Dietary strawberries increase the proliferative response of CD3/CD28-activated CD8⁺ T cells and the production of TNF-α in lipopolysaccharide-stimulated monocytes from obese human subjects

Strawberry (Fragaria x Ananassa) intake on human health and disease outcomes: a comprehensive literature review

Strawberries provide a number of potential health promoting phytonutrients to include phenolics, polyphenols, fiber, micronutrients and vitamins. The objective of this review is to provide a comprehensive summary of recent human studies pertaining to the intake of strawberry and strawberry phytonutrients on human health. A literature search conducted through PubMed and Cochrane databases consolidated studies focusing on the effects of strawberry intake on human health. Articles were reviewed considering pre-determined inclusion and exclusion criteria, including experimental or observational studies that focused on health outcomes, and utilized whole strawberries or freeze-dried strawberry powder (FDSP), published between 2000-2023. Of the 60 articles included in this review, 47 were clinical trials, while 13 were observational studies. A majority of these studies reported on the influence of strawberry intake on cardiometabolic outcomes. Study designs included those examining the influence of strawberry intake during the postprandial period, short-term trials randomized with a control, or a single arm intake period controlling with a low polyphenolic diet or no strawberry intake. A smaller proportion of studies included in this review examined the influence of strawberry intake on additional outcomes of aging including bone and brain health, and cancer risk. Data support that the inclusion of strawberries into the diet can have positive impacts during the postprandial period, with daily intake improving outcomes of lipid metabolism and inflammation in those at increased cardiovascular risk.

Dietary foods containing nitric oxide donors can be early curators of SARS-CoV-2 infection: A possible role in the immune system

Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is a lethal virus that causes COVID-19 (Coronavirus disease 2019), the respiratory illness that has caused the COVID-19 pandemic. Even though multiple pharmacological trials are ongoing, there is no proof that any treatment will effectively cure or prevent COVID-19. Currently, COVID-19-infected patients are being managed with non-specific medications to suppress the symptoms and other associated co-morbidities. Nitric oxide is a bio-signaling molecule that has been shown to be effective for treating several viral infections in humans. Household Natural foods rich in nitrites and nitrates (NO donors) have been scientifically proven to have therapeutic benefits against immune-related respiratory tract infections. It was understood that NO could inhibit the early stage of SARS CoV-2 invasion into the human cell. Fruits and vegetables containing nitrites and nitrates have been revised and are now thought to be potential anti-CoV agents for effective control of other associated systemic disorders. The purpose of this review is to highlight some key facts about the treatment and prevention of COVID-19 infection with foods rich in nitric oxide and its donors. PRACTICAL APPLICATIONS: Improving the body's immune system is the early step to be considered as a preventive measure to stop the spreading of COVID-19 infection. Emerging research continues to mount that dietary nitrates/nitrites from plant foods are being healthy as well as keep us away from infectious diseases. They are now incorporated into low-risk adjuvant therapy for various infections and systemic disorders. This concept portrays the regular consuming foods such as fruits and vegetables that are rich in nitric oxide which have the potential to promote health, improve general well-being, and reduce the risk associated with the highly contagious diseases. Hence, we recommend adding nitrates and nitrites-containing food to the regular diet to improve the self-immunity as well as to fight against COVID-19 disease.

Daily apple consumption reduces plasma and peripheral blood mononuclear cell-secreted inflammatory biomarkers in adults with overweight and obesity: a 6-week randomized, controlled, parallel-arm trial

BACKGROUND

Obesity-associated low-grade inflammation contributes to the development of cardiovascular disease (CVD). Apples are rich in anti-inflammatory bioactives including polyphenols and fiber.

OBJECTIVES

We aimed to determine the effects of regular apple consumption on fasting plasma biomarkers of inflammation (primary outcome), endotoxemia, carbohydrate and lipid metabolism (glucose, insulin, triacylglycerol; secondary outcomes), and peripheral blood mononuclear cell (PBMC)-secreted cytokines (secondary outcome) in individuals with overweight and obesity.

