"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."
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.