The most comprehensive study to-date looking at diet and fertility is the Harvard Nurses' Health Study that followed over 18,000 women in a long-term research project looking at the effects of diet and other factors on the development of chronic disease. Chavarro and Willett looked at the fertility data from this study in The Fertility Diet (2008). During the study, each woman was trying to have a baby. Over eight years of follow-up, the study found that most did get pregnant. However, one in six women encountered some problems getting pregnant. The results were incredible – even to the researchers – who found a six-fold increase in fertility in people who ate a certain diet and maintained a certain lifestyle. Specifically, the study found that women who had the lowest risk of ovulation problem-related infertility (or the highest fertility) ate a plant-based, low GI, whole foods diet focusing more on vegetable protein and monounsaturated fats. Women with the highest fertility exercised more, took a multivitamin mineral supplement and ate at least one serving of high-fat dairy each day.