METHODS

A randomized, controlled, parallel-arm trial was conducted with n = 46 participants. After avoiding foods and beverages rich in polyphenols and fiber for 2 wk, participants consumed 3 whole Gala apples (∼200 g edible parts)/d as part of their habitual diet (n = 23) or avoided apples (control, n = 23) for 6 wk. All participants limited consumption of polyphenols and fiber during the 6-wk trial. Fasting blood samples were collected before and after 6 wk for analysis of plasma biomarkers and isolation of PBMCs, which were cultured for 24 h unstimulated or stimulated with LPS (10 ng/mL).

RESULTS

Forty-four participants completed the trial (30 female, 14 male; mean ± SEM age: 45.4 ± 2.2 y; BMI: 33.4 ± 0.9 kg/m2). After ANCOVA and correcting for multiple comparisons, apples decreased fasting plasma C-reactive protein by 17.0% (range: 14.3%-19.6%, P = 0.005), IL-6 by 12.4% (range: 6.7%-17.5%, P < 0.001), and LPS-binding protein by 20.7% (range: 14.1%-26.4%, P < 0.001) compared with control. Apples also decreased PBMC-secreted IL-6 by 28.3% (range: 22.4%-33.5%, P < 0.001) and IL-17 by 11.0% (range 5.8-15.6%, P = 0.003) in the unstimulated condition compared with control. Exploratory analysis showed apples also increased plasma total antioxidant capacity by 9.6% (range: 1.7-18.9%, P = 0.002) compared with control. However, apples had no effect on anthropometric or other CVD risk markers.

CONCLUSIONS

Six-week daily whole Gala apple consumption may be an effective dietary strategy to mitigate the obesity-associated inflammation that exacerbates CVD risk, without weight loss. This trial was registered at clinicaltrials.gov as NCT03523403.

Influence of daily fresh pear consumption on biomarkers of cardiometabolic health in middle-aged/older adults with metabolic syndrome: a randomized controlled trial

Previous research suggests potential for fresh pears as a functional food for promoting cardiometabolic health. The purpose of this randomized, open-label, placebo-controlled, crossover clinical trial was to evaluate the influence of daily fresh pear consumption on blood pressure (primary outcome) and other biomarkers of cardiometabolic health in middle-aged/older adults with metabolic syndrome (MetS). Forty men and women aged 45-65 years with MetS were included and randomly assigned to receive either two medium-sized fresh pears (Pear) or a calorie-matched control drink (Control) per day for each 12-week treatment period, each separated by a 4-week washout period. After 12 weeks of daily fresh pear consumption, systolic blood pressure tended to be reduced (130 ± 2 mmHg vs. 134 ± 2 mmHg at baseline, P = 0.07) and pulse pressure was significantly reduced (51 ± 1 vs. 54 ± 1 at baseline, P < 0.05). At 12 weeks, leptin concentrations were lower in the Pear group than Control (52.5 [7.6, 120.5] ng dL-1vs. 53.4 [5.0, 120.5] ng dL-1, respectively, P < 0.05), and there was a significant group by time interaction (P < 0.05). Leptin concentrations were significantly reduced at 12 weeks compared to baseline in the Pear group (52.5 [7.6, 120.5] ng dL-1vs. 54.8 [6.4, 120.5] ng dL-1 at baseline, P < 0.05) but not in the Control group. Waist circumference was significantly reduced at 12 weeks in the Pear group (107.7 ± 2.0 cm vs. 108.4 ± 2 cm at baseline, P < 0.05) with a trend for a group by time interaction (P < 0.1), and significantly lower in the Pear group than Control (108.1 ± 2.0 cm vs. 108.8 ± 2 cm, P < 0.05) at 6 weeks with a significant group by time interaction (P < 0.05). Conversely, values were significantly increased at 6 weeks (108.8 ± 2 cm vs. 108.3 ± 2.0 cm at baseline, P < 0.05) in the Control group and sustained at 12 weeks. Waist-to-hip ratio was significantly reduced (0.92 ± 0.01 vs. 0.93 ± 0.01 at baseline, P < 0.05) at 12 weeks in the Pear group, and significantly lower than Control at 6 weeks (0.93 ± 0.01 vs. 0.93 ± 0.01, respectively, P < 0.05) and 12 weeks (0.92 ± 0.01 vs. 0.93 ± 0.01, P < 0.05). These findings suggest that daily fresh pear consumption may promote modest improvements in cardiometabolic health in middle-aged/older adults with MetS. This trial was registered at clinicaltrials.gov as NCT02228837.

