There’s lots of excitement surrounding the power of polyphenols in the nutrition world right now, as compelling new evidence supports their ability to prevent and protect against degenerative diseases. We explain the science behind this in our latest blog.
A number of published studies have observed how polyphenol compounds can help to improve blood vessel function, lower inflammation, inhibit platelet aggregation (a common cause of a heart attack or stroke), have an anti-aging effect and the list goes on. Many polyphenols actually complement each other by boosting our natural immune defence system lowering our risk of disease and cognitive decline.
What are Polyphenols?
We’ve known for years that plant-based foods offer numerous health benefits due to their vitamin, mineral and fibre content, however, more advanced research has begun to identify additional compounds in certain food and beverages that exert powerful healing properties. Fruits, vegetables, coffee, tea, nuts, legumes, seeds, herbs and spices are the richest sources. The magical compounds that offer these medicinal benefits give these foods their colour and taste, as a general rule the more bitter a substance is the higher the polyphenol quantity.
Originally referred to ‘antioxidants’ or ‘phytonutrients’ the classification of these nutrients is becoming much more refined – this is to distinguish between the different chemical structures that exist between them. Polyphenols are some of the most extensively researched, grouped together due to their ring-shape and divided into four sub categories:
- Phenolic acids
- Flavonoids
- Stilbenes
- Lignins
Many foods actually contain a mixtures of polyphenols. Apples and onions in particular have a high polyphenol content so you could say “an apple or onion a day keeps the doctor away.”
How Do They Work?
The exact mechanism by which polyphenols work in the human body is still the subject of extensive scientific research. Initially it was believed the health benefits were due to their antioxidant capacity and ability to mop up free radicals and inhibit oxidative damage in the body which causes disease.
It was then observed that polyphenols exerted a more direct effect on cardiovascular health by effecting the expression of genes involved in angiogenesis (growth of new blood vessels). It seems polyphenols actually have a much more powerful ability to modulate the activity of enzymes and cell receptors and have strong implications for gene expression. In simple turns they have the ability to turn on or off the genes and the disease outcome.
Even more exciting (well for us gut obsessed Fitter Foodies) is the research suggesting polyphenols support gut health by acting as a prebiotic and increasing our levels of beneficial Lactobacillus and Bifidobacteria bacteria. There’s also evidence to suggest catechins (found in tea, chocolate, apples and blackberries) exert an antimicrobial effect inhibiting the growth and proliferation of pathogenic bacteria.
Polyphenols have to undergo a process of being hydrolysed by intestinal enzymes or metabolised by the gut flora in the colon to be absorbed. Only 5-10% of polyphenols are absorbed in the small intestine, while the rest make their way to the colon. Specific metabolites produced by the colonic microflora exert important physiological effects, for example, lignans from linseed are metabolised to produce enterolactone and enterodiol which helps to modulate levels of estrogen in the body and protect against hormonal imbalances and oestrogen related cancers.
Supplements or Food
Of course supplement companies have jumped on the band wagon. Quercetin is a polyphenol found in onions and shown to decrease inflammatory chemicals in the body. You can now buy capsules that offer 300mg+ of quercetin, a dose almost 100 times higher than would be sourced naturally from dietary intake. Whilst there maybe an argument for using supplements in therapeutic doses (guided by a qualified practitioner) sourcing from food is much more safer particularly given the exact mechanisms by which antioxidants work is still not yet fully understood.
The Devil is In The Dose
Waaaaay back in the 17th century a clever bloke called Paracelsus said:
“All substances are poisons, there is none which is not a poison. It is the dose that distinguishes a poison from a remedy.”
The same applies to antioxidants. The ability of polyphenols to interact with proteins in the body and influence the action of enzymes means there will be a sweet spot that offers the health and nutrition benefit but in excess may cause negative effects.
It’s also worth noting the additional compounds in polyphenol rich foods have the potential to impact upon our health; fruit contains fructose sugars which needs to be consumed in moderation, alcohol in red wine, aflatoxin in peanuts, fat in chocolate and the caffeine in tea and coffee can all have a negative effect on health outcomes in excess. Furthermore some polyphenol rich foods have other anti-nutritional effects, the tannins in tea, coffee and chocolate may increase the risk of iron deficiency by hindering the absorption of iron if consumed too frequently.
Your Top Polyphenol List
Here are some of the highest polyphenol foods, stick this list on your fridge and make sure you get a daily dose:
Polyphenol Tips: Favour Local and Chemical Free
Of course the ‘local’ aspect can’t apply to coffee, cocaoa, tea and some of the exotic fruits but you can make a concerted effort to buy your fruit and vegetables from local farms and eat seasonally. Environmental factors have a huge influence on the polyphenol content of foods and beverages. The soil, sun exposure, rainfall and how they are cultivated will impact upon the polyphenol content.
Those produced by organic or natural agricultural means have higher levels of polyphenols than those grown by conventional agriculture without stress. Plants produce many of these antioxidant compounds to protect themselves against predators and disease. If fertilisers, pesticides and herbicides take over this function there will naturally be lower production of protective antioxidants. There is also the added burden of agricultural chemicals to consider that may outweigh the benefit of consuming polyphenol rich foods. Sourcing foods locally and organically (or by farmers who minimise use of chemicals) will ensure you get more polyphenols for you pounds.
