Sabine Ellinger

Critical review: vegetables and fruit in the prevention of chronic diseases

BackgroundVegetables and fruit provide a significant part of human nutrition, as they are important sources of nutrients, dietary fibre, and phytochemicals. However, it is uncertain whether the risk of certain chronic diseases can be reduced by increased consumption of vegetables or fruit by the general public, and what strength of evidence has to be allocated to such an association.MethodsTherefore, a comprehensive analysis of the studies available in the literature and the respective study results has been performed and evaluated regarding obesity, type 2 diabetes mellitus, hypertension, coronary heart disease (CHD), stroke, cancer, chronic inflammatory bowel disease (IBD), rheumatoid arthritis (RA), chronic obstructive pulmonary disease (COPD), asthma, osteoporosis, eye diseases, and dementia. For judgement, the strength of evidence for a risk association, the level of evidence, and the number of studies were considered, the quality of the studies and their estimated relevance based on study design and size.ResultsFor hypertension, CHD, and stroke, there is convincing evidence that increasing the consumption of vegetables and fruit reduces the risk of disease. There is probable evidence that the risk of cancer in general is inversely associated with the consumption of vegetables and fruit. In addition, there is possible evidence that an increased consumption of vegetables and fruit may prevent body weight gain. As overweight is the most important risk factor for type 2 diabetes mellitus, an increased consumption of vegetables and fruit therefore might indirectly reduces the incidence of type 2 diabetes mellitus. Independent of overweight, there is probable evidence that there is no influence of increased consumption on the risk of type 2 diabetes mellitus. There is possible evidence that increasing the consumption of vegetables and fruit lowers the risk of certain eye diseases, dementia and the risk of osteoporosis. Likewise, current data on asthma, COPD, and RA indicate that an increase in vegetable and fruit consumption may contribute to the prevention of these diseases. For IBD, glaucoma, and diabetic retinopathy, there was insufficient evidence regarding an association with the consumption of vegetables and fruit.ConclusionsThis critical review on the associations between the intake of vegetables and fruit and the risk of several chronic diseases shows that a high daily intake of these foods promotes health. Therefore, from a scientific point of view, national campaigns to increase vegetable and fruit consumption are justified. The promotion of vegetable and fruit consumption by nutrition and health policies is a preferable strategy to decrease the burden of several chronic diseases in Western societies.

Epicatechin ingested via cocoa products reduces blood pressure in humans: a nonlinear regression model with a Bayesian approach

BACKGROUND Four meta-analyses of randomized controlled trials (RCTs) based on the classical random-effects model showed that cocoa consumption can reduce systolic blood pressure (SBP) and diastolic blood pressure (DBP). Because epicatechin is suggested to be responsible for the treatment effect, changes in blood pressure should depend on the dose of ingested epicatechin, which may explain the between-study differences. OBJECTIVE The objective was to quantify the effect of epicatechin ingested via cocoa products on changes in SBP and DBP. DESIGN A nonlinear meta-regression model was chosen to investigate the impact of the epicatechin dose on changes in SBP and DBP. A Bayesian approach using Markov chain Monte Carlo methods was applied for an appropriate treatment of the nonlinearity. RESULTS Data from 16 RCTs on SBP and 15 RCTs on DBP were included. The dose of epicatechin ingested via cocoa products influenced the changes in SBP and DBP. The asymptotic limit for the reduction was estimated at -4.6 mm Hg (95% CI: -5.4, -3.9 mm Hg) for SBP and at -2.1 mm Hg (95% CI: -2.7, -1.6 mm Hg) for DBP. An intake of 25 mg epicatechin/d led to a mean reduction of -4.1 mm Hg (95% CI: -4.6, -3.6 mm Hg) in SBP and of -2.0 mm Hg (95% CI: -2.4, -1.5 mm Hg) in DBP. CONCLUSIONS Blood pressure reduction by consumption of cocoa products depends on the dose of ingested epicatechin, which explains most of the between-study differences in classical meta-analyses. Similar effects may be achieved by consumption of other foods that are also rich in epicatechin.

