Effect of daily supplementation of fruits on oxidative stress indices and glycaemic status in type 2 diabetes mellitus

doi:10.1016/j.ctcp.2012.12.002

Complementary Therapies in Clinical Practice

Volume 19, Issue 2, May 2013, Pages 97-100

https://doi.org/10.1016/j.ctcp.2012.12.002 Get rights and content

Abstract

This study sought to examine whether consumption of two low-calorie fruit/day for 3-months can effectively improve oxidative stress, anthropometry, blood pressure and glycaemic control in type 2 diabetes mellitus. Study involved 123 patients who were assigned to receive either standard care or with additional dietary therapy. Dietary intervention resulted in significant reduction in malondialdehyde, plasma glucose, glycated haemoglobin and improvement in antioxidants like vitamin C and reduced glutathione when compared to controls. Mean plasma levels of vitamin C increased by 64% (p < 0.001). There were no differences in waist circumference, waist-to-hip ratio, blood pressure, vitamin E and superoxide dismutase in the intervention group at follow-up. Diet rich in fruits can improve some antioxidants which are likely to reduce oxidative stress in type 2 diabetes. Regular consumption of fruits can lower the glycaemic status in these patients. The study supports the usefulness of plasma vitamin C as a biomarker for fruit intake.

Introduction

The worldwide burden of type 2 diabetes is increasing rapidly and is projected to be atleast 366 million by the year 2030.¹ One of the pathogenic mechanisms that increase the risk for diabetes and its complications is the imbalance between pro-oxidants and antioxidants, called as oxidative stress (OST).² Hyperglycemia induced nonenzymatic glycosylation, polyol pathway, glucose auto-oxidation and monocyte dysfunction leads to continuous production of free radicals. One way of combating this increased OST would be to increase antioxidant defences. This can be achieved either by increase in dietary intake of fruits and vegetables or consumption of antioxidant supplements. Epidemiological evidence demonstrate the benefits of a diet rich in fruits, vegetables and whole grain cereals in diabetes3, 4, 5, 6 but the results are not entirely consistent. In many of the studies dietary antioxidant intake is calculated by self-reported diet questionnaires. The major drawback of food frequency questionnaires (FFQ) is that it may overestimate the fruit and vegetable consumption.⁷ This may be one of the reasons for the inconsistent associations between fruit and vegetable consumption and diabetes risk reported earlier.3, 4, 5, 6 Furthermore, intake of fruit juices are positively associated with incidence of type 2 diabetes, whereas consumption of whole fruit and vegetables are inversely associated.⁸ Whole fruits may contribute to a decreased incidence of type 2 diabetes through their low energy density, low glycaemic load and high fibre and micronutrient content.⁹ With this background in the present study we aimed to estimate the effect of 3-months dietary antioxidant intake on the levels of OST, antioxidant status, glycaemic level, anthropometry and blood pressure in type 2 diabetes mellitus.

Section snippets

Materials and methods

The participants were recruited from the outpatient diabetes clinic of Kasturba Medical College Hospital (KMCH), Mangalore. A written informed consent approved by the institutional ethical committee was collected at the beginning of the study. This study comprised of 123 type 2 diabetes patients between the ages 40–75 years, non-smokers, non-alcoholics and with no history of acute macrovascular complications, cancer, pulmonary tuberculosis or any serious systemic illness. Stratified sampling

Results

One twenty one patients completed the study. Out of the 2 drop-outs from the intervention group one moved and one withdrew from the study. Out of 58 subjects who completed the dietary intervention, 51 participants consumed two fruits on all days of the study. Remaining three subjects consumed fruits on an average of 4 days/week, two subjects for less than twice/week and two participants did not eat any fruits. With the intention-to-treat, all were included in the final analysis.

The mean (SD)

Discussion

Results of the present study show that consumption of 2 low calorie fruits per day can significantly improve vitamin C levels (64%) and bring down the OST in type 2 diabetes. In this trial, we did not use a controlled diet for the intervention. Instead, subjects remained on a self-selected diet but were instructed to consume any 2 low calorie fruit from the given fruit group. By doing so, the participants were able to follow the intervention diet during the 3-months of the study and achieve a

Conclusions

The study shows that daily consumption of two low-calorie fruits in patients with type 2 diabetes can reduce OST with appreciable improvement in antioxidants like vitamin C and reduced GSH. Our findings also suggest that vitamin C can be considered as a good biomarker to assess the fruit intake. However there was no significant improvement in vitamin E, SOD, anthropometry and BP after 3-months of fruit intake. Other than nutritional values of these fruits, they also help in reducing the

Conflict of interest statement

No potential conflicts of interest relevant to this article were reported.

