Understanding Polyphenols

polyphenols 2

“Let food be thy medicine and medicine be thy food.”


Choosing a healthy diet is the greatest goal for health. Antioxidants are often discussed; however, do we understand what they are and the critical role they play?

Antioxidants are chemicals that interact with and neutralize free radicals thus preventing them from causing damage.  The body makes antioxidants but it heavily relies on external sources such as diet to obtain the rest of the antioxidants.  The most abundant type of antioxidants are polyphenols. These are secondary metabolites of plants and are involved in defense against UV radiation or aggression by pathogens. In food, polyphenols contribute to bitterness, astringency, color, flavor, odor, and oxidative stability.

Classes of polyphenols

  1. Phenolic acids such as caffeic acid highly present in coffee and ferulic acid which is abundant in cereal grains
  2. Flavonoids are the most ubiquitous form of flavonoids and the common examples are quercetin and kaempferol
    • Flavones are mainly found in parsley and celery.  Also present in cereals such as millet and wheat.  Luteolin and apigenin are among the existing forms of flavones
    • Flavanones are present in tomatoes and certain aromatic plants such as mint but high concentrations are in citrus fruits for example hesperetin in orange
    • Isoflavones possess structural similarities to estrogen.  High amounts are found in legumes with the main source being soya
  3. Stilbenes are found in low quantities in the diet and one such example is resveratrol in blueberries, grapes, mulberries and peanuts
  4. Lignans are highly concentrated in linseeds

Inadequate intake of polyphenols does not result in specific deficiency diseases, an adequate intake is encouraged because of the health benefits conferred when it comes to chronic diseases such as cancer, cardiovascular diseases, diabetes, osteoporosis, and neurogenerative disease.

Type of disease Evidence of effects
Neurodegenerative diseases Curcumin, resveratrol, and catechins (like epigallocatechin gallate (EGCG)) may protect against Alzheimer’s-like diseases and dementia through antioxidant and immunomodulatory and scavenging properties that protect neurons and inhibition of the neurotoxic effects of the beta-amyloid protein, the accumulation of which is linked to Alzheimer’s disease. The iron-chelating effects of EGCG, curcumin, myricetin, ginsenosides, and ginkgetin are thought to be an underlying mechanism through which polyphenols prevent neurotoxicity, leading to a neuroprotective effect against neurodegenerative diseases like Parkinson’s Disease, Alzheimer’s Disease, and Huntington’s Disease
Inflammation Phenolic compounds may prevent systemic and/or localized inflammation by restoring the redox balance to reduce oxidative stress, and by modulating inflammatory responses through mitigation of cytokine pathways
Cancer Flavonoids such as anthocyanins, catechins, flavanols, flavones, flavanones, and isoflavones, may neutralize free radicals and decrease cancer risk by arresting cellular growth in tumors Specific types of cancers with evidence of beneficial effects from polyphenols include colon, prostate, epithelial, endometrial, and breast cancer  
Cardiovascular health Flavonoid-rich foods have been associated with improved ventricular health, reduced platelet activity, enzymatic modulation, anti-inflammatory effects, and lower blood pressure, to increase overall vascular health   Flavonoids and resveratrol may block cholesterol oxidation to reduce LDL and lower risk of cardiovascular disease  
Type 2 diabetes Several polyphenolic compounds, anthocyanins being the most substantiated, are associated with both the prevention and management of type 2 diabetes through the protection of beta cells from glucose toxicity, anti-inflammatory, and antioxidant effects, slowing of starch digestion, and regulation and altered transport of glucose, leading to better glycemic control
Obesity Polyphenols like catechins, resveratrol, and curcumin are associated with anti-obesogenic effects, potentially through adipocyte oxidation, inhibition of lipogenesis, reduction in inflammation, and increases in energy expenditure leading to improved weight loss and maintenance. Several polyphenols have been shown to have protein-binding properties that can inhibit starch, lipid, and protein digestion in the gastrointestinal tract by interacting with and inhibiting digestive enzymes  

Polyphenol intake is dependent on dietary habits and preference.  However, bioavailability is affected by several factors.

External factors Environmental factors (i.e., sun exposure, degree of ripeness); food availability
Food processing-related factors Thermal treatments; homogenization; lyophilization; cooking and methods of culinary preparation; storage
Food-related factors Food matrix; the presence of positive or negative effectors of absorption (i.e., fat, fiber)
Interaction with other compounds Bonds with proteins (i.e., albumin) or with polyphenols with a similar mechanism of absorption
Polyphenols related factors Chemical structure; concentration in food; amount introduced
Host related factors Intestinal factors (i.e., enzyme activity; intestinal transit time; colonic microflora).
Systemic factors (i.e., gender and age; disorders and/or pathologies; genetics; physiological condition)

Nutrition is a cardinal element in disease prevention and management.  Polyphenols play a great role in curbing diseases.  To get the full benefits, daily eat 5 portions of diverse fruits and vegetables, minimize cooking of vegetables (for those that can be eaten raw consider eating them raw and steam), use herbs and spices, incorporate finger millet (wimbi), Chapati Afya and enjoy our wide range of herbal infusions. 


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