If you want to avoid an early menopause – and stay fertile longer – eat more whole grains, soy and tofu. That's the takeaway from a new study from epidemiologists at the University of Massachusetts Amherst and Harvard T.H Chan School of Public Health. The vegetable proteins found in enriched pasta, dark bread and cold cereal were especially effective.

Early menopause is defined here as the cessation of ovarian function before age 45. It affects about 10 percent of women and is associated with higher risk of osteoporosis, cardiovascular disease and early cognitive decline.

The researchers used the dataset from the the Nurses’ Health Study II; these surveys are among the largest prospective investigations into the risk factors for major chronic diseases in women. NHS2 is an ongoing prospective study of 116,000 women aged 25-42 when they entered it in 1989.

The data indicated that women consuming approximately 6.5 percent of their daily calories as vegetable protein had a 16 percent lower risk of early menopause compared to women whose intake was approximately 4 percent of calories. In a 2,000 calorie per day diet, this would parse out as three to four servings of such foods as enriched pasta, breakfast cereal, tofu and nuts – about 32.5 grams a day. The scientists adjusted their math for body mass index, age, smoking and other potentially water-muddying factors.

The data tracked the lifestyles of nurses over two decades, and re-assessed the health of participants every two years. Diet was assessed five times over the 20-year study, allowing the researchers to capture within-person variation in changes in food and nutrient intake over times. Over the course of the study, 2,041 women experienced early menopause.

The authors noted that although “relatively few women in our study consumed very high levels of vegetable protein and our power for analyses of more extreme intake levels was limited, women consuming 9 or more percent of their calories from vegetable protein had a hazard ratio of 0.41” compared to those eating less than 4 percent.

The research was published in the American Journal of Epidemiology.