BioEd Online

The humble cress has never been so wholesome. UK researchers have modified the plant so that it produces health-promoting chemicals that are more commonly found in eggs and fish.

The chemicals in question are polyunsaturated fatty acids (PUFAs) called omega-3 and omega-6. Both types of molecule help regulate blood pressure, modify the immune response and aid cell signalling. Omega-3 fatty acids are also thought to aid brain development, and help protect adults from heart disease and rheumatoid arthritis.

"It's important to get a healthy balance of the two," says Baoxiu Qi from Bristol University in Britain. His team created the new cress strain by adding three genes from algae and mushroom species that produce these PUFAs naturally. They report their results in Nature Biotechnology¹.

Although the lab-grown crop is unlikely ever to be eaten, it proves that plants can be genetically tweaked to produce these fatty acids. And it paves the way for future generations of healthier vegetables and other foods.

Plants like this could be consumed directly by humans, or enter the food chain after being fed to animals, says dietician Catherine Collins from St. George’s Hospital, London. "We're increasingly seeing a move towards functional foods with added health benefits."

The fats of life

Our bodies cannot make omega-3 or omega-6 fatty acids, so they have to be obtained from our diet. Poultry and eggs are good sources of omega-6; cereals and cold-water fish such as salmon, halibut and sardines yield omega-3.

But fish stocks are declining, prices are rising and many are worried that fish contain unhealthily high levels of toxins, such as polychlorinated biphenyls (PCBs) and dioxins.

So researchers are searching for other convenient foods that contain both types of PUFA. British supermarkets have recently begun marketing PUFA-rich chicken eggs, produced by poultry fed on cereal rich in omega-3. Qi and his team hope their method will provide palatable vegetarian options.

Wind of change

PUFA-rich plants could have another important benefit: they might make cows belch less. The fatty acids help block methane production in cow stomachs, and could help reduce greenhouse gas emissions if used in animal feed.

It is a serious issue, says Qi. As food ferments in the animal's stomach, hydrogen is produced, which reacts with carbon to produce methane. Although the exhaled gas accounts for less than 3% of total greenhouse gas emissions in fossil-fuel burning countries, such as Britain and the United States, it makes up nearly 40% of emissions in agricultural New Zealand.