Do tea, coffee drinkers have lower "superbug" risk?

A barista prepares a coffee drink in in Bogota, Colombia June 3, 2011.

Credit: Reuters/Fredy Builes

By Amy Norton

NEW YORK | Thu Jul 14, 2011 11:24am EDT

NEW YORK (Reuters Health) - People who regularly drink tea or coffee may be less likely to carry the antibiotic-resistant "superbug" MRSA in their nostrils, a new study suggests.

Researchers found that of more than 5,500 Americans in a government study, those who drank hot tea or coffee were about half as likely as non-drinkers to harbor MRSA bacteria in their nostrils.

Exactly what it all means, though, is unclear.

MRSA (pronounced "mersa") stands for methicillin-resistant Staphylococcus aureus, a type of bacteria that causes staph infections that are resistant to several common antibiotics. In hospital patients, MRSA can cause life-threatening pneumonia or blood infections. In the general public, it typically causes painful skin infections, but those can sometimes develop into serious invasive infections.

A small segment of the population -- about one percent -- carries MRSA in the nose or on the skin but does not get sick.

For the new study, reported in the Annals of Family Medicine, researchers looked at whether coffee or tea drinkers were any less likely than other people to harbor MRSA in the nose.

The idea for the study came from the fact that, in both the lab dish and in humans, topically applied or inhaled tea extracts have shown some anti-MRSA activity, explained lead researcher Dr. Eric M. Matheson, of the University of South Carolina, Charleston.

Less research has been done on coffee compounds, he told Reuters Health, but there is some evidence of antibacterial powers there as well.

Matheson's team found that, indeed, tea and coffee drinkers were less likely to carry MRSA.

Overall, 1.4 percent of the study group harbored the bacteria in their noses. But those odds were about 50 percent lower among people who said they drank hot tea or coffee, versus non-drinkers.

The big caveat, though, is that the link does not prove that tea or coffee, themselves, are the reason for the lower risk.

The study shows an association between the two, Matheson said, "but you never can conclude causation from an association."

"I can't tell you that this finding isn't just a coincidence," he said.

The researchers tried to account for several other factors -- like whether differences in age, income or self-rated health explained the difference between tea or coffee drinkers and non-drinkers. And the beverages were still linked to lower odds of being a MRSA carrier.

But, Matheson said, there could still be other explanations for the connection.

For now, he stopped short of recommending that people start drinking coffee or tea in the hopes of fending off MRSA.

"Based on one association study, that would probably be saying too much," Matheson said.

Another question is, even if coffee and tea drinkers do have a lower chance of carrying MRSA, are they any less likely to get sick? Matheson said there is still debate about whether MRSA carriers are at increased risk of developing an active infection.

It's estimated that in 2005, MRSA caused severe infections in 95,000 Americans, killing nearly 19,000.

The rate of hospital infections has gone down in recent years, according to the Centers for Disease Control and Prevention, but MRSA infections in the general population have been on the upswing since the 1990s and have shown no reversal yet.

To cut the risk of contracting the superbug, experts advise that people regularly wash their hands, keep skin wounds covered, and avoid sharing personal items like towels, washcloths and razors.

And those preventive steps are key, Matheson noted, whether you're a java lover or not.

SOURCE: bit.ly/qA66m7 Annals of Family Medicine, July/August 2011.

Vitamin C from food tied to lower cataract risk

1 of 2. Tomatoes are on display at an organic fruit and vegetable stall at a market in Montalivet, southwestern France, August 13, 2009.

Credit: Reuters/Regis Duvignau

By Amy Norton

NEW YORK | Thu Jul 14, 2011 2:41pm EDT

NEW YORK (Reuters Health) - Older adults who get very little vitamin C in their diets may have an increased risk of developing cataracts, a study in India finds.

Cataracts are a clouding of the eye's lens that commonly cause vision problems in older people. Some studies, but not all, have found that people with higher intakes of antioxidants, including vitamin C, may have a lower risk of developing the condition.

But those studies have been done in Western countries -- and not in lower-income countries like India, where people's vitamin C levels tend to be very low and rates of cataract are particularly high.

For the new study, researchers evaluated more than 5,600 Indian adults age 60 and up for cataracts. They also interviewed them about their diets and lifestyle habits, and measured their blood levels of vitamin C.

Overall, nearly 73 percent of the study participants were found to have cataracts. But that risk dipped as vitamin C blood levels and vitamin C intake rose.

In the roughly one-quarter of older adults with the highest vitamin C levels, the risk of cataract was 39 percent lower than in people with the lowest levels of the nutrient. That was with factors like income, smoking habits, high blood pressure and diabetes taken into account.

But vitamin C levels were generally very low. More than half of the study participants were deficient, and the bottom 30 percent of the group had vitamin C concentrations below the level of detection (2 micromoles per liter).

Anything below 11 micromoles per liter is considered a vitamin C deficiency.

Even in the group with the highest vitamin C levels, the typical amount was just 38 micromoles per liter. By comparison, in cataract studies in Europe and the U.S., the "high-C" groups have had levels of 70 micromoles or higher.

The findings, reported in the journal Ophthalmology, do not prove that adequate vitamin C protects against cataracts.

But it's biologically plausible, said senior researcher Astrid E. Fletcher, a professor at the London School of Hygiene & Tropical Medicine in the UK.

Vitamin C is an antioxidant, which means it helps protect body cells from damage caused by so-called oxidative stress.

"Laboratory and animal studies show vitamin C plays a very important part in defending the lens of the eye against oxidative stress," Fletcher explained in an email.

"The eye is particularly vulnerable to oxidative stress as the 'seeing' organ of the body," she added. "Light is essential for vision but light is also very damaging. The lens absorbs ultraviolet radiation, a major source of oxidative stress."

But that biological plausibility does not mean that older adults should load up on vitamin C supplements to ward off cataracts.

Fletcher said the current findings have relevance primarily for India, where people's vitamin C levels are generally low. They might also have implications for other lower-income countries, she added, but those studies have not been done yet.

In Western countries, studies have come to conflicting conclusions as to whether people with high vitamin C intakes have a lower cataract risk.

What's more, clinical trials that have tested high doses of vitamin C and other antioxidants for preventing cataracts have failed to show a benefit.

One reason, Fletcher noted, may be that well-nourished people in high-income countries already have fairly high vitamin C levels, and an extra dose from a pill has little benefit to offer. Vitamin C is water-soluble, and excess amounts are quickly excreted from the body.

Another possibility, according to Fletcher, is that taking a few nutrients in pill form simply does not mimic the effects of a good diet.

Foods high in vitamin C include citrus fruits like oranges and grapefruit, green and red peppers, kiwifruit, strawberries, broccoli and tomatoes. In the U.S., the official recommendation is for men to get 90 milligrams of vitamin C per day, while women should get 75 milligrams.

In this study, most older Indian adults were getting well below that.

If extra vitamin C was shown to lower cataract risk in India, the benefits could be substantial.

"India has the highest burden of blindness in the world," Fletcher said, "and the main cause is cataract."

SOURCE: bit.ly/pdR2l1 Ophthalmology, online June 27, 2011.

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