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pco, quercetin, cartilage healing, tendon healing, ligament Healing

Can PCO and Quercetin Quicken Cartilage, Tendon, and Ligament Healing?

There’s been a lot about them in the news lately – about their potential to prevent cell damage and possibly decrease the risk of heart disease and even cancer. Bioflavonoids are unique, naturally occurring chemicals which are found in nearly all plants. The ubiquitous compounds are responsible for the bright colours of many fruits and vegetables (as well as autumn foliage), and now some scientists are contending that bioflavonoids may do more than just keep coronary arteries open: they might also help control sports injuries.

How could plant pigments limit damage to human tissues? Before answering this key question, let’s examine bioflavonoids in a little more detail. The omnipresent chemicals, which function as antioxidants in living organisms, were discovered 65 years ago by a Hungarian biochemist named Albert Szent-Gyorgyi, who went on to win a Nobel Prize for his investigations into bioflavonoids and vitamin C. Since Szent-Gyorgyi’s discovery, about 4000 bioflavonoid compounds have been detected in the natural world, including the relatively well-known flavones, flavonols, and isoflavones (anyone who hasn’t heard of these must be either a true, died-in-the-wool fish-and-chips person or else an old-school nutritional thinker who still classifies foods according to their protein, carbohydrate, and fat content, rather than their antioxidant status).

Preventing heart disease

One particular type of bioflavonoid, the proanthocyanidins (conveniently referred to as PCOs), has been closely linked with a number of health benefits, including the prevention of heart disease. The general-public’s interest in PCOs as potential cardiovascular-system protectors was first aroused in a scientific paper published in the Lancet in 1979. In this groundbreaking article, it was noted that French citizens, despite their love of foods rich in saturated fat (cheese, butter, goose liver, etc.), had a lower frequency of atherosclerosis than individuals with similar eating habits who lived in other countries.

The factor which produced this ‘French paradox’ was hypothesised to be the consumption – by the French – of rather voluminous quantities of wine. Wine, as it turns out, is one of the best sources of PCO (a 3.5-ounce glass of red wine can provide a rather hefty 150 mg of PCO), and PCO was presumed to protect against inflammatory degradation of the inner linings of coronary arteries. Subsequent research indeed found a nice (negative) correlation between the extent of flavonoid intake and heart troubles.

What it means to athletes

But what does all of this have to do with your sore Achilles tendon or those hurting ligaments in the lower part of your back? Bear in mind that your connective tissues cry out in pain when they become inflamed (in response to your overly intense or overly prolonged training or competition). Inflammation is a natural process; in fact, it is the basic means by which tissue healing is initiated and infection is limited within the human body. However, prolonged inflammation – the kind caused by aggressive training – can cause breakdowns in your tendons, ligaments, and/or bones. Part of this breakdown process is caused by the presence of ‘free radicals’ at sites of inflammation; these free radicals are not escaped political activists from the 1960s but are volatile chemicals which can in effect oxidise cell structures and create biochemical mayhem in inflamed regions of the body. These inflamed regions might be in the inner recesses of your heart, but they could also be in the plantar fasciae of your feet or in your tight, throbbing hamstrings.

How PCOs and quercetin work

PCOs enter the picture because they are ‘free-radical scavengers’ and overall antioxidants. They also inhibit the activity of enzymes which can break down key protein structures within tendons, ligaments, and cartilage during the inflammation process. In addition, they facilitate an enzyme called proline hydroxylase, which is absolutely essential for the synthesis of collagen. Collagen is the key structural protein in tendons, ligaments, some types of cartilage, and bone. PCOs have also been shown to have the ability to stabilise and increase the cross-linkage of collagen fibrils within connective tissues, an effect which should upgrade tendon and ligament strength.

Quercetin, another bioflavonoid, also seems to have pronounced anti-inflammatory properties. In one study, quercetin was able to reduce the production of free radicals by 33% and the release of protein-degrading enzymes by 52%. Other research suggested that quercetin tends to dampen the release of histamine, the chemical which helps produce the airway-tightening effect associated with exercise-induced asthma.

The scientific evidence

This all sounds very nice, but is there any hard evidence that PCO and quercetin might quiet down – or even help prevent – the connective-tissue inflammation in athletes which is associated with hard training? So far, the research is quite preliminary and not particularly focused on the athletic world, but the results in general are positive. For example, investigations carried out with rabbits found that PCOs were actually able to bind with elastic fibres in the rabbits’ ligaments and then prevent destruction of the ligaments by the potent enzyme, elastase.

