Wednesday, November 23, 2011

Eat your vegetables!

I taught in a public high school for three years before entering agricultural and nutritional graduate studies. In our school cafeteria, a wide array of cooked and raw fresh vegetables was made available to kids. Vegetables were always stationed at the beginning of the buffet line, which coiled around a salad bar. Over and over again, students omitted vibrant green and red colors in order to arrange various shades of white and brown foods on their plates. French fries were a daily staple, often (but sometimes not) accompanied with a side of some sort of breaded or bunned meat.

I found this NYT article to be interesting, entitled “Told to Eat Its Vegetables, America Orders Fries.” Despite millions of dollars and hoards of effort to the contrary, Americans are still undereating vegetables and overeating starches and simple sugars. (2-3 daily servings of meat is actually the only American Dietetics Association recommendation that is properly adhered to by the average American, per a conversation with Stacey Bates, former R.D. for the Texas Beef Council). The proceeding article in Food, Think! will focus more in depth on the American diet and decision-making, but today's article will be about why the order to “Eat your vegetables!” is truly sound advice. 

Vegetables have 4 main benefits (main sources from ADA's website, 

  1. Antioxidants (Vitamins A, C, E & Flavinoids such as color pigments like red lycopene): These compounds are meant in plants to be absorptive of intense energy, such as sunlight. In the human body, they control the reactivity of dangerous compounds such as free radicals that may alter DNA to induce cancerous growth. Several studies have suggested a strong relationship between phytonutrient intake and cancer prevention: Jeffery, E.H., et al. (2006). Diet and cancer prevention: current knowledge and future direction; Lemonick, M.D. (July 19, 1999). "Diet and cancer: can food fend off tumors?"; Go V.L. et al., (December 2004). "Diet and cancer prevention: evidence-based medicine to genomic medicine". Journal of Nutrition; "Diet And Cancer Prevention: New Evidence For The Protective Effects Of Fruits And Veggies". ScienceDaily. December 7, 2007.
  2. B-Vitamins & Folate: essential for growth and creation of new cells and fighting disease. 
  3. Minerals: Calcium strengthens bones and necessary for muscle contraction. It also signals for many cell processes; Iron is necessary for oxygen transport within the body; Magnesium is an essential component of most bodily enzymes which mechanize all sorts of bodily functions; Potassium regulates blood pressure, helps maintain fluid and nutrient equilibrium in almost all cells, among other benefits. 
  4. Fiber: Vegetables offer two types of fiber, soluble and insoluble. Soluble fiber, or pectin, dissolves in the digestive tract into a gelatinous matrix...probiota feast on it within the digestive tract. Insoluble fiber, like soluble fiber, cannot be digested by human digestive enzymes, and stays intact until it reaches the colon where it is also a food source for probiota. 

Soluble Fiber: Our bodies use internal cholesterol to create bile, which is a kind of detergent that is released into the intestine to break down fat, making them possible for absorption. The matrix that soluble fiber forms in the intestine actually traps bile and the fats they transport, preventing the body's reabsorption and recycling of cholesterol, and also the absorption of the fats they carry. This is why oatmeal, having 2 of the 3 recommended daily grams of soluble fiber, is so famous for lowering cholesterol!

Insoluble Fiber: Because of its abrasive, pipe-cleaning effects, insoluble fiber reduces hemorrhoids, provides a vehicle for bodily wastes, and cleanses any harmful substances that adhere to the inside of the colon. Many studies (below) suggest that the benefits of insoluble fiber work to reduce the incidence of colon and rectal cancers by eliminating damaged cells, cleansing the tract from harmful substances, and promoting the growth of new cells. When probiota break down and ferment insoluble fiber in the colon, a metabolic byproduct (a Volatile Fatty Acid, particularly) is released called Butyrate. Butyrate stimulates growth of new, healthy epithelial (colon-lining) cells. Here area few studies that provide a possible link between insoluble fiber and cancer prevention: Trock et al., (April 1990). "Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence". Journal of the National Cancer Institute. Lanza et al., (1992). "Dietary fiber". Micozzi and Moon (1992). Macronutrients: Investigating their role in cancer.

I’m going to make sure my plate is colored with plenty of vegetables this Thanksgiving. What do you Think?