Polyphenol Tips: Cooking
Storage and preparation may also affect the content and availability of polyphenols compounds. Many antioxidants are present in the in the outer parts of fruits and vegetables like the skin so if these are peeled during culinary preparation the polyphenol content will be reduced. Potatoes contain up to 190mg of an antioxidant called chlorogenic acid per kilo yet most of it is located primarily in their skin, makes a great case for eating potato wedges 🙂
Cooking also has an impact, one study observed onions and tomatoes lost 75-80% of their quercetin after boiling, 65% after cooking in a microwave oven and 30% after frying. Steaming vegetables leaves the highest levels of antioxidants.
The Fantastic Five
1) Cocoa
Throughout Aztec history cocoa has been renowned for its medicinal properties. Polyphenols in cocoa occur in higher concentrations than many other foods including the nutrition powerhouse that is broccoli! The catechins and procyanidins in cocoa lower your risk of cancer and heart disease, plus the polyphenols in cocoa improve the regulation of nitric oxide which plays a role in vasodialation helping to lower blood pressure. Studies have also observed supplementing with extra chocolate can help improve insulin sensitivity, decrease platelet aggregation and lower markers of inflammation.
For a high polyphenol content choose a dark chocolate with at least 60 percent cocoa solids but preferably more towards 70-85%. To increase the benefits add extra polyphenols including currants, dates, raspberries, blueberries or cherries as together they offer a synergistic effect. Limiting consumption to a 25-30g serving of dark chocolate or a single cup of cocoa daily provides the health benefits with minimal impact on your waistline.
2) Tea
Tea is one of the most researched of all the polyphenol foods and studies have discovered that tea leaves have a prebiotic effect in the gut supporting the growth of beneficial bacteria. All tea contain polyphenols; oolong and black teas undergo a little more processing so tend to have lower levels compared to green or white leaf tea. Tea polyphenols break down at high temperatures, so freshly brewed tea has higher amounts of polyphenols than ice tea or bottled tea drinks. Most research has focused predominantly on green tea and an active compound known as epigallocatechin gallate (EGCG) that has been shown to support weight loss, lower blood pressure, lower inflammation and exert an antimutagenic (anti-cancer) effect.
3) Apples
Population studies have linked the consumption of apples to a lower risk of certain cancers, cardiovascular disease, asthma and diabetes. Studies have observed the anti-inflammatory qualities of apple polyphenols in particular have an ability to protect the colon cells against free-radical damage and prevent bone loss in menopausal women. Sourcing local, chemical free is best and smaller apples which will have less sugar.
4) Wine
Well we knew you’d all be excited about this one! Remember the devil is in the dose and more than two small servings of alcohol will increase belly fat and have an estrogenic effect so go ahead if muffin tops and moobs are your thing.
Resveratrol is one of the most widely studied polyphenols in wine, found in the skin of red grapes (and peanuts!) Red wines will naturally contain more polyphenols than white or rose wines and Malbec grapes in particular have very thick skins so contain a little more resveratrol than other grapes. Pinot Noir, Syrah, Cabernet Sauvignon and Merlot are some of the highest polyphenol wines and the grapes grown in cooler climates tend to have higher resveratrol levels thus French wines are preferred over Californian. French wines are also aged more traditionally prolonging the contact with the skin and seeds, wines from the Languedoc-Roussillon and Côtes du Rhône regions are also renowned for having some of the highest levels of another polyphenol known as procyanidins. Wines from southern Italy, Sicily and Sardinia are also high in procyanidins.
The issue with wine nowadays is that mass production has resulted in an increased use of pesticides, fungicides and preservatives. Many supermarket and commercial wines are more just a cup of chemicals than anything else and these add to the hangover symptoms by placing extra burden on the liver. Ideally look for biodynamic (or ‘natural), organic wines with minimal sulphites added. You can buy a wide selection online, we buy from Vintage Roots.
5) Coffee
Matt is of course very happy about this! Research has indicated that coffee provides a whacking dose of polyphenols with over 1000 phytochemicals and the levels are similar in both caffeinated and decaffeinated coffee. An impressive number of studies have shown a strong association between consumption of coffee and a significantly reduced risk of diabetes, cardiovascular disease, cancer, Alzheimer’s disease and its also believed to improve intracellular signaling.
One cup of coffee a day (caffeinated or decaffeinated) can decrease the risk of developing diabetes by 13%, amazingly 12 cups a day reduces the risk by a whopping 67%, however, we do NOT recommend this (remember the devil is in the dose!) Most people can’t tolerate much more than 300 mg of caffeine per day, higher amounts may increase blood pressure, anxiety, insomnia and osteoporosis. Caffeine is not recommended for anyone with increased exposure to stress (er all of us?) and compromised adrenal function.
Remember not all coffee is equal. Opting for organic will have a higher polyphenol content. Also the roasting destroys some of the polyphenols, the most important being chlorogenic acid, new processing methods are being developed where the beans are soaked prior to roasting then deposited back into the same polyphenol rich liquid to return the beans to their original antioxidant content. Life Extension are one of the first companies to offer this ‘polyphenol retaining processed’ coffee and as super a this sounds we’re happy just sticking with our daily cup of Grumpy Mule or Monsoon Estates and an extra square of dark chocolate to bridge the gap 🙂
A Polyphenol Rich Day
That’s the best bit! A day of polyphenols is looking pretty cool if you ask us…