One PCO which is being extensively researched is a compound called pycnogenol, which is a standardised extract from the bark of the French maritime pine. The utilisation of pine bark to relieve skin disorders is an ancient remedy, and those ancients weren’t just fooling around: there is now decent evidence to suggest that the pycnogenol in pine bark can reduce skin inflammations. For example, in one recent study, the effects of French-maritime-pine-bark extract on special human skin cells called keratinocytes was scrutinised. The pine-bark extract was shown to downregulate both ‘calgranulin A’ and ‘calgranulin B’ genes, both of which are know to be upregulated in inflammatory conditions such as psoriasis and various dermatoses; in other words, bark extract displayed an anti-inflammatory effect.

The German connection

Research on pycnogenol is currently taking off in Europe, especially in Germany, a country which carefully regulates its herbal supplements. In a recent review article, P. Rohdewald of the Institute of Pharmaceutical Chemistry at Westfälische Wilhelms University in Munster, Germany (communicate with him at’) surveyed pycnogenol studies which have appeared in peer-reviewed scientific journals, as well as those which have been presented at international scientific conferences. As Rohdewald pointed out, pycnogenol has very low acute and chronic toxicity with mild unwanted side effects occurring in a small percentage of individuals following oral intake of the substance. So far, clinical studies indicate that pycnogenol appears to be effective in the treatment of venous insuffiency (an inability of veins to return blood to the heart) and also retinal micro-haemorrhaging. It’s also clear that pycnogenol protects against oxidative stress by approximately doubling the intracellular synthesis of anti-oxidative enzymes and by acting as a free-radical scavenger. Further, pycnogenol seems to both protect and regenerate vitamins A and C, blocks UV-radiation-induced skin reddening, improves lung function in asthma patients, dilates small blood vessels leading to muscle tissues. There has even been a linkage between pycnogenol intake and improved cognitive function. No athlete’s tendons have been saved just yet, but it’s possible that pycnogenol may aid the recovery process during very strenuous training.

Back to grapes

Grapes (Vitis vinifera) and grape-seed extract are also high in PCO, so there has been considerable interest in how grape products might influence antioxidant activity in humans. In one recent study, ten healthy human volunteers took a daily dose of 110 mg of PCO (extracted from grapes) over a 30-day period. Fasting venous blood samples were taken before and at the end of the supplementation period. Interestingly enough, the levels of vitamin E in red-blood-cell membranes (and perhaps in muscle-cell membranes) increased by 56% over the one-month study, concentrations of degraded DNA in blood plasma dropped (degraded DNA is a sign of oxidant damage), and there was a shift to a higher level of polyunsaturated fatty acids in red-cell membranes.

The case against NSAIDS

All well and good, but why not just take nonsteroidal anti-inflammatory drugs (NSAIDS) for inflamed tendons, ligaments, and cartilaginous structures, as athletes have been doing in large numbers for the last two decades? NSAIDS do have a proven record of controlling pain and allowing athletes to continue along merrily with their training. The trouble is that NSAIDS also have a track record of side effects; up to 25% of individuals taking NSAIDS develop peptic ulcers, and a rather astounding 5% incur renal troubles. There is also disturbing evidence that NSAIDS may interfere with the metabolism of articular cartilage and the repair of bone.

So, PCO and quercetin are worth a look, especially since they appear to be completely safe when taken in reasonable quantities. Daily doses of PCO as high as 132 mg per pound (equivalent to almost 20 grams per day for a 150-pound person) have been found to be safe in animals. PCO (as pycnogenol, the pine-bark extract, or Vitis vinifera, the name often given to grape-seed extract) are commercially available as supplements, but you may reasonably choose to ingest them in real foods. The foods which are highest in quercetin include parsley, sage, onions, kale, red wine, broccoli, French beans, and apples; comestibles rich in PCO are cabbage, rhubarb, blueberries, currants, cranberries, grapes, raspberries (especially the black variety), strawberries, and of course red wine, two glasses of which will provide 300 mg of PCO. Note, however, that fresh foods have much higher concentrations of flavonoids than processed products – about double the levels, according to some studies.

The bottom line? The nutritional aspects of injury control for athletes remain poorly studied, but it is reasonable for athletes to increase their consumption of those fruits and vegetables which are high in flavonoids such as PCO and quercetin. These foods promote good health (which leads to more-consistent training and thus better performances), and there is also a chance that such food intake may be part of an effective strategy for controlling some types of oxidative damage which can result from very strenuous training.

Jim Bledsoe


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pco, quercetin, cartilage healing, tendon healing, ligament Healing