Polyphenols and L-Carnitine Show Potential for Functional Foods

Two nutraceutical compounds are showing considerable promise for functional foods: polyphenols, found in tea, grapes, and olives and L-carnitine, associated with lean meats.

By Mark Anthony, Ph.D.

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One representative of functional food compounds generating renewed interest among developers and manufacturers of wellness foods is a group called polyphenols. The protective compounds, which guard plants against ultraviolet radiation and attack by various pathogens, are proving important in protecting people too.

A phenol is a molecule with some of its carbons arranged in a hexagonal ring. A multiple ring structure makes polyphenols efficient at trapping and scavenging free radicals, those corrupted compounds of oxygen implicated in cardiovascular disease and cancer. Our bodies generate free radicals in the process of converting foodl to energy, and during disease processes, we gladly take advantage of this ability.

Polyphenols are widely distributed in fruits, especially berries, grapes, cherries and other deep red and purple fruits. In fact, polyphenols were used as coloring agents before their potential health properties were investigated. There are thousands of identified polyphenols in plants and hundreds in the plants that we are likely to eat. The basic types of polyphenols are distinguished by the number of rings and how the rings are bound together. They include phenolic acids (cinnamic acids, benzoic acids), flavonoids (of which there are over 6,000 known), stilbenes, and lignans.

It is common for the average person to obtain about 0.5 to 2 g combined of these substances on a daily basis, depending up dietary choices. If you stroll through any well-stocked market or produce section, you'll practically trip over sources of polyphenols. Eggplant, onions, parsley, red cabbage, and kale are rich in flavonoids.

Teas, especially green and whites teas are rich sources of flavonols, a specific subgroup of flavonoids, which include molecules called catechins. Chocolate, apples and red wine contain flavonols known as proanthocyanidins.

Dr. Roberto Crea discovered that olive water — a waste product from olive oil production — is the richest known source of the potent antioxidant hydroxytyrosol. Courtesy of CreAgri, Inc.

The benefits of flavonoids and other polyphenols may extend to their ability to influence cell signaling pathways. The popularity of soybeans has soared in part due to their content of isoflavones, which have such structural similarity to estrogens they can bind to estrogen receptors and are termed "phytoestrogens."

Resveratrol is a fat-soluble stilbene found in grape skin extract, and is best known from the "French Paradox," the reduced rate of cardiovascular disease among those who consume red wine. In addition to its powerful antioxidant activity, resveratrol may reduce the risk of cardiovascular disease by inhibiting inflammation, platelet aggregation and proliferation of smooth muscle cells. There is some evidence that it also may prevent cancer cell proliferation.

Different polyphenols have different levels of bioavailability. Those most abundant in plants are not always the most available to human digestion and absorption. The simple way to enrich our diet with a variety of polyphenols is to eat a wide selection of colorful fruits and vegetables, beans and whole grains; drink some tea; and enjoy a glass of red wine with a little chocolate.

There are other avenues for getting enough of these helpful compounds. Dr. Qi Jia, chief scientific officer at Washington-based Unigen Pharmaceuticals Inc., screened over 1,200 medicinal plants to arrive at the polyphenol combination for Univestin, a natural joint health product.

And in Hayward, Calif., CreAgri Inc., a company producing neutraceuticals for functional foods, company founder Dr. Roberto Crea discovered that olive water — a waste product from olive oil production — is the richest known source of hydroxytyrosol, a potent antioxidant. CreAgri is marketing the product as Hidrox.

Tea is perhaps the best-known source of polyphenols. All tea comes from the leaves of a plant species Camellia sinensis.Taiyo International Inc., a pioneer in the science of green tea extracts, produces a line of polyphenolic catechins; epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate for their product Sunphenon, used to add antioxidants to beverages without adding tea flavor.

Dr. Jia believes more of this type of research is coming, along with the possibility of dietary recommendations for various polyphenols.

L-carnitine

In the category of chemicals we'd like our body to make more of at times is a compound called L-carnitine, from carnus, the Latin word for meat. This unique molecule performs a critical task in energy production. It binds and transports long-chain fatty acids in our cells into the mitochondria, the cells' fuel-to-energy-conversion furnace.

We find the highest concentration of L-carnitine in cells that use an abundance of fat for energy, such as skeletal and cardiac muscle. L-carnitine is assembled in the liver and kidneys from the essential amino acids lysine and methionine, a process that requires a good supply of vitamins C, B6, and niacin. It's then transported to other tissues.

We obtain some L-carnitine from red meats, such as lamb and beef, as well as from fish, poultry, dairy products and some vegetable sources such as tempeh, avocadoes, apples and tomatoes. Whole wheat bread is another source. We tend to be good at conservation, reclaiming about 95% of the L-carnitine that passes through the kidneys.

Though we make our own L-carnitine and obtain more from our diet, it has been described as a "conditionally essential nutrient," which means for certain populations it could be considered a dietary essential.


Mother's milk is rich in L-carnitine, but soybean-based formula contains almost none. Cow's milk loses some L-carnitine during processing. That's why supplementation of infant formulas with L-carnitine to match that of breast milk has been the routine for over 15 years.

L-carnitine synthesis decreases with age, and its status is placed at risk by a variety of diseases, such as kidney disease. With diminished L-carnitine, muscles can become over fatigued and movement impaired. Supplementation with L-carnitine can aid muscle function and increase exercise capacity for certain patients.

Peripheral arterial disease (PAD) is characterized by clotting of blood vessels in the legs which limits the ability of patients to exercise and move freely. Therapy with L-carnitine has been shown to increase muscle function and free PAD patients to walk greater distances.

Various drugs can play havoc with L-carnitine levels by draining them from the body. Fats in the form of free fatty acids supply the heart with about two-thirds of its fuel, and since L-carnitine is crucial for transport of free fatty acids to heart muscle, a deficiency in L-carnitine can reduce the oxygen necessary for effective heart muscle function.

A heart attack results in damage to the heart muscle. Treatment with L-carnitine, in addition to appropriate medical therapy, has been found to reduce heart muscle damage and improve in heart function.

A number of studies indicate L-carnitine may speed recovery from a heart attack, increase HDL cholesterol transporters, reduce triglycerides and lower blood pressure in patients with hypertension.

The role of L-carnitine in converting fats to energy and clearing away the metabolic end products that cause fatigue makes it an attractive candidate for weight loss and increasing athletic performance. Many studies indicate exercise performance and maximum oxygen consumption are increased in non-professional athletes. Results on weight loss are far less dramatic, and it is the general consensus that in both cases, more studies need to be done.

Still, L-carnitine is making its way into a number of new products, but mostly bars and beverages geared toward enhanced athletic performance. L-carnitine is definitely a functional compound to watch as application in foods spreads beyond that narrow category.

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