Acknowledgements

This study was funded by a grant from Manipal University (431/013/2007). We would like to acknowledge the participants of the trial, who have contributed their effort and time for the trial. We are also grateful to the study dietician Divya for her dedicated assistance while delivering the dietary intervention.

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Micronutrient deficiencies, such as iron, folic acid, and vitamins C and D, are currently prevalent due to inadequate consumption of natural food sources, namely raw vegetables and fruits. This deficiency is compounded by the growing reliance on synthetic nutraceuticals and processed food, which exhibit poor absorbency within the gastrointestinal tract. Scientific studies consistently indicate that naturally prepared whole foods are superior in terms of nutrient absorption compared to processed and synthetic supplements. To address this issue, we utilized FDA-approved tragacanth gum (TG) in the synthesis of nano-nutraceuticals by encapsulating beetroot juice and ball-milled sweet basil (Ocimum basilicum). TG, in its micro or macro form, possesses the remarkable ability to form hydrogels capable of absorbing water up to 50 times its weight. However, the hydrogel-forming property diminishes when TG is reduced to the nanoscale. We effectively exploited these properties to facilitate the synthesis of nano-nutraceuticals. The procedure involved encapsulating beetroot juice and sweet basil nanopowder using TG hydrogel, followed by freeze-drying. Subsequently, the freeze-dried encapsulated TG composite was subjected to ball-milling to achieve the desired nano-nutraceuticals. These nano-nutraceuticals naturally contain essential nutrients such as iron, folic acid, ascorbic acid, chlorophyll, niacin, and sugars, without the need for chemical processing or preservatives.
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Sugar-sweetened beverages (SSBs) providing excess energy increase adiposity. The effect of other food sources of sugars at different energy control levels is unclear.
To determine the effect of food sources of fructose-containing sugars by energy control on adiposity.
In this systematic review and meta-analysis, MEDLINE, Embase, and Cochrane Library were searched through April 2022 for controlled trials ≥2 wk. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars), addition (energy from sugars added), subtraction (energy from sugars subtracted), and ad libitum (energy from sugars freely replaced). Independent authors extracted data. The primary outcome was body weight. Secondary outcomes included other adiposity measures. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence.
We included 169 trials (255 trial comparisons, n = 10,357) assessing 14 food sources at 4 energy control levels over a median 12 wk. Total fructose-containing sugars increased body weight (MD: 0.28 kg; 95% CI: 0.06, 0.50 kg; P_MD = 0.011) in addition trials and decreased body weight (MD: −0.96 kg; 95% CI: −1.78, −0.14 kg; P_MD = 0.022) in subtraction trials with no effect in substitution or ad libitum trials. There was interaction/influence by food sources on body weight: substitution trials [fruits decreased; added nutritive sweeteners and mixed sources (with SSBs) increased]; addition trials [dried fruits, honey, fruits (≤10%E), and 100% fruit juice (≤10%E) decreased; SSBs, fruit drink, and mixed sources (with SSBs) increased]; subtraction trials [removal of mixed sources (with SSBs) decreased]; and ad libitum trials [mixed sources (with/without SSBs) increased]. GRADE scores were generally moderate. Results were similar across secondary outcomes.
Energy control and food sources mediate the effect of fructose-containing sugars on adiposity. The evidence provides a good indication that excess energy from sugars (particularly SSBs at high doses ≥20%E or 100 g/d) increase adiposity, whereas their removal decrease adiposity. Most other food sources had no effect, with some showing decreases (particularly fruits at lower doses ≤10%E or 50 g/d). This trial was registered at clinicaltrials.gov as NCT02558920 (https://clinicaltrials.gov/ct2/show/NCT02558920).
Role of dietary spices in modulating inflammation and oxidative stress
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Obesity-induced oxidative stress and inflammation are strongly associated with cardiovascular disease (CVD). Accumulating evidence suggests that spices can help lower oxidative stress and inflammation, which may reduce the risk of CVD. The objective of the current review was to comprehensively summarize the findings from clinical studies that examined the antioxidative and/or antiinflammatory effects of popular and widely used spices in the United States. A systematic literature search was conducted in CINAHL, Cochrane Library, and PubMed to identify studies that investigated the effect of selected spices on markers of oxidative stress and inflammation in humans. A total of 99 eligible clinical studies were identified that examined the antioxidative and/or antiinflammatory effect of consuming Capsicum (n=2), cardamom (n=4), cinnamon (n=13), cumin (n=5), dill (n=1), fenugreek (n=4), garlic (n=20), ginger (n=21), onion (n=3), oregano (n=2), parsley (n=1), sage (n=1), sesame (n=12), turmeric (n=7), and spice blend (n=7). We found numerous studies that reported an antioxidative effect of consuming cinnamon (n=4), garlic (n=10), ginger (n=5), and sesame (n=11) and an antiinflammatory effect of consuming cinnamon (n=6), garlic (n=5), ginger (n=14), and turmeric (n=5). Few of the included studies report an antioxidative effect of consuming Capsicum (n=1), cardamom (n=2), cumin (n=3), dill (n=1), fenugreek (n=1), onion (n=2), oregano (n=1), parsley (n=1), sage (n=1), and turmeric (n=1) and an antiinflammatory effect of consuming cardamom (n=2), cumin (n=1), fenugreek (n=2), oregano (n=1), and sesame (n=2). There are no clinical studies to date that demonstrate an antiinflammatory effect of consuming Capsicum, dill, onion, parsley, and sage. In addition, several clinical studies report an antioxidative (n=2) and an antiinflammatory (n=3) effect of consuming a blend of spices given as dietary supplements or delivered in a meal. Combined, these findings suggest an antioxidative and antiinflammatory effect of several commonly used spices.
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2016, Nutrition, Metabolism and Cardiovascular Diseases
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Related to the microvascular complications of diabetes, in a post hoc analysis of a cohort of T2D in PREDIMED Study, MedD may protect against DR but not against DN [105]. Some studies in T2D showed beneficial effects on OxS markers of broccoli sprouts as a unique supplement and of low-calorie fruit consumption [106,107]. Cocoa (main components such as catechin and epicatechin) exerts an anti-inflammatory and an antioxidant effect (decreasing lipid peroxidation) [108].
The possible link between hyperglycaemia-induced oxidative stress (OxS) and diabetic complications is suggested by many in vitro studies. However, not much attention has been paid to the clinical evidence supporting this hypothesis, as well as to their possible therapeutic implications.
Some prospective studies show a direct correlation between an increase in OxS biomarkers and the appearance of diabetes complications. This is consistent with the evidence that any acute increase of glycaemia, particularly post-prandial, and hypoglycaemia causes endothelial dysfunction and inflammation, through the generation of an OxS. However, the detection of free radicals is difficult as they are highly reactive molecules with a short half-life. Instead, the metabolites of OxS are measured. Interventional trials with supplemented antioxidants have failed to show any beneficial effects. Conversely, natural foods show very promising results.
The “new antioxidant” approach includes the possibility of controlling free radical production and increasing intracellular antioxidant defence, a concept different from the old one, when antioxidant activities implied scavenging the free radicals already produced. A synergistic action in this respect could convincingly be obtained with a balanced ‘Mediterranean Diet’ (MedD) type. Early intensive glucose control is still the best strategy to avoid OxS and its associated diabetes complications.
Fruit and Glycemic Control in Type 2 Diabetes
2015, Glucose Intake and Utilization in Pre-Diabetes and Diabetes: Implications for Cardiovascular Disease
Health professionals often advise subjects with type 2 diabetes (T2D) to restrict fruit intake. We show here that there is no supportive scientific evidence for this. At least 19 studies have tested intake of fruit on postprandial glucose in T2D. Only two long-term intervention studies have investigated the impact of fruit intake on glycemic control in T2D. The studies show that fruit has neutral or positive glycemic effects. By restraining fruit intake, T2D subjects add an additional risk of disease and premature death. Further, there is no evidence to support that fructose contained in fruit under normal conditions has deleterious health effects. In summary, we find no evidence for a negative impact of fruit on glycemic control in T2D. Subjects with T2D should eat fruit just as the general population, without fearing worsening of their glycemic control.

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Effect of daily supplementation of fruits on oxidative stress indices and glycaemic status in type 2 diabetes mellitus

Abstract

Introduction

Section snippets

Materials and methods

Results

Discussion

Conclusions

Conflict of interest statement

Acknowledgements

Prev Med

Am J Clin Nutr

Am J Clin Nutr

Anal Biochem Rev

Arch Gerontol Geriatr

Global burden of disease, diabetes mellitus

Role of oxidative stress in the etiology of type 2 diabetes and the effect of antioxidant supplementation on glycemic control

J Investig Med

Dietary factors determining diabetes and impaired glucose tolerance: a 20-year follow-up of the Finnish and Dutch cohorts of the seven countries study

Diabetes Care

A prospective study of fruit and vegetable intake and the risk of type 2 diabetes in women

Diabetes Care

Dietary assessments in the European prospective study of diet and cancer (EPIC)

Eur J Cancer Prev