Tomatoes, tomato products and lycopene in the prevention and treatment of prostate cancer: do we have the evidence from intervention studies?

Purpose of reviewLycopene-rich foods such as fresh tomatoes and tomato products are discussed as potential effectors in the prevention and therapy of prostate cancer. This review provides an overview on the efficacy of supplementation with tomatoes, tomato products and lycopene on appropriate surrogate endpoint biomarkers such as DNA damage and metabolites of the insulin-like growth factor pathway in healthy individuals and prostate cancer patients. Recent findingsIntervention studies show that the daily consumption of one serving of tomatoes or tomato products, but not supplementation with lycopene alone, increases the resistance of mononuclear leukocytes against DNA strand breaks induced by reactive oxygen species in healthy volunteers. Data from clinical trials with prostate cancer patients are scarce and contradictory. There is a paucity of reliable data on DNA damage in prostate tissue. SummaryIncreasing evidence suggests that a single serving of tomatoes or tomato products ingested daily may contribute to protect from DNA damage. As DNA damage seems to be involved in the pathogenesis of prostate cancer, the regular ingestion of tomatoes or tomato products might prevent the disease. Further well-designed studies are necessary to establish the role of tomatoes and tomato products in the prevention and therapy of prostate cancer.

Consumption of green tea or green tea products: is there an evidence for antioxidant effects from controlled interventional studies?

PURPOSE Epidemiological data suggest that green tea (GT) consumption may protect against cardiovascular diseases (CVDs) and different types of cancer. This effect is attributed primarily to the antioxidant properties of flavanols from GT. This review provides an overview of controlled intervention studies investigating the effect of GT consumption on antioxidant effects ex vivo and in vivo. METHODS The Medline and Cochrane databases were searched independently by two investigators for controlled intervention studies (English) on GT consumption and antioxidant effects published up to June 2010. Thirty-one studies investigating antioxidant effects ex vivo [plasma antioxidant capacity (AC), DNAs resistance against oxidative induced damage) or in vivo (lipid and protein oxidation, DNA damage] met the criteria. Results were compared by considering the participants, the dose of GT, the amount of ingested flavanols, the duration of supplementation and the investigated biomarkers. RESULTS The comparison between the studies was difficult as relevant data, e.g., on flavanol concentration in plasma (10 of 31 studies) or on major antioxidants contributing to AC, were often missing. Lipid peroxidation and DNA damage were commonly investigated. Data on protein oxidation are scarce. An antioxidant effect of at least one parameter (increase in AC or reduction of oxidative stress marker) was observed in 15 out of 22 studies by daily consumption of GT, primarily in participants exposed to oxidative stress (smokers or mixed collectives of smokers and non-smokers and physical activity) and in 6 out of 9 studies investigating the bolus consumption of GT. CONCLUSION There is limited evidence that regular consumption of GT in amounts of at least 0.6-1.5 l/day may increase AC and reduce lipid peroxidation (especially oxidation of LDL). This may contribute to the protection against CVDs and different types of cancer. Beneficial effects seem to be more likely in participants exposed to oxidative challenge.

Time to wound closure in trauma patients with disorders in wound healing is shortened by supplements containing antioxidant micronutrients and glutamine: A PRCT

