At a time when carbohydrates, specifically grains, have taken a beating by advocates of the Paleo, Atkins, and various other popular diets, you may be wondering if you’re better off going against the grain.
If you are confused about grains, fiber and carbohydrates, you aren’t alone. In fact, the published scientific literature on these topics varies tremendously, depending on the specific population studied, type of food consumed, and if the study was a clinical trial or population-based epidemiological study. Why is fiber important? The fiber found in whole grains, beans, nuts, fruits and vegetables, keeps constipation at bay and improves blood cholesterol and blood glucose levels.
The Science of High-fiber and Whole-grain Choices
Now you may be wondering if you can just skip the whole grains and consume your fiber from nuts, