For decades, scientists have argued about fiber's impact on disease rates. American studies often found no links to the prevention of cancer and heart disease, while European studies did. A new Harvard study found dietary fiber eaten in the teenage years and early adulthood significantly decreased breast cancer rate later in life, especially with premenopausal breast cancer, the most dangerous kind. And this result was unchanged by red meat and animal fat, while previous studies have found a significant link.
"Adolescence and early adulthood is a period when breast cancer risk appears to be very important," according to the study.
Several biological mechanisms explain the role of fiber on breast cancer risk. Because eating high fiber foods tends to keep blood sugar at lower levels, insulin levels may be lower. When insulin is higher because of a higher blood sugar level, "insulin-like growth factors," which are associated with higher cell growth and cancer rates, reduce. Also, dietary fiber may lower estrogen levels in the blood by increasing bowel excretion.
Our grandmothers have been extolling the virtues of roughage for generations. Turns out they were right. But the benefit of "roughage" aka fiber, are far more vast than our grandmothers ever realized.
Fiber is mainly carbohydrate, the undigestible part of plant foods - fruits, vegetables, whole grains, legumes and nuts.
All types of fiber were associated with decreased risk, including fiber from fruits, vegetables, insoluble and soluble fibers.
For the first time, scientists have discovered certain fruits and vegetables - and not others - are associated with preventing weight gain over the course of many years regardless of calories, according to a recent Harvard study published in the British Medical Journal. These fruits and vegetables contain a class of phytonutrients called flavonoids, a plant compound with anti-inflammatory and anti-oxidant properties, among other benefits.
"The particular fruits and vegetables associated with less weight gain are rich sources of several flavonoid subclasses, particularly flavonols, anthocyanins, and flavones. Animal models and short term human studies provide evidence for underlying mechanisms that relate flavonoids to weight: several flavonoid subclasses have been shown to decrease calorie intake, increase blood sugar uptake in muscle in humans, and decrease blood sugar uptake in fat tissue in test tube studies. Other studies, predominantly focusing on green tea, a rich source of the flavan-3-ol subclass of flavonoids, provide evidence to suggest that flavonoids may decrease fat absorption, increase energy expenditure, and inhibit body fat synthesis," according to the study.
In the study, anthocyaninins, the blue pigment in many fruits and vegetables, were mainly found in blueberries and strawberries, among others. Flavan-3-ols were mainly from tea, apples, pears, and peppers.
I'm regularly asked, "Is organically grown food better than conventionally grown?" Of course, intuitively, one would believe yes, there must be a difference. But since I always base my recommendations on science, I've been in a bit of a conundrum over answering this question, because there have been so few studies done.
Yes. It's been scientifically verified that organically grown foods improve the environment in many ways. They also contain a lower level of pesticides. But are there nutritional differences? Some studies say yes, some say no.
One recent study of animal meats published in the British Journal of Nutrition found no significant difference in the meats' nutrients, but did find significant differences in the type of fat in the animal meat. Other studies of farm raised fish get similar results. The grass-grazing cows and wild fish contain more omega-3-fatty acids, a healthy fat associated with reduced inflammation and superior health, and less of the unhealthy fats which are correlated with inflammation and cardiovascular disease.
How about fruits and vegetables? I'd like to think there are nutritional differences, but study results are mixed, that is, of the very few studies conducted. One interesting factor which may contribute to positive findings is that plants without pesticides have to work harder to synthesize phytochemicals to protect themselves against the elements. These phytochemicals are good for human health, too.
A plant exposed to more sun versus less sun will produce more phytochemicals, for instance, a pigment, such as lycopene (red), beta-carotene (orange), and anthocyanin to protect itself. Apparently, plants under more stressful conditions, such as exposure to bugs, disease, heat, cold, and sun, protect themselves with phytochemicals ("Phyto" is plant in Greek). Some plants develop a distinctive, strong smell, like plants in the onion family which produce allinase, or in the broccoli family which produce sulphorphane, both potent nutrients which not only protect the plants' health but our health as well.
But the bottom line is: What you eat profoundly affects not only your health, but the environment, too. This is important news because when it comes to environmental issues and halting global warming, many of us feel overwhelmed and helpless. So it’s amazing that something as simple as making better food choices can reduce global warming by lowering greenhouse gases, saving land, and conserving diminishing water and energy supplies.
Your protein choice will make the most significant difference on the environment (and your health). Producing meat requires six to seventeen times more land than growing vegetable protein, 26 times more water. And producing vegetables is up to 50 times more energy efficient than meat production, according to a study in the American Journal of Clinical Nutrition.
Eating vegetable protein will also save your health. Decades of research has found that plants contain compounds (phytochemicals) with potent powers of healing. People who eat a plant-based diet are leaner, have less cancer, heart disease and diabetes.
But when eating more fruits and vegetables, it’s important to consider how and where they’re grown. Environmental resource conservation is reduced if food is transported long distances and grown in large industrial farms which specialize in only one or a few foods. Locally, organically produced food saves water, energy and encourages a region’s unique varieties of fruits and vegetables. Heirloom varieties, for example, have been passed down through generations, have natural resistance to pests, disease and are better able to tolerate local conditions without too much exra energy, pesticides or water.
How you can protect the environment through your food choices:
* Buy seasonally and locally at farm stands and farmers’ markets,
* Eat a plant-based diet,
* Reduce meat consumption,
* Use heirloom varieties, whenever possible,
* Buy organic whenever possible.