BACKGROUND & AIMS : We hypothesize that wound closure in trauma patients with disorders in wound healing is accelerated by supplementation of antioxidant micronutrients and glutamine. METHODS In a randomized, double-blind, placebo-controlled trial, 20 trauma patients with disorders in wound healing were orally supplemented with antioxidant micronutrients (ascorbic acid, α-tocopherol, β-carotene, zinc, selenium) and glutamine (verum) or they received isoenergetic amounts of maltodextrine (placebo) for 14 days. Plasma/serum levels of micronutrients, glutamine, and vascular endothelial growth factor-A (VEGF-A) were determined before and after supplementation. In the wound, several parameters of microcirculation were measured. Time from study entry to wound closure was recorded. RESULTS Micronutrients in plasma/serum did not change except for selenium which increased in the verum group (1.1 ± 0.2 vs. 1.4 ± 0.2 μmol/l; P = 0.009). Glutamine decreased only in the placebo group (562 ± 68 vs. 526 ± 55 μmol/l; P = 0.047). The prevalence of hypovitaminoses and the concentration of VEGF-A did not change. Considering microcirculation, only O(2)-saturation decreased in the placebo group (56.7 ± 23.4 vs. 44.0 ± 24.0 [arbitrary units]; P = 0.043). Wound closure occurred more rapidly in the verum than in the placebo group (35 ± 22 vs. 70 ± 35 d; P = 0.01). CONCLUSIONS Time to wound closure can be shortened by oral antioxidant and glutamine containing supplements in trauma patients with disorders in wound healing.

Efficacy of vitamin supplementation in situations with wound healing disorders: results from clinical intervention studies.

Purpose of reviewThis review evaluates the efficacy of vitamin supplementations for prevention and treatment of pressure ulcer and surgical wounds on the basis of recent clinical intervention studies. Recent findingsIntervention studies show that an energy and protein-rich oral nutritional supplement providing high doses of vitamin C and zinc in combination with arginine may prevent the development of pressure ulcers. This measure seems to improve the healing of pressure ulcer, which is questionable for vitamin C alone. For surgical wounds, data from randomized controlled studies are scarce, but results on the use of vitamin C in combination with pantothenic acid are promising. SummaryConsiderable evidence suggests that supplementation of vitamin C together with zinc by an oral nutritional supplement rich in energy, protein and arginine may be an efficient tool for pressure ulcer healing in contrast to single vitamin C. The evidence for prevention of pressure ulcer by such an oral nutritional supplement is comparably low. This fits also for single vitamin C supplementation in the healing of surgical wounds. Further, well designed and well powered studies on the benefit of antioxidant vitamins for wound healing within a diet providing adequate energy and protein are necessary.

Bolus ingestion of white and green tea increases the concentration of several flavan‐3‐ols in plasma, but does not affect markers of oxidative stress in healthy non‐smokers

White tea (WT) is rich in flavan-3-ols as green tea (GT) and might provide health protective effects due to the strong antioxidant properties of flavan-3-ols. Since intervention studies with WT are lacking, we evaluated the effects of WT consumption on antioxidant status, antioxidant capacity and biomarkers of oxidative stress compared to water and GT. After an overnight fast, 70 healthy non-smokers were randomized to consume 600 mL of WT, GT or water (control). Plasma (epi-)catechin and epi(gallo)catechingallate, antioxidant capacity (Folin assay, trolox equivalent antioxidant capacity test), 8-iso-prostaglandin F(2α), ascorbic acid and uric acid were determined before and several times within 8 h after consumption. DNA strand breaks were measured in vivo and ex vivo (H(2)O(2) stimulation) in leukocytes. Plasma flavan-3-ols significantly increased after WT and GT ingestion. Trolox equivalent antioxidant capacity was lower after 5 h in controls versus WT (p = 0.031) and GT (p = 0.005). Folin-Ciocalteu reducing capacity, ascorbic and uric acid as well as markers of oxidative stress (8-iso-prostaglandin-F(2α), DNA strand breaks) were not affected by the beverages. A short-term increase of catechins does not change plasma antioxidant capacity in healthy subjects. Conclusions with respect to health protective effects of WT and GT on the basis of these biomarkers can, thus, not be drawn.

