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Proanthocyanidins in foods


Related terms
Author information
Proanthocyanidin content in selected foods
Theory and evidence

Related Terms
  • Adequate protein diet, Barry Sears, carbohydrate, diet, fat, low carbohydrate diet, protein.

  • The Zone diet is an unproven dietary regime, which has been popularized by Dr. Barry Sears through sales of his 1995 book, The Zone. Despite claims made in the book, there is little available research to support its overall benefit.
  • The Zone diet is a calorie-restricted diet that provides adequate protein, moderate levels of carbohydrates, essential fats and micronutrients spread through three meals and two snacks that approximately maintain the protein-to-carbohydrate ratio throughout the day.
  • Proponents believe that the Zone diet promotes optimal metabolic efficiency in the body by balancing the hormones insulin and glucagon. Insulin is responsible for converting, in the blood, incoming nutrients into cells. Glucagon regulates glucose in the liver. Overall, the Zone's food plan consists of a dietary intake of 40% carbohydrates, 30% protein and 30% fat.
  • Under this diet, recommended foods include fruits and vegetables (fresh or frozen), oatmeal (whole grain), protein powder (e.g. soybean isolate), chicken, turkey, lean beef, fish, low-fat cottage cheese, soy food, nuts (e.g. almonds, cashews, macademia, pistachios), extra virgin olive oil, natural sweeteners, such as fructose or stevia.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Cheuvront SN. The zone diet and athletic performance. Sports Med. 1999;27(4):213-228.
  2. Natural Standard: The Authority on Integrative Medicine.
  3. Sears B. The Zone Diet and athletic performance. Sports Med. 2000;29(4):289-294.

Proanthocyanidin content in selected foods

    Theory and evidence
    • A 2007 study by Du et al. observed a notable induction of antioxidant enzymes occurring in a concentration-dependent fashion when cardiac H9C2 cells were incubated with micromolar concentrations of proanthocyanidin B4 or catechin. The authors propose that proanthocyanidin B4 or catechin pretreatment reduced the accumulation of intracellular reactive oxygen species (ROS) and cardiac cell apoptosis, which was induced by xanthine oxidase (XO)/xanthine. The authors therefore propose that by inducing endogenous antioxidant enzymes, grape seed polyphenols may offer protection against cardiac cell apoptosis. This mechanism may explain the cardioprotective properties of grape seed extract.
    • A 2005 article by Erdman et al. discussed the risk and safety assessments of supporting heart health via the intake of certain flavonoids. The article also proposed several mechanisms of action for flavonoids.
    • A 2005 study by Hernandez-Vallejo et al. found that apple procyanidins are capable of reproducing the inhibition of lipoprotein secretion and cholesteryl ester synthesis. The results are similar to the mechanism of action of polyphenols that results from an impaired lipid availability. This impaired lipid availability could possibly cause intestinal lipoprotein secretion to be inhibited. It could also add to the hypolipidemic effect that these compounds have exhibited in vivo.
    • A 2003 study by Shao et al. observed an increase in cell death and reactive oxygen species generation when laboratory animals were exposed to higher concentrations of grape seed proanthocyanidin extract. The increase in cell death and reactive oxygen species was measured by lactate dehydrogenase release and propidium iodide uptake.
    • A 2002 study by Pataki et al. observed the cardioprotective effects of grape seed proanthocyanidins against reperfusion-induced injury. It was proposed that grape seed proanthocyanidins demonstrate these effects by directly or indirectly reducing or removing the free radicals that occur in the myocardium after ischemia reperfusion.
    • A 2002 study by Bagchi et al. found that proanthocyanidins derived from grape seeds demonstrate cellular protection.
    • A 2001 study by Spencer et al. found that 3'-O-methylepicatechin exerts a protective effect against stress-induced cell death. The studies described in the article also suggest that the most significant bioactive forms of procyanidins and flavanol monomers in vivo are probably the conjugates and/or metabolites of epicatechin.
    • A 2000 study by Subarnas et al. evaluated the activity of proanthocyanidins taken from the roots of Polypodium feei fern in controlling pain and reducing inflammation. The writhing response of rats to pain induced by 0.7% acetic acid was significantly reduced at doses of 50 and 100mg/kg. At the dose of 100 mg/kg, the proanthocyanidins offered pain protection at a rate of 76.23 higher than that of 59.85% acetylsalicylic acid (59.84 %) at a dose of 50 mg/kg. In a separate anti-inflammatory test, the proanthocyanidin compound significantly inhibited the rats' plantar edema, which was induced by 1% of carrageenan; however, this activity was only observable at a higher dose of 200 mg/kg. The findings of these studies suggest that proanthocyanidin from Polypodium feei roots may possess analgesic and anti-inflammatory activities. The authors suggest that the inhibition of prostaglandin biosynthesis may be the mechanism of action, because the proanthocyanidin fraction inhibited cyclooxygenase, but not 5-lypoxygenase enzymes.
    • A 1999 study by Costantini et al. found that the rapid reduction in the swelling of the lower limbs in humans, which was observed in the course of the study, can be explained by the oligomeric proanthocyanidins' mechanism of action.
    • A 1983 study by Borzeix et al. discussed the mechanism of action of procyanidolic oligomers. The authors propose that these chemicals may cause an increase in the resistance of the tight junctions in arteriolar capillaries. This action may therefore interfere with the rise in pressure that normally occurs at the time that blood is injected.

    Copyright © 2011 Natural Standard (

    The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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