The National Health and Nutrition Examination Survey (NHANES) found that daily consumption of starchy snacks made from flour was associated with a 50 percent increased risk of death from all causes and a 44-57 percent increased risk of death from a heart attack (J of the Am Heart Assoc, Jun 23, 2021;0:e020254). This study of 21,503 North Americans, with 149,875 person-years of follow-up, also found that lunches based on refined grains were associated with a 44 percent increased risk of cardiovascular death. In contrast, eating fruits, vegetables or dairy was associated with a 34 percent reduced risk of death from a heart attack, and eating a vegetable-based dinner was associated with a 23 percent reduction in heart attacks and a 31 percent reduction in deaths from all causes.
The Prospective Urban Rural Epidemiology (PURE) study found similar results (Brit Med J, Feb 3, 2021;372:m4948). This study followed 137,130 participants in 21 countries for 16 years and found that eating more than seven servings of refined grains per day was associated with a 27 percent increased risk for early death, 33 percent increased risk for heart disease and 47 percent increased risk for stroke. The study found no harmful effects from whole unground grains.
Fiber to Control Weight and Lower Risk for Type II Diabetes
There is no debate in the scientific community that people should eat lots of plants that have not had their fiber removed. A review commissioned by the World Health Organization (WHO) of 185 prospective studies and 58 clinical trials, covering 4600 adults, shows that for every 8-gram/day increase in dietary fiber, there was up to a 31 percent decrease in deaths from all causes, a 30 percent decrease in deaths from heart attacks, a 22 percent reduced risk of stroke, and a 16 percent reduced risk of diabetes, colorectal cancer or breast cancer (Lancet, Jan 10, 2019). See More Fiber from Whole Foods is Better
Fiber is millions of sugars bound together. All carbohydrates are single sugars or combinations of sugars; for example, glucose is a single sugar, and sucrose or common table sugar is a double sugar. Starch contains thousands of sugar molecules bound together, while fiber’s millions of sugars are bound together so tightly that you cannot break them apart in your intestines. Only single sugars can pass from your intestines into your bloodstream, so the double, triple, and other combinations of sugars and all starches must first be split into single sugars before they can be absorbed. These reactions occur so rapidly in your intestines that most starches cause rises in blood sugar that are not much lower than those from single sugars. Frequent high rises in blood sugar increase risk for type II diabetes.
Humans cannot absorb fiber in their upper intestines because they lack the enzymes necessary to break down fiber into single sugars. Therefore, fiber passes unabsorbed in the intestines to the colon where bacteria do have the enzymes to break down some of the fiber. There are two types of fiber: soluble and insoluble. Insoluble fiber cannot be absorbed and passes from your body in your stool, helping to prevent constipation. Colon bacteria are able to break down soluble fiber into short chain fatty acids (SCFAs) that reduce inflammation, helping to prevent diseases and prolong lives. SCFAs lower high blood sugar, high cholesterol, high insulin, and high blood pressure, and help to prevent heart attacks and strokes by reducing the risk for forming clots. A healthful diet includes large amounts of the foods that contain both types of fiber — fruits, vegetables, whole grains, beans, nuts and other seeds.
Why Whole (Unground) Grains are Healthful
Whole grains are seeds of grasses that are as hard as little stones, so they have to be cooked or ground up before you can eat them. Each whole grain (seed) has three parts: bran, germ and endosperm.
• The outer coating of whole grains, called bran, is a rich source of fiber.
• The germ (a tiny bump at the bottom of each seed that would grow into a new plant if sprouted) contains vitamins, healthful fats, phytochemicals, minerals and other nutrients.
• The endosperm is the starchy inner part of the seed that would be the energy source for the baby plant.
When whole grains are cooked, chewed and swallowed, the starchy inner part of the seeds is digested very slowly and does not cause a high rise in blood sugar. However, when grains are ground into a powder (flour), the starches are quickly digested and broken down into single sugars, which can cause high rises in blood sugar.
When mills grind whole grains into flour, they usually strip away the bran and the germ, saving only the starchy endosperm. They remove the germ because it is full of fat that hastens spoilage. Ground whole grains with the germ left in can be kept on the shelf only for a short time, while flour that has had the fatty germ removed can be kept for years. So most foods made from flour are very low in vitamins, minerals, fiber and other nutrients, and no matter how many vitamins they add back in, it is not the same healthful food. See Is It Really Whole Grain?
The most healthful snacks are whole fruits, vegetables, nuts, and snacks made from whole grains. Particularly if you are trying to control your weight, are diabetic or have a problem with constipation, I recommend that you use whole (un-ground) grains instead of products made from flour, even if the label claims that they are “whole grain.” See Diana’s simple instructions for cooking whole grains and her many delicious, easy recipes.
Dr. Gabe Mirkin is a Villager. Learn more at www.drmirkin.com