PhilRice’s Biotechnology head explains why Golden Rice poses no Vitamin A toxicity risk

AFTER lawmakers, farmers and consumers bombarded the golden rice project with criticisms during a roundtable discussion at the House of Representatives, a Philippine Rice Research Institute (PhilRice) official clarified the safety issues raised against the genetically modified rice variety.

In an interview with The Manila Times, Dr. Antonio Alfonso, PhilRice’s Crop Biotechnology Center director and golden rice project leader, says that contrary to reports, vitamin A toxicity is not a risk in the human consumption of golden rice.

Seen as a solution to vitamin A deficiency (VAD), golden rice is designed to produce in its grains the carotenoid beta-carotene, which when consumed is converted by the body to vitamin A. The rice plant does not normally produce beta-carotene in its grains, but in its leaves. But through genetic engineering, two carotenoid genes are added to the rice plant for it to produce beta-carotene in its grains.

Alfonso explains that the body only converts beta-carotene to vitamin A when it needs it, and excess beta-carotene is stored in fat and other tissues and or excreted.

“There is no evidence that conversion of beta-carotene to vitamin A contributes to vitamin A overdose or toxicity even when beta-carotene is ingested in large amounts,” adds Alfonso who is also a chief science research specialist at PhilRice.

Alfonso explains his position on the report about the dangers of golden rice that US-based senior scientist Dr. Michael Hansen presented before legislators during the roundtable.

Hansen reported that when beta-carotene is in the intestine, it generates the chemical compound retinal which can be reduced to retinol (vitamin A) or oxidized to retinoic acid, which is toxic and teratogenic or “able to disturb the growth and development of an embryo or fetus.”

But Alfonso says that “in 2009, scientific experts in the field of carotenoids (beta carotene is a type of carotenoid) reached a consensus finding that beta carotene is a safe source of vitamin A, including retinoids, retinol, and retinoic acid.”

He also stressed that the golden rice project follows internationally accepted guidelines for testing safety prior to human consumption. The tests include potential toxicity and allergic properties, nutrition, stability of the genes, and unanticipated effects. And the golden rice test results, he says, have all indicated that it is as safe as the rice varieties now being eaten.

PhilRice understands that there are reports questioning the nutritional efficacy of golden rice in addressing VAD. Alfonso says that many studies about golden rice 2—which produces much more beta carotene than the original golden rice and the variety being subjected to tests—have been conducted to determine the availability of beta carotene in the rice.

These nutritional studies, he says, are funded by the US National Institute of Health and have yielded encouraging results. They indicate that one cup of golden rice could meet 50 percent of an adult’s vitamin A needs.

As to the criticism that the field testing of golden rice may result in environmental risks such as the
possibility that it will cross-pollinate with commercial rice varieties, Alfonso says that it has been determined that any cross-pollination or out crossing of golden rice would not cause health or safety issues.

Field tests and other evaluations, he says, are part of national regulatory requirements, which are based on internationally established procedures, which local regulators use to determine the environmental impact of genetically modified crops. Field trials are important because these will show if golden rice is suited to local conditions and will produce data that the Department of Agriculture (DA) will use to assess the safety of golden rice.

“Field trials are conducted with approval from the Department of Science and Technology-Biosafety Committee and the Bureau of Plant Industry,” says Alfonso. “And we (PhilRice) follow the biosafety requirements of the regulations and as specified by the regulators.”

Currently, the International Rice Research Institute (IRRI) has conducted confined field test of golden rice in the popular rice variety IR-64 as well as in leading Philippine and Bangladeshi varieties from the end of 2010 to the beginning of 2011. PhilRice, on one hand, has done confined field test of golden rice in PSB Rc-82 and IR-64 varieties in the first quarter of 2011.

Data from the confined field tests, including agronomic and product performance, will be evaluated and analyzed when the trials are complete and then PhilRice will formally publish the results, according to Alfonso.

He also says that the trials are an important part of PhilRice’s breeding program. Through the tests, PhilRice checks if golden rice retains high yield, pest resistance, and excellent grain and eating qualities.

The field trials should be completed by 2013, and the application for the approval of golden rice with DA may be made in the same year. Further nutrition testing would take place after the approval to assess if golden rice adequately reduces VAD.

“Golden rice is undergoing rigorous safety evaluations as it is developed. It will be available to farmers and consumers only after it has been determined to be safe for humans, animals and the environment and authorized for propagation and consumption by regulatory authorities,” Alfonso stressed. “Therefore, golden rice, if and when released, will be safe for people to eat and safe for the environment.” –Claire Mercado, Writer-Researcher, Manila Times