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Bungee jumpers beware.

A 24-year-old California woman suffered permanent eye damage after taking a plunge while tied to a bungee cord, says a report in The New England Journal of Medicine.

A pool of blood, or a blood blister, formed at the back of her left eye as a result of the abrupt jerking stop. "The lady basically developed a loss of central vision ... in the eye due to the blood blocking light from reaching the retina," said Dr. Atul Jain, who treated her.

Even with surgery, her sight was not fully restored. "The vision was 20/20 before the jump. Now it's 20/25," said Dr. Jain of Stanford University.

He recently examined another patient who suffered a similar injury. "I don't think it is common [among bungee jumpers], but it is definitely scary when it does occur," Dr. Jain said in an e-mail.

"Certainly we can't recommend not to bungee jump due to a couple of profound cases of vision loss ... but it is worth noting this is a potential complication of this extreme sport."

DIABETES MEDS EXAMINED

Newer is not necessarily better when it comes to diabetes medications.

In fact, "the newer meds are no safer or no more effective than the older ones," says Shari Bolen, a researcher at Johns Hopkins University in Baltimore.

Dr. Bolen led a study that analyzed the safety and effectiveness of 10 different oral medications used to control the level of glucose in the blood.

People who suffer from type 2 diabetes are usually advised to make dietary and lifestyle changes in order to keep their blood-glucose levels in a safe range. But, eventually, most of them require one or more medications.

When they do need such a drug, their first choice should be a relatively old medication known as metformin, the research team concluded. "We found that metformin was similar to, or better than, other currently available oral agents," according to the findings published in Annals of Internal Medicine.

Better still, metformin, available as a generic drug, is substantially cheaper than the newer varieties.

Dr. Bolen noted that all medications - including metformin - have a range of side effects and patients respond differently to them. Metformin, for instance, can cause gastrointestinal upset. "While metformin was clearly better in subjects that can tolerate it," it is not for everyone, she added.

VITAMIN C: NO COLD CURE-ALL

If you are popping vitamin C tablets daily in hopes of avoiding the common cold, you are wasting your money.

A scientific review of 30 studies involving more than 11,000 volunteers found that the popular supplement offers little protection against coughs, sniffles and sneezes.

At best, vitamin C may shorten the illness - but not by much. It trimmed the duration of colds by 8 per cent for adults and 13 per cent for children, according to the findings published in the Cochrane Library, a non-profit publication that systematically reviews other medical literature.

However, there is one group that seems to profit from a daily dose - people who are exposed to short periods of extreme physical stress such as marathon runners. Vitamin C reduced this group's risks of a cold by 50 per cent, noted one of the authors of the report, Harri Hemila of the University of Helsinki.

Why should this group see a benefit, but not others?

Dr. Hemila explained that short bursts of extreme exercise produce lots of free radicals, highly unstable atoms that may put the body at risk for infections. Vitamin C, an antioxidant, apparently neutralizes these free radicals.

Regular exercise, on the other hand, doesn't produce the same level of unchecked free radicals.

So, unless you happen to be a marathon runner, the gains of supplementation are so marginal that "it doesn't make sense to take vitamin C 365 days a year to lessen the chance of catching a cold," Dr. Hemila said.

ptaylor@globeandmail.com