"This work on the role of nutrition in early life and breast cancer incidence suggests one of the very few potentially modifiable risk factors for premenopausal breast cancer," Faravid wrote.
The researchers looked at a group of 90,534 women who participated in the Nurses' Health Study II, a large long-running investigation of factors that influence women's health. In 1991, the women -- ages 27-44 at the time -- filled out questionnaires about their food intake, and did so every four years after that. They also completed a questionnaire in 1998 about their diet during high school.
The researchers analyzed the women's fiber intake while adjusting for a number of other factors, such as race, family history of breast cancer, body mass index, weight change over time, menstruation history, alcohol use and other dietary factors.
Researchers found that breast cancer risk was 12 percent to 19 percent lower among women who ate more dietary fiber in early adulthood, depending on how much more they ate. High intake of fiber during adolescence was also associated with 16 percent lower risk of overall breast cancer and 24 percent lower risk of breast cancer before menopause.
Among all the women, there was a strong inverse association between fiber intake and breast cancer incidence. For each additional 10 grams of fiber intake daily during early adulthood, breast cancer risk dropped by 13 percent. Those 10 grams of fiber are the equivalent of about one apple and two slices of whole wheat bread, or about half a cup of cooked kidney beans and cooked cauliflower or squash.
In the study, the greatest apparent benefit came from fruit and vegetable fiber. Researchers speculated that eating more fiber-rich foods may lessen breast cancer risk partly by helping to reduce high estrogen levels in the blood, which are strongly linked with breast cancer development.
"From many other studies we know that breast tissue is particularly influenced by carcinogens and anticarcinogens during childhood and adolescence," wrote Walter Willett, Fredrick John Stare Professor of Epidemiology and Nutrition at Harvard Chan School and senior author of the study. "We now have evidence that what we feed our children during this period of life is also an important factor in future cancer risk."
Q and A
Q: Are sweet potatoes better for you than white potatoes?
A: Potatoes come in many different shapes, sizes and colors and offer an array of nutrients at an affordable price. Recent research revealed that potatoes offered the most nutritional bang for the buck, with higher fiber and potassium content at the lowest cost compared to other vegetables. According to the USDA's National Nutrient Database, both white and sweet potatoes are low in sodium and fat, and contain less than 115 calories per cup. They are both good sources of fiber, with about 4 grams per cup. However, each of these tubers shines in different nutritional areas. White spuds are loaded with vitamin C, with 13.6 milligrams per cup and potassium, with 610 milligrams per cup and almost double the B-vitamin folate of their sweet cousin. On the other hand, the sweet potato's golden orange flesh offers a beta-carotene bonus, supplying it with abundant vitamin A (18,869 IU per cup), whereas white spuds contain virtually none. Sweet potatoes prove to be a better bet when it comes to blood sugar control, as they do not raise blood sugar and insulin levels as high as white potatoes do, according to Harvard's glycemic index ranking. The bottom line: Mix and match white and sweet potatoes in moderation in your weekly meals and reap a bounty of nutritional rewards, as well as culinary opportunities that all will enjoy. -- Environmental Nutrition.
Here's a great recipe for a healthy, homemade bar for a snack or lunch box treat. The recipe is from Williams Sonoma, "Healthy In a Hurry."
Chewy Fruit & Nut Bars
1 teaspoon plus 2 tablespoons unsalted butter
1 1/2 cups puffed brown rice cereal
1 cup whole almonds
1/2 cup whole cashews
1 cup dried cranberries
1/2 cup dried apricots, chopped
1/2 cup brown rice syrup
1/4 cup unsalted creamy almond butter
2 tablespoons light brown sugar
1/4 teaspoon salt
Line an 8-inch square baking pan with foil, leaving an inch or so of overhang on 2 opposite edges to use later as a handle. Grease foil with 1 teaspoon butter. In a large bowl, stir together brown rice cereal, almonds, cashews, cranberries and apricots. Set aside. In a saucepan over medium heat, stir or whisk together brown rice syrup, almond butter, brown sugar 2 tablespoons butter and salt until mixture is smooth. Bring to a simmer and cook for 1 minute, stirring constantly to prevent scorching. Immediately pour hot almond-butter mixture over cereal mixture in bowl. Using a wooden spoon, mix until cereal, fruit and nuts are evenly coated and distributed. With lightly buttered hands, press mixture firmly and evenly into prepared pan. Refrigerate until set, about 1 hour. Lift out of pan and transfer to a cutting board. Use a sharp buttered knife to cut into 20 small bars; remove from foil. Stir in refrigerator in an airtight container with sheets of waxed paper between layers, for up to 1 week. Makes 20 bars.
Per bar: 170 calories, 3 grams protein, 20 grams carbohydrate, 9 grams fat, 0 milligrams cholesterol, 2 grams fiber, 40 milligrams sodium