raspberry ketone in management of obesity

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Raspberry ketone is an ingredient found in raspberries (Rubus idaeus) that may have weight loss potential given preliminary findings in rodents and cell cultures, i.e. prevention of weight gain during a high-fat diet, and enhanced norepinephrine-lipolysis, increased adiponectin expression, and translocation of hormone-sensitive lipase in adipocytes (1,2). A more recent study found that raspberry ketone was protective against non alcoholic fatty liver in rats fed with a high fat diet (3).

  • raspberry ketone (4-(4-hydroxyphenyl) butan-2-one; RK) is a major aromatic compound of red raspberry (Rubus idaeus)
    • the structure of RK is similar to the structures of capsaicin and synephrine, compounds known to exert anti-obese actions and alter the lipid metabolism

Evidence for efficacy for weight loss in humans:

Prograde Metabolism (METABO) is a multi-ingredient dietary supplement that contains primarily raspberry ketone, caffeine, capsaicin, garlic, ginger and Citrus aurantium and is suggested to be used in combination with an exercise and nutrition program

  • in humans, oral ingestion of certain capsaicinoids, (active component of chilli peppers from the genus Capsicum) has been shown to increase energy expenditure, lipolysis and fat oxidation, activate brown adipose tissue and stimulate the systemic release of norepinephrine
  • bioactive compounds found in the rhizomes of ginger (Zingiber officinale) and garlic (Allium sativum) extracts have been shown to influence many key features of the metabolic syndrome by modulating adipocytokine secretion from adipose tissue, reducing body fat accumulation, decreasing circulating insulin and markers of systemic inflammation in murine and cell culture models, with similar findings emerging from studies in humans
  • extracts of Citrus aurantium, standardized for p-synephrine and other bioactive amines have been shown to increase resting metabolic rate and enhance weight loss in human clinical trials
  • in an eight week randomised controlled trial,METABO administration (2 capsules at breakfast and 2 capsules at lunchtime) was a safe and effective adjunct to an eight-week diet and exercise weight loss program by augmenting improvements in body composition, waist and hip girth. Adherence to the eight-week weight loss program also led to beneficial changes in body fat in placebo group (4)
    • of the 45 subjects who completed the study, significant differences were observed in:
      • body weight (METABO -2.0% vs. placebo -0.5%, P < 0.01), fat mass (METABO -7.8 vs. placebo -2.8%, P < 0.001), lean mass (METABO +3.4% vs. placebo +0.8%, P < 0.03), waist girth (METABO -2.0% vs. placebo -0.2%, P < 0.0007), hip girth (METABO -1.7% vs. placebo -0.4%, P < 0.003), and energy levels per anchored visual analogue scale (VAS) (METABO +29.3% vs. placebo +5.1%, P < 0.04)
    • during the first 4 weeks, effects/trends for maintaining elevated serum leptin (P < 0.03) and decreased serum resistin (P < 0.08) in the METABO group vs. placebo were also observed. No changes in systemic hemodynamics, clinical blood chemistries, adverse events, or dietary intake were noted between groups

Conclusion:

  • there is evidence for the prevention of weight gain and protection against development of non-alcoholic fatty liver in rodents fed with a high-fat diet. In humans there is minimal study evidence but the 8 week study using a preparation containing raspberry ketone (METABO) augmented improvements in body composition, waist and hip girth
  • "...although this research seems to confirm earlier results suggesting that raspberry ketone may offer some protection against obesity, health and nutrition practitioners urge clients to be wary of the newfound popularity of the supplement until more research is available.." (5)

Reference:

Last reviewed 05/2021

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