GM carrots could cut osteoporosis risk

Altering a gene responsible for the transport of calcium across the plant cell membrane, researchers from Texas A&M University report that absorption of the mineral from the carrots can be increased by 41 per cent.

The research, assuming it can overcome the 'GM tag', could offer an alternative approach to boosting calcium intake among the population with the knock-on effect of potentially reducing the risk of osteoporosis.

Osteoporosis is currently second only to cardiovascular disease in terms of global healthcare burden, according to the World Health Organisation, affecting some 200 million people today but the number of sufferers is set to increase steadily with growing numbers of elderly living longer, and obesity adding extra strain on bones.

"To help compensate for [high levels of calcium deficiency in the US], one strategy is to increase the calcium content of the foods they do eat," wrote lead Jay Morris in the Proceedings of the National Academy of Sciences .

"Here, we have shown the ability to improve the bioavailable calcium content of a staple food; when applied to a wide variety of fruits and vegetables, this strategy could lead to more calcium consumption in the diet."

The researchers focused on the sCAX1 gene that controls the levels of a plant calcium transporter, and produced carrots with an altered form of the gene which improves calcium absorption.

They tested the carrot in both mice and in a small number of humans.

Morris and co-workers report that mice fed the carrots with the altered gene could get the same amount of calcium as those who ate twice the amount of normal carrots.

Importantly, in the study with 30 humans (average age 25, 15 women), it was found that consumption of the modified carrots produced a 41 per cent increase in calcium absorption than did those who ate the unmodified carrots.

"Slightly altering the gene (sCAX1) to make it a more active transporter allows for increased bioavailable calcium in the carrot- ," said lead researcher Dr. Kendal Hirschi.

"These carrots were grown in carefully monitored and controlled environments," he added.

"Much more research needs to be conducted before this would be available to consumers."

Beyond carrots "Although this work represents initial studies toward understanding the nutritional impact of transgenic foods, the technology may be eventually applied to various crops because it involves the over-expression of a gene found in all plants," wrote the researchers.

"Additionally, the approach in this work can serve as a paradigm for related similar hypotheses about the role of other plant alterations to the bioavailability of nutrients contained within the plant matrix," they concluded.

Commenting independently on the research, Professor Susan Fairweather-Tait of the University of East Anglia told the BBC that genetically engineering to boost the nutrient content of food was becoming an increasingly important.

"People are being told to eat more modestly to prevent weight gain, and many diets now no longer contain everything we need.

"There has been great resistance to genetic engineering, but gradually we are moving away from the spectre of 'Frankenstein food' and starting to appreciate the health benefits it may bring," she said.

Indeed, a number of genetically modified plants and crops are coming to light with enhanced nutritional content considered to offer human health benefits, including flavonoid-rich tomatoes, zeaxanthin in potato tubers, and the omega-3 fatty acid, eicosapentaeoic acid (EPA), to soybeans, brassica, and stearidonic acid (SDA) in canola crops.

However, no GM crops with potentially enhanced health benefits have been approved for human consumption in the EU.

Consumer acceptance, particularly in Europe and most notably in the UK, continues to be one of the biggest challenges for these crops.

Source: Proceedings of the National Academy of Sciences Published online ahead of print, PNAS Early Edition, doi: 10.1073/pnas.0709005105 "Nutritional impact of elevated calcium transport activity in carrots" Authors: Jay Morris, K.M. Hawthorne, T. Hotze, S.A. Abrams, K.D. Hirschi