Effects of fruit and vegetable consumption on inflammatory biomarkers and immune cell populations: a systematic literature review and meta-analysis

BACKGROUND

Inflammation is associated with an increased risk of a range of chronic diseases. A diet high in fruit and vegetables may help to reduce inflammation, as fruit and vegetables are rich sources of antioxidants and other biologically active substances, which may improve immune function.

OBJECTIVE

To summarize the evidence, we executed a systematic review and meta-analysis examining the effects of fruit and/or vegetable intake on inflammatory biomarkers and immune cells in humans with different diseases and conditions.

Design

Electronic databases including PubMed, Cochrane, CINAHL, and EMBASE were systematically searched up to March 2018.

RESULTS

Eighty-three studies were included. Of these, 71 (86%) were clinical trials, and 12 were observational studies (n = 10 cross-sectional and n = 2 cohort). Amongst the observational research, n = 10 studies found an inverse association between intakes of fruit or vegetables and inflammatory biomarkers. Similarly, the majority of the intervention studies (68%, n = 48) reported beneficial effects of fruit or vegetable intake on ≥1 biomarker of systemic or airway inflammation. A meta-analysis of included studies showed that fruit or vegetable intake decreased circulating levels of C-reactive protein and tumor necrosis factor-α (P < 0.05) and increased the γδ-T cell population (P < 0.05).

Conclusions

In conclusion, this review suggests that higher intakes of fruit and vegetables lead to both a reduction in proinflammatory mediators and an enhanced immune cell profile.

Increased cytokine production by monocytes from human subjects who consumed grape powder was not mediated by differences in dietary intake patterns

Recently, in a randomized, double-blind crossover study, we reported that consumption of grape powder by obese human subjects increased the production of the proinflammatory cytokines interleukin (IL)-1β and IL-6 by peripheral blood monocytes after ex vivo stimulation with bacterial lipopolysaccharide compared with the placebo treatment. We hypothesized that dietary grape powder increased the production of these cytokines by stimulated monocytes. To test this hypothesis, we used 24-hour dietary recall data to determine if differences in dietary patterns played a role in increased cytokine production. No differences in total energy, protein, carbohydrates, or fat intake in the diets were observed between the grape powder and placebo intervention periods. There were no differences observed in consumption of meats and poultry, eggs, fish, vegetables, grains, total dairy, or nuts and seeds by the participants between the 2 intervention periods. When participants received the grape powder, the recall data showed decreased intakes of butyric and capric acids (P<.05), and a possible trend toward decreased intake of cheese and total fruit (P<.1). Positive associations between the intakes of margaric acid, butter, total dairy, or whole grain and IL-6 production were observed (P<.05). However, path analysis showed that total energy, protein, carbohydrates, and fats, and individual fatty acids did not influence the production of cytokines by monocytes. The path analysis indicated that the increased cytokine production by lipopolysaccharide-stimulated monocytes from obese human subjects was caused by the grape powder and not mediated by differences in dietary intake.

Effects of daily blueberry consumption on circulating biomarkers of oxidative stress, inflammation, and antioxidant defense in postmenopausal women with pre- and stage 1-hypertension: a randomized controlled trial

Blueberries may attenuate accelerated age-related chronic disease development in postmenopausal women.

Promising Health Benefits of the Strawberry: A Focus on Clinical Studies

The potential health benefits associated with dietary intake of fruits have attracted increasing interest. Among berries, the strawberry is a rich source of several nutritive and non-nutritive bioactive compounds, which are implicated in various health-promoting and disease preventive effects. A plethora of studies have examined the benefits of strawberry consumption, such as prevention of inflammation disorders and oxidative stress, reduction of obesity related disorders and heart disease risk, and protection against various types of cancer. This review provides an overview of their nutritional and non-nutritional bioactive compounds and which factors affect their content in strawberries. In addition, the bioavailability and metabolism of major strawberry phytochemicals as well as their actions in combating many pathologies, including cancer, metabolic syndrome, cardiovascular disease, obesity, diabetes, neurodegeneration, along with microbial pathogenesis have been reviewed, with a particular attention to human studies.