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

As nutrition-related chronic diseases have become more and more frequent, the importance of dietary prevention has also increased. Dietary fat plays a major role in human nutrition, and modification of fat and/or fatty acid intake could have a preventive potential. The aim of the guideline of the German Nutrition Society (DGE) was to systematically evaluate the evidence for the prevention of the widespread diseases obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease (CHD), stroke, and cancer through the intake of fat or fatty acids. The main results can be summarized as follows: it was concluded with convincing evidence that a reduced intake of total and saturated fat as well as a larger intake of polyunsaturated fatty acids (PUFA) at the expense of saturated fatty acids (SFA) reduces the concentration of total and low-density lipoprotein cholesterol in plasma. Furthermore, there is convincing evidence that a high intake of trans fatty acids increases risk of dyslipoproteinaemia and that a high intake of long-chain polyunsaturated n-3 fatty acids reduces the triglyceride concentration in plasma. A high fat intake increases the risk of obesity with probable evidence when total energy intake is not controlled for (ad libitum diet). When energy intake is controlled for, there is probable evidence for no association between fat intake and risk of obesity. A larger intake of PUFA at the expense of SFA reduces risk of CHD with probable evidence. Furthermore, there is probable evidence that a high intake of long-chain polyunsaturated n-3 fatty acids reduces risk of hypertension and CHD. With probable evidence, a high trans fatty acid intake increases risk of CHD. The practical consequences for current dietary recommendations are described at the end of this article.

Kinetics of l-Theanine Uptake and Metabolism in Healthy Participants Are Comparable after Ingestion of l-Theanine via Capsules and Green Tea

L-Theanine, an amino acid in green tea, is suggested to improve cognition and mood. Therefore, L-theanine is available as a supplement and is now used as an ingredient in functional drinks. Because data on the metabolic fate of L-theanine from human studies are lacking, we investigated the kinetics of L-theanine uptake and its metabolites, ethylamine and glutamic acid, in healthy participants. Within a randomized crossover study, 12 participants ingested a bolus of 100 mg L-theanine via capsules or green tea. On further occasions, 3 participants received 50 and 200 mg L-theanine via capsules. Blood and urine were collected before and up to 24 h postconsumption to determine the concentrations of L-theanine, proteinogenic amino acids, and ethylamine in plasma, erythrocytes, and urine by HPLC. L-Theanine increased in plasma, erythrocytes, and urine with comparable results after both treatments. The maximum plasma concentration of L-theanine occurred 0.8 h after intake of 100 mg L-theanine via capsules (24.3 ± 5.7 μmol/L) and tea (26.5 ± 5.2 μmol/L), respectively. The AUC of L-theanine in plasma increased dose dependently after intake of 50, 100, and 200 mg L-theanine via capsules. Moreover, ethylamine and glutamic acid increased in plasma and were excreted by urine after intake of capsules and tea. In conclusion, L-theanine is rapidly absorbed and seems to be hydrolyzed to ethylamine and glutamic acid. A minor part of L-theanine is retained in erythrocytes. Kinetics and urinary excretion of L-theanine, ethylamine, and glutamic acid are comparable after both treatments. Thus, functional effects of L-theanine intake may result from L-theanine, ethylamine, or glutamic acid.

Antioxidant effects of cocoa and cocoa products ex vivo and in vivo: is there evidence from controlled intervention studies?

Purpose of reviewThere is strong epidemiological evidence that the consumption of flavanol-rich cocoa products contributes to the prevention of cardiovascular diseases mediated partly by their strong antioxidant effects. We reviewed the recent literature to answer the question whether this antioxidant action can be confirmed by intervention studies in healthy study participants and specific patient groups. Recent findingsIn 19 controlled intervention studies (two in patients with cardiovascular diseases), markers of plasma antioxidant capacity and oxidative stress were analyzed after bolus and/or regular cocoa consumption. In both, healthy study participants and patients, total plasma antioxidant capacity as well as most markers of oxidative stress were not influenced by the intervention. Low-density lipoprotein oxidation ex vivo and in vivo decreased probably due to a direct beneficial effect of cocoa flavanols on lipid and protein oxidation. SummaryRecent clinical trials do not provide sufficient evidence for an essential contribution of cocoa products to the overall antioxidant defense. Any recommendations for cocoa intake within preventive and therapeutic measures are presently not reasonable.