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Food for Thought

Janet Raloff
Food for Thought

Drink Those Antioxidants

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Mention antioxidants and most people will immediately think of vitamins–typically C and E–usually in the form of mega-dose capsules available at the local drug store. However, a new study finds that many common beverages also deliver a healthy antioxidant serving.

These beverages may give some protection against the ravages of oxidizing chemicals that we breathe in or that cells in our bodies produce as the cells go about their normal housekeeping functions.

Over the past few years, studies have demonstrated the damage that an overabundance of oxidizing chemicals can inflict. Some oxidizers contain oxygen, others dont. What these molecular fragments have in common is that they are missing an electron. Hungering for that subatomic particle, they exhibit a propensity for stealing an electron from any nearby molecule. The newly depleted molecule now feels the urge to steal an electron to again become whole, leaving its victim to find a replacement electron. So begins a potentially catastrophic chain reaction.

This process can damage cells–even kill them. Its one means by which smog ozone damages the lung. Oxidation is also a primary means by which the body kills invaders, such as viruses and bacteria, or removes aging or sick cells. However, the body unleashes antioxidants to stop the chain reaction after a brief period.

Unfortunately, with age our antioxidant-production systems begin to poop out. As their efficiency wanes, each new oxidant onslaught risks more and more collateral damage to healthy tissues. Indeed, oxidation plays a role in many degenerative diseases–including the development of artery clogging plaque.

Research has shown that oxidation of cholesterol-rich low-density liproteins (LDLs)–the so-called bad lipoproteins–contributes to their transformation into fatty plaque. So, scientists often test the potential benefits of dietary antioxidants by measuring their ability to protect LDLs from oxidation.

Thats what scientists at the renowned chocolatier Nestlé have just done. Previous studies by others–notably by Mars, Inc., maker of M&Ms–showed that dark chocolate triggers a number of beneficial changes that would appear to slow the ravages of atherosclerosis (see "Chocolate hearts" at http://www.sciencenews.org/20000318/bob2.asp). A host of other studies has demonstrated that tea contains potent antioxidant flavonoids and that the quantity regularly consumed in tea tends to correlate with heart health. Nestlé looked to see how its products stacked up against tea and coffee in this regard.

In the July Agricultural and Food Chemistry, Nestlés Myriam Richelle and her colleagues report finding that hot cocoa does offer some benefit–though not as much as coffee.

Forget the herbal teas

The scientists brewed a strong cup of coffee or tea, or they mixed cocoa powder into hot water to make hot chocolate. Then, they collected blood from healthy volunteers and filtered out the plasma containing LDL particles. In each run, a sample of these LDLs was incubated with a small quantity of the beverage. Then, a known oxidant was added to the mix.

Compared to LDLs treated with the oxidant alone, those mixed with a beverage experienced less oxidation. The protection afforded by each beverage was indicated by the time it took the LDLs to oxidize–the longer the lag time, the better the protection.

In this experimental setup, coffee protected the LDLs for 5.0 to 16.0 hours. By contrast, cocoa protected the lipoproteins for 3.5 to 7.5 hours, green tea for 3.0 to 5.5 hours, black tea for 1.0 to 4.5 hours, and herbal tea for 6 minutes to perhaps an hour. The range of times for each beverage reflects the varying strengths of the batches prepared. Because there is considerable variation between countries in the way each typically prepares a particular drink, these scientists formulated each beverage in various strengths–and observed a marked dose-dependence in their effects. The more concentrated the brew or cocoa, the better protection it afforded.

And what happens if you add milk?

Concerned that milk might bind to the antioxidant compounds in one or more of these beverages, Richelles group investigated whether adding dairy would compromise a drinks antioxidant potency. The scientists mixed in enough milk to equal 10 percent of the volume for the brews and a full 66 percent of the volume for cocoa. To their surprise, they found no change in any of the drinks LDL protection.

Prefer decaf? Thats okay. Caffeinefree coffee offered the same LDL protection in these test-tube studies that the joltin joe provided.

There is reason to believe the relative benefits seen in the test tubes will hold up in the body. Earlier this year, Japanese researchers showed that the quantity of oxidized LDL in an individuals blood correlated with the severity of a mans or womans heart disease (SN: 4/21/01, p. 245).

In that a little alcohol also seems to benefit the heart, I think Ill reach for a healthy dose of Irish coffee. In fact, lets make it an Irish mocha.


Myriam Richelle

Nestlé Research Center

Post Office Box 44

1000 Lausanne 26

Further Reading

Raloff, J. 2001. Blood markers of clogging arteries emerge. Science News 159(April 21): 245.

____. 2001. Pulling antioxidants starves cancers. Science News 159(April 21):248.

____. 2000. The power of caffeine and pale tea. Science News 157(April 15):251.

____. 2000. Panel ups RDAs for some antioxidants. Science News 157(April 15):244.

____. 2000. Chocolate hearts. Science News157(March 18):188. Available at [Go to].

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