March 4, 2008 -- Kate Moss wants a baby — so badly, in fact, that she has switched her diet to that used by actress Gwyneth Paltrow to aid her fertility, according to British media reports.
But can a change in diet actually help increase the odds of getting pregnant? Nutrition and reproductive health experts say yes — but add that a healthy diet for fertility may have more to do with common sense than fad regimens.
Dr. Jorge Chavarro, research fellow in the department of nutrition at the Harvard School of Public Health in Boston, is also co-author of The Fertility Diet, a book published last year that reveals some of the links between certain foods and a woman's ability to conceive.
"We know that there are multiple aspects of diet that have been associated with a decreased chance of experiencing a certain decrease in function when it comes to fertility," he says.
Reproduction and nutrition experts agree that a healthy diet can go a long way toward improving fertility in a number of ways.
"Poor nutrition has been associated with fertility issues and ovulation problems," notes fertility specialist Dr. Celia Dominguez, assistant professor of gynecology and obstetrics at Emory University in Atlanta. "Diet plays a critical role, and by improving her diet a woman can also improve her chances of making an egg."
But Chavarro adds that while his research, gleaned from the now-famous Harvard Nurses' Study, suggests certain dietary changes that women can make, most of what he and his colleagues have found is that a fertility-friendly diet has few surprises.
"What we have found does not necessarily point toward any specific miracle food other than an overall, generally good and healthy diet," he says.
Of Fads and Fertility
"You can certainly identify a few nutrients that have a relation to reproductive status," says Dr. David Katz, associate professor of public health and director of the Prevention Research Center at Yale University in New Haven, Conn. But he adds that the true picture of diet and fertility is often complicated by the new diets and fertility claims that hit the scene on a regular basis.
And because Paltrow had reportedly adhered to what is known as a macrobiotic diet in an effort to help her pregnancy chances, this could be the fad diet du jour upon which many women who want to conceive hang their hopes.
"I'd have some concerns," Katz says. "People interpret a 'macrobiotic diet' differently."
He says most worrying about the macrobiotic diet is how it becomes progressively more restrictive. By the end of the diet, strict followers are consuming only unprocessed rice and water — a poor formula for fertility.
"The basic attributes of a macrobiotic diet are fine — plant-based, natural and organic," Katz says. "And yes, this type of diet has the potential to enhance fertility, as it helps in insulin regulation and increasing levels of certain hormones. But if it were a very strict interpretation, I would caution against that."
Dominguez says different fad diets aimed at enhancing fertility may lead to more stress than they are worth.
"A lot of these diets have not been tested, and they can be very confusing to consumers," she says. "In general, the guidelines are very simple. You want appropriate eating, and no missing of meals. You want to avoid trans fats. You want to focus more on vegetable proteins than animal proteins. You want to get your folic acid, and have very moderate coffee and caffeine intake. And if you are overweight, if you can decrease your weight by 5 to 10 percent it could be helpful."
Full-fat dairy products — such as whole milk and ice cream — also appear to encourage fertility more than their low- or non-fat counterparts.
He says other nutrients — most notably folate and omega-3 fatty acids — have an impact on the preparation of the uterus lining for the proper implantation of a fertilized egg and normal development.
And nutrients known as phytoestrogens may also affect fertility, Katz says. These nutrients, present in soy-based products and some other plants, may raise the levels of the sex hormone estrogen in women's bodies, making them more likely to be able to conceive.
One interesting piece of evidence that appears to point at this possibility is research on a population in Nigeria that has the world's highest recorded rate of twin births. It turns out that a staple of these people's diet is a type of yam that has been shown to be one of the most concentrated sources of phytoestrogens in any food.
But barring these special yams, Katz says, "The general advice is that if you want to make any changes to your diet in the hopes of conceiving and having a baby, you should probably be looking for a healthy diet with lots of whole grains, fruits and vegetables, and high in folate and omega-3 fatty acids."
Diet Can't Cure All Fertility Ills
In some cases, it's not what a woman eats, but how much food she's eating on a regular basis, that could play the biggest role in fertility.
Body weight, Chavarro says, is "probably one of the first places couples who are facing problems with fertility should look."
But, in some cases no amount of diet and lifestyle changes will not solve the problem. In these cases, he says, a couple's best chances for having a biological child is assisted reproduction.
These problems include scarring in the fallopian tubes, or structural problems within the uterus that would discourage the implantation of a fertilized egg.
And, of course, male fertility is also a big part of the equation.
"It does take two to tango," Katz says. "If a guy has a low sperm count or motility problems, there may not be much that a woman can do in terms of her diet to correct that."
But a focus on diet can't hurt. Model Moss, who is 34, has also supposedly made an effort to kick her coffee and nicotine habits — adjustments that can only help her chances at conceiving.