Dietary supplementation with purified citrus limonin glucoside does not alter ex vivo functions of circulating T lymphocytes or monocytes in overweight/obese human adults

Overweight/obesity is associated with chronic inflammation and impairs both innate and adaptive immune responses. Limonoids found in citrus fruits decreased cell proliferation and inflammation in animal studies. We hypothesized that limonin glucoside (LG) supplementation in vivo will decrease the ex vivo proliferation of T cells and the production of inflammatory cytokines by monocytes and T cells. In a double-blind, randomized, cross-over study, 10 overweight/obese human subjects were served purified LG or placebo drinks for 56 days each to determine the effects of LG on immune cell functions. The percentage of CD14+CD36+ cells in whole blood was analyzed by flow cytometry. Peripheral blood mononuclear cells were isolated and activated with CD3 plus CD28 antibodies (T-lymphocyte activation) or lipopolysaccharide (monocyte activation). Interferon γ, tumor necrosis factor α, interleukin (IL) 2, IL-4, and IL-10 were measured in supernatants from activated T cells. Supernatants from activated monocytes were analyzed for the production of tumor necrosis factor α, IL-1β, and IL-6. Peripheral blood mononuclear cells were prestained with PKH dye and activated with CD3 plus CD28 antibodies to determine the proliferative responses of CD4+ and CD8+ T lymphocytes by flow cytometry. No differences were observed for CD14+CD36+ monocyte populations, T-cell proliferation, or the production of T cell and monocyte cytokines between the 2 treatments. Thus, LG supplementation in vivo did not affect ex vivo functions of T cells and monocytes, whereas it decreased several circulating markers of hepatic inflammation as we previously reported.

Dietary grape powder increases IL-1β and IL-6 production by lipopolysaccharide-activated monocytes and reduces plasma concentrations of large LDL and large LDL-cholesterol particles in obese humans

Obese individuals are at an increased risk of developing CVD, hypertension, type 2 diabetes, and bacterial and viral infections when compared with the normal-weight population. In a 9-week randomised, double-blind, cross-over study, twenty-four obese subjects aged between 20 and 60 years and with a BMI between 30 and 45 kg/m2were fed grape or placebo powder for 3-week intervals to determine the effects of dietary grapes on blood lipid profiles, plasma inflammatory marker concentrations and immune cell function. Blood samples were collected on days 1 and 8 for obtaining baseline information and at weeks 3, 4, 8 and 9. Comprehensive chemistry panels, lipid profile analyses by NMR, measurement of plasma inflammatory marker concentrations, and analyses of cytokine production by activated T lymphocytes and monocytes were performed for each blood draw. Dietary grape powder reduced the plasma concentrations of large LDL-cholesterol and large LDL particles compared with the placebo powder (P< 0·05). The concentrations of interferon-γ, TNF-α, IL-4 and IL-10 were measured in supernatants from peripheral blood mononuclear cells (PBMC) activated with anti-CD3/CD28 antibodies and those of TNF-α, IL-1β, IL-6 and IL-8 were measured in supernatants from PBMC activated with lipopolysaccharide (LPS). No difference in the production of T-cell cytokines was observed between the two intervention groups. The production of IL-1β and IL-6 was increased in supernatants from LPS-activated PBMC in the grape powder group compared with the placebo powder group (P< 0·05). These data suggest that dietary grapes may decrease atherogenic lipid fractions in obese individuals and increase the sensitivity of monocytes in a population at a greater risk of developing infections.

Non-alcoholic fatty liver disease, diet and gut microbiota

Non-alcoholic fatty liver disease (NAFLD) is a severe liver disease that is increasing in prevalence with the worldwide epidemic of obesity and its related insulin-resistance state. Evidence for the role of the gut microbiota in energy storage and the subsequent development of obesity and some of its related diseases is now well established. More recently, a new role of gut microbiota has emerged in NAFLD. The gut microbiota is involved in gut permeability, low-grade inflammation and immune balance, it modulates dietary choline metabolism, regulates bile acid metabolism and produces endogenous ethanol. All of these factors are molecular mechanisms by which the microbiota can induce NAFLD or its progression toward overt non-alcoholic steatohepatitis. Modification of the gut microbiota composition and/or its biochemical capacity by specific dietary or pharmacological interventions may advantageously affect host metabolism. Large-scale intervention trials, investigating the potential benefit of prebiotics and probiotics in improving cardiometabolic health in high-risk populations, are fervently awaited.