. Functions of immune cells isolated from peripheral blood mononuclear cells (PBMC), spleen, mesenterial lymph nodes and Peyer's patches (PP) were investigated. The SYN supplement increased secretory immunoglobulin A (sIgA) production in the ileum compared with controls fed the high fat diet alone (P<0.05), and decreased the oxidative burst activity of blood neutrophils (P<0.05) compared with rats fed PRO. The PRE supplement enhanced the production of interleukin-10 (P<0.05) in PP as well as the production of sIgA in the cecum (P<0.05), compared with controls. The PRO supplement modestly affected immune functions, whereas systemic immunomodulatory effects were observed in rats fed SYN. The PRE supplement primarily acted at the level of the gut-associated lymphoid tissue. The combined application of PRO and PRE has different effects from those of the individual supplements, but does not simply result in additive or synergistic effects.
Polyphenolic compounds exert a variety of physiological effects in vitro including antioxidative, immunomodulatory and antigenotoxic effects. In a randomized crossover study in healthy men on a low-polyphenol diet, we determined the effects of 2 polyphenol-rich juices (330 ml/d) supplemented for 2 weeks on bioavailability of polyphenols, markers of antioxidative and immune status, and reduction of DNA damage. Juices provided 236 mg (A) and 226 mg (B) polyphenols with cyanidin glycosides (A) and epigallocatechin gallate (B) as major polyphenolic ingredients. There was no accumulation of plasma polyphenols after two weeks of juice supplementation. In contrast, plasma malondialdehyde decreased with time during juice interventions. Moreover, juice consumption also increased lymphocyte proliferative responsiveness, with no difference between the two juices. Interleukin-2 secretion by activated lymphocytes and the lytic activity of natural killer cells were significantly increased by both juices. Juice intervention had no effect on single DNA strand breaks, but significantly reduced oxidative DNA damage in lymphocytes. A time-delay was observed between the intake of fruit juice and the reduction of oxidative DNA damage and the increase in interleukin-2 secretion. We conclude that consumption of either juice enhanced antioxidant status, reduced oxidative DNA damage and stimulated immune cell functions. However, fruit juice consumption for 2 weeks did not result in elevated plasma polyphenols in subjects after overnight fasting. Further studies should focus on the time-delay between juice intake and changes in measured physiological functions, as well as on active polyphenolic metabolites mediating the observed effects.
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BACKGROUND: Beta-carotene has been shown to enhance immune functions in humans. Whether vegetables rich in carotenoids, such as beta-carotene or lycopene, modulate immune functions in healthy humans is presently not known. The objective of this study was to investigate the effects of a low-carotenoid diet supplemented with either tomato (providing high amounts of lycopene) or carrot juice (providing high amounts of alpha- and beta-carotene) on immune functions in healthy men. METHOD: In a blinded, randomized, cross-over study, male subjects on a low-carotenoid diet consumed 330 ml/day of either tomato juice (37.0 mg/day lycopene) or carrot juice (27.1 mg/day beta-carotene and 13.1 mg/day alpha-carotene) for 2 weeks with a 2-week depletion period after juice intervention. Immune status was assessed by measuring lytic activity of natural killer (NK) cells, secretion of cytokines (IL-2, IL-4, TNFalpha), and proliferation by activated peripheral blood mononuclear cells. RESULTS: Juice consumption resulted in relatively fast responses in plasma carotenoid concentrations (p < 0.0002) which were not accompanied by concomitant changes in immune functions. For IL-2, NK cell cytotoxicity, and lymphocyte proliferation, maximum responses were observed during depletion periods. The highest production rate was measured only for TNFalpha at the end of the first intervention period. Juice intervention did not modulate the secretion of IL-4. CONCLUSIONS: Increased plasma carotenoid concentrations after vegetable juice consumption are accompanied by a time-delayed modulation of immune functions in healthy men consuming a low-carotenoid diet.
BACKGROUND: A recent prospective cohort study revealed that moderate wine consumption but not consumption of other alcoholic beverages is associated with a decreased risk of common cold. In contrast, wine constituents such as ethanol and polyphenols are known to suppress immunity. AIM OF THE STUDY: We investigated whether acute intake of a moderate amount of alcohol modulates immune functions in healthy men and whether polyphenols in red wine with antioxidative and immunomodulatory potential induce changes in immune functions that differ from those induced by the consumption of the 12 % ethanol. METHODS: Six healthy males with moderate alcohol consumption patterns randomly consumed a single dose of 500 ml of red wine (12 % ethanol), a 12 % ethanol dilution, dealcoholized red wine, and red grape juice, respectively. The following immune functions were measured before beverage consumption and 1, 3, and 24 h later: phagocytic activity and intensity of neutrophils and monocytes, production of tumor necrosis factor-alpha, interleukin-2, and interleukin-4, lymphocyte proliferation, and lytic activity of natural killer cells. RESULTS: Acute consumption of a moderate amount of red wine and of a 12 % ethanol solution had no effect on immune functions in men. Acute consumption of polyphenol-rich beverages (dealcoholized red wine and red grape juice) also did not affect immunity. CONCLUSIONS: This study clearly shows that moderate consumption of alcohol at doses which inversely correlate with cardiovascular disease risk has no short-term effect on human immune cell functions. Acute intake of polyphenol-rich beverages such as red grape juice and dealcoholized red wine also does not affect immunity.
BACKGROUND: The oxidative modification of LDL is considered to play a central role in the pathogenesis of atherosclerosis and coronary heart disease (CHD). Paraoxonase (PON1) protects LDL from oxidation and may therefore retard the development of atherosclerosis. The PON1-192 polymorphism is associated with diminished PON1 concentrations and an increased risk for CHD in RR-allele subjects. AIM OF THE STUDY: To investigate the effect of tomato juice consumption on PON1 activity and other parameters related to oxidative stress in healthy elderly subjects. Furthermore, the PON1-192 genotype has been determined in the volunteers in order to see whether possible treatment effects are related to the PON1-192 polymorphism. METHODS: Fifty elderly subjects were randomly assigned to control (mineral water) or intervention group (tomato juice). Subjects of the tomato juice group consumed daily 330 mL tomato juice for 8 weeks. Antioxidant status was measured as LDL oxidation, plasma malondialdehyde, ferric reducing ability of plasma (FRAP) and PON1 activity. The PON1-192 polymorphism was determined by restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR). Plasma carotenoids were analyzed by HPLC. RESULTS: Tomato juice consumption reduced LDL-oxidation and improved antioxidant status in R-allele carriers, but not in the QQ genotype group. PON1 activity increased irrespective of the genotype in both, control and intervention group. CONCLUSIONS: The changes in antioxidant status after tomato juice consumption seem to depend on the PON1-192 genotype. Healthy elderly, carrying the R-allele, could specifically reduce their higher cardiovascular risk by changing dietary habits.