|GRAPHIC SLIDE: James Mills, M.D., M.S.
Dr. Mills on camera.
|Dr. James Mills: So the story about neural tube defects and folic acid is a very interesting one. Most people don't know what a neural tube defect is. So let me start out by explaining that. Very early in pregnancy, the embryo starts to make the central nervous system by, literally, taking a part of the embryo and rolling it around and forming a tube. That tube eventually forms the brain at one end and the spinal cord at the other end. And it's extremely important that the tube roll around and close. |
If it doesn't, then you get a major birth defect. And if it happens at the end where the brain is, you get a thing called anencephaly, where most of the brain never forms and most of the skull never forms. This is uniformly fatal. You never see a child with this.
If it happens at the other end, where the spine is being made, then you have an opening, and that's called spina bifida, and most people have seen or are aware of the problem of spina bifida. That also is a very, very serious birth defect, because there is paralysis below the level where the spinal cord is affected, so many of these children have difficulty with walking. Some of them have difficulty with other functions higher up. Bladder and bowel control are a big problem for these children. So it's a very, very serious and very costly birth defect.
Naturally, there was a tremendous interest among people in birth defects research to try to find out what caused it and how it could be prevented.
Many years ago, epidemiologists and clinicians noticed in the U.K. that the poorest people had the highest rates of having neural tube defects—much, much higher if you were in the lower socioeconomic strata. And a clever pediatrician, Dick Smithells, said, "I wonder if it's due to diet."
And he was able to take 900 pregnant women and measure vitamin levels during the pregnancy. At the end of the pregnancy, six of them did end up having babies with neural tube defects. He compared the vitamin levels and he said," You know, the vitamin levels are much lower for folate and for vitamin C." And so this got a whole group of people started doing trials where they gave women folic acid, which is the synthetic form of folate, before they became pregnant, to see if they could prevent the neural tube defects. And eventually they showed the folic acid did prevent about half of all the neural tube defects.
Now, from a public health perspective, there's one very important thing, and that is, as I said, this was a very early event in pregnancy. By the end of the 28th day after conception, this is done.
Dr. Mills on camera.
|Dr. Mills: So, from a public health perspective, the message had to be, "You need to take folic acid before you get pregnant, because in pregnancy, it's not going to do you any good." So a whole kind of a public health strategy had to be developed. |