2 items on the Golden Hoax:
1. 'Nutrition science... suggests golden rice alone will not greatly diminish vitamin A deficiency and associated blindness' says head of nutrition and food studies department at New York University
2. Potrykus admits higher levels needed
Letter to the editor
New York Times Science Section
December 19, 2000
To the Editor:
Two articles ("Gene Altered Foods: A Case Against Panic" (Dec. 5) and "Golden Rice in a Grenade Proof Greenhouse" (Nov. 21) state that genetically engineered golden rice will help alleviate vitamin A deficiency, a common cause of blindness among children in developing countries.
Nutrition science, however, suggests that golden rice alone will not greatly diminish vitamin A deficiency and associated blindness.
Golden rice is engineered to contain three new genes that together cause rice to produce beta carotene. Beta carotene is a precursor of vitamin A; it must be split by an enzyme to be active. Beta carotene and vitamin A are fat-soluble, meaning that they require fat in the diet to be absorbed through the intestinal wall.
Conversion of beta carotene to vitamin A, and transport in the body to the tissues that use vitamin A, require diets adequate in fat and protein.
People whose diets lack these nutrients or who have intestinal diarrheal diseases - common in developing countries - cannot obtain vitamin A from golden rice.
Golden rice represents sophisticated genetic engineering. But it will not conquer the main causes of vitamin A deficiency - malnutrition and poor sanitation. Conquering these problems requires more challenging interventions than a single high-tech product.
DR. MARION NESTLE New York The writer heads the nutrition and food studies department at New York University.
[Love the bit about the secret strategy. Reminds me so much of the sort of answer an 8-year-old might come up with when quizzed about how he's going to get the robot he and his friends are busily planning to actually work. Toys for boys!]
AgBioView - http://www.agbioworld.org
Re: The Reality of Golden Rice?
This is an endless discussion and not too helpful. The basic message is right: we are tying to achieve a pro-vitamin concentration which has an effect on the basis of 300g of rice (not 30 as the writer is using). With our 1.6 microgram/gram we are at the lower level of what we want to achieve. The VAD values given tell only part of the story and are mostly rather luxurious. There is also no agreement on the conversion ratios, and we have no data yet on the bioavailability and the stability during storage. And it is very difficult to get reliable data, from which level on additional provitamin A within the diet has an effect in different stages of vitamin A-deficiency. We also do not have to provide the total amount required because nobody has zero provitamin A in the diet.
I prefer to: a) continue to work towards higher levels in endosperm (we have several independent approaches running); b) continue with a (still secret) strategy which may change the discussion immediately (data we will have in two month); and c) wait for real data from bioavailability studies with "Golden Rice".
We will never have the problem of overdosing, but we may arrive at a compromise which decides not for the maximum possible to not built a to high hurdle for acceptance (Golden Rice with the amount of provitamin A required to provide 100% of an US VDA, probably, would no longer look golden, but darker red than the reddest carrots, and such a rice not many people will like to eat.
With best regards, Ingo