The Effects of Grapefruit on Weight and Insulin Resistance: Relationship to the Metabolic Syndrome

Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States
Journal of Medicinal Food (Impact Factor: 1.63). 02/2006; 9(1):49-54. DOI: 10.1089/jmf.2006.9.49
Source: PubMed


To study the effects of grapefruit and grapefruit products on body weight and metabolic syndrome, 91 obese patients were randomized to either placebo capsules and 7 ounces (207 mL) of apple juice, grapefruit capsules with 7 ounces (207 mL) of apple juice, 8 ounces (237 mL) of grapefruit juice with placebo capsule, or half of a fresh grapefruit with a placebo capsule three times a day before each meal. Metabolic syndrome parameters were measured at the beginning and end of 12 weeks. After 12 weeks, the fresh grapefruit group had lost 1.6 kg, the grapefruit juice group had lost 1.5 kg, the grapefruit capsule group had lost 1.1 kg, and the placebo group had lost 0.3 kg. The fresh grapefruit group lost significantly more weight than the placebo group (P < .05). A secondary analysis of those with the metabolic syndrome in the four treatment groups demonstrated a significantly greater weight loss in the grapefruit, grapefruit capsule, and grapefruit juice groups compared with placebo (P < .02). There was also a significant reduction in 2-hour post-glucose insulin level in the grapefruit group compared with placebo. Half of a fresh grapefruit eaten before meals was associated with significant weight loss. In metabolic syndrome patients the effect was also seen with grapefruit products. Insulin resistance was improved with fresh grapefruit. Although the mechanism of this weight loss is unknown it would appear reasonable to include grapefruit in a weight reduction diet.

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    • "Several pharmacological properties have been attributed to various members of the citrus species, ranging from anticancer, (Jacob et al., 2000; Silalahi, 2002; Enterazi et al., 2009) antimicrobial, (Nannapaneni et al., 2008; Tao et al., 2009; Dhanavade et al., 2011; Kumar et al., 2011; Lawal et al., 2012), antifungal, (Valezquez-Nunez et al., 2013) antityphoid, (Kumar et al., 2011 ), antioxidant, (Chodak and Tarko, 2007 ), antiinflammatory , (Galati, 1994; Karaca et al., 2008), antiulcer, (Nagaraju et al., 2012), hypolipidemic (Khan et al., 2010), hepatoprotective (Karaca et al., 2008; Kangralkar et al., 2009) and antidiabetic, (Daniels, 2006; Parmar and Kar, 2007), among others. The peels of the citrus fruits, especially grapefruit and bitter orange, which are rich in flavonoid glycosides, polyphenols and volatile oils have been used in several cultures for weight control, amongst other pharmacological uses (Fujioka et al., 2006; Stohs and Shara, 2007). Previous studies have demonstrated the effects of these flavonoids on lipid and glucose metabolism in experimental animals and humans (Jung, 2004; Miwa, 2005), specifically on lipid catabolism, glucose transport, the insulin-receptor function, and peroxisome proliferator-activated receptors (PPARs) activation, all of which play essential roles in weight control (Shisheva, 1992; Liang, 2001; Kim, 2003; Lee, 2003). "

    Full-text · Article · Oct 2015
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    • "While subjects in one RCT (Dow et al., 2012) had a three-week wash-out, participants in another RCT (Silver et al., 2011) underwent a two-week run-in. One RCT (Fujioka et al., 2006) did not report any pretrial regimen. Participants in two RCTs (Dow et al., 2012; Silver et al., 2011) had their diets restricted and analysed daily caloric intakes using the University of Minnesota Nutrition Data System for Research software; while those in the third RCT (Fujioka et al., 2006) continued their usual diet with no report on how caloric intake was analysed. "
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    ABSTRACT: The aim of this systematic review was to evaluate the evidence for or against the effectiveness of grapefruits (Citrus paradisi) on body weight, blood pressure and lipid profile. Electronic searches were conducted in MEDLINE, EMBASE, AMED and the Cochrane Clinical Trials databases to identify relevant human randomized clinical trials (RCTs). Hand searches of bibliographies were also conducted. Only overweight and obese subjects were included. The reporting quality was assessed using the CONSORT checklist, and the strength of the overall body of evidence was rated based on the GRADE criteria. 154 citations were identified and three RCTs with a total of 250 participants were included. The RCTs were of moderate quality. A meta-analysis for change in body weight failed to reveal a significant difference between grapefruits and controls, MD: -0.45 kg (95% CI: -1.06 to 0.16; I(2) = 53%, but analysis revealed a significant decrease in systolic blood pressure, MD: -2.43 mmHg (95%CI: -4.77 to -0.09; I(2) = 0%). Paucity in the number of RCTs, short durations of interventions, and lack of an established minimum effective dose limit the conclusions that can be drawn about the effects of grapefruit on body weight and metabolic parameters. Further clinical trials evaluating the effects of grapefruit are warranted.
    Full-text · Article · Apr 2015 · Critical reviews in food science and nutrition
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    • "Of these, an additional 39 articles were excluded for the following reasons: 22 articles did not have the data on outcome measures, 9 articles treated the subjects with multi-component supplement, 8 articles did not report enough details of SD or baseline or endpoint or mean difference for primary or secondary outcome measures [30]–[37]. We contacted the main authors of these 8 studies by email, but only one replied and the requested data was no longer available [31]. Thus, 12 articles were finally selected for inclusion in the meta-analysis [38]–[49]. "
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    ABSTRACT: Background: Diabetes mellitus has become a worldwide health problem. Whether fruit juice is beneficial in glycemic control is still inconclusive. This study aimed to synthesize evidence from randomized controlled trials on fruit juice in relationship to glucose control and insulin sensitivity. Methods: A strategic literature search of PubMed, EMBASE, and the Cochrane Library (updated to March, 2014) was performed to retrieve the randomized controlled trials that evaluated the effects of fruit juice on glucose control and insulin sensitivity. Study quality was assessed using the Jadad scale. Weighted mean differences were calculated for net changes in the levels of fasting glucose, fasting insulin, hemoglobin A1c (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR) using fixed- or random-effects model. Prespecified subgroup and sensitivity analyses were performed to explore the potential heterogeneity. Results: Twelve trials comprising a total of 412 subjects were included in the current meta-analysis. The numbers of these studies that reported the data on fasting glucose, fasting insulin, HbA1c and HOMA-IR were 12, 5, 3 and 3, respectively. Fruit juice consumption did not show a significant effect on fasting glucose and insulin concentrations. The net change was 0.79 mg/dL (95% CI: -1.44, 3.02 mg/dL; P = 0.49) for fasting glucose concentrations and -0.74 µIU/ml (95% CI: -2.62, 1.14 µIU/ml; P = 0.44) for fasting insulin concentrations in the fixed-effects model. Subgroup analyses further suggested that the effect of fruit juice on fasting glucose concentrations was not influenced by population region, baseline glucose concentration, duration, type of fruit juice, glycemic index of fruit juice, fruit juice nutrient constitution, total polyphenols dose and Jadad score. Conclusion: This meta-analysis showed that fruit juice may have no overall effect on fasting glucose and insulin concentrations. More RCTs are warranted to further clarify the association between fruit juice and glycemic control.
    Full-text · Article · Apr 2014 · PLoS ONE
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