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A "super" carrot, packed with bone-building calcium, could eventually be headed to your dinner plate.

It's all part of a plan to boost the nutritional content of a wide variety of fruits and vegetables through genetic engineering. Scientists hope the fortified veggies could aid in the prevention of certain diseases. For instance, the extra calcium in a genetically modified carrot might help guard against osteoporosis, a brittle-bone disease that puts people at risk of debilitating breaks and fractures.

This week, U.S. researchers announced they passed a significant milestone on the road to making genetically enhanced foods part of our regular diet. They showed that people get substantially more calcium from the genetically altered plants, compared with garden-variety carrots.

In earlier work, researchers at Texas A&M University in Houston modified carrots by adding an extra gene that enabled the root vegetables to extract additional calcium from the soil. As a result, the engineered plants contained significantly more calcium than regular carrots. But it was not known if people could actually absorb the extra calcium from the enriched veggies.

So, the team at A&M University, along with researchers at Baylor College of Medicine in Houston, recruited 15 men and 15 women for a study. The results revealed that the volunteers absorbed 41 per cent more calcium from the gene-enhanced carrots than from common carrots.

The researchers are already developing other calcium-enriched foods, including potatoes and tomatoes, noted Jay Morris, lead author of the study published in the Proceedings of the National Academy of Sciences.

Still, a lot more research needs to be done before these super veggies are shipped to your local supermarket.

"The carrots were grown in controlled greenhouse conditions in a laboratory-type setting," said Kendal Hirschi, who was part of the research team. They must now be test-grown in real field conditions. "The risk is to move too quickly and claim these carrots are a cure-all - we simply have made some important first steps," Dr. Hirschi said.

The scientific community must also address safety and environmental concerns, particularly the possibility that a genetically modified vegetable might cross-breed with regular plants. Dr. Morris said carrots pose a low risk because they are biennial plants, producing seeds only once every two years. "That means all the carrots that are grown in a field for food production would be harvested ... before they have a chance to flower," he said.

One of the biggest challenges could be consumer resistance to what have been disparagingly dubbed "Frankenfoods." Even so, Dr. Morris envisions a day when genetically modified produce is sold alongside regular and organically grown fruits and vegetables. "I can see them just being another choice" for consumers, he said.

DEHYDRATED SENIORS

The elderly are at risk of severe dehydration because their aging brains no longer tell them how much they should be drinking, according to Australian researchers.

For the study, the team recruited 12 older men (aged 64 to 74) and 12 younger men (aged 21 to 30). Both groups were given an intravenous drip of salty water to make them thirsty. They were then allowed to drink as much as they wanted.

"Although all the participants had the same level of thirst, the older people only drank half as much as the younger subjects," said researcher Michael Farrell at the Howard Florey Institute in Melbourne.

As part of the study, participants' brains were also scanned by a PET imaging machine. The results revealed that a part of the brain involved in the regulation of thirst - called the midcingulate cortex - was "turned off" much sooner in the older volunteers.

The researchers suspect that many seniors could be afflicted by a "malfunctioning" thirst mechanism. And that could make them extremely vulnerable during periods of excessive heat or strenuous physical activity. Dehydration can cause headaches, lethargy and, in extreme conditions, even death.

During a brutal heat wave that overwhelmed Europe in the summer of 2003, about 52,000 died from dehydration and related causes - and many of them were older people.

"Scheduled drinking may be a strategy to reduce the risks of dehydration in older people although care should be exercised to prevent excessive water intake," they conclude in their study published in the Proceedings of the National Academy of Sciences.

ASPIRIN AND THE HEART

Acetylsalicylic acid, commonly known by its brand name Aspirin, has been used for years to treat cardiovascular disease. The medicine acts as a blood thinner - inhibiting the ability of blood platelets to form clots that can lead to heart attacks and strokes.

But a study by Canadian researchers confirms that many patients are "Aspirin resistant." In other words, they don't gain the same level of benefit from Aspirin as other people do.

The researchers reviewed 20 studies, involving 2,930 patients, and concluded that 28 per cent of them were Aspirin resistant. Furthermore, these same patients were resistant to other blood-thinning medications such as Clopidogrel and Tirofiban, according to the study led by Michael Buchanan at McMaster University in Hamilton.

"Being resistant to Aspirin makes patients four times more likely to suffer a heart attack [or] stroke or even die from a pre-existing heart condition," compared to other patients on the same medications, the researcher say in a statement released with their study published in the British Medical Journal.

"It is unclear whether these patients simply receive too low an Aspirin dose, are not compliant, have differing abilities to absorb Aspirin or have an underlying genetic disposition that renders Aspirin ineffective."

Despite their findings, they urge doctors to keep prescribing ASA to their patients. The therapy still provides at least some benefit. And they called for a study of alternative treatments that might be more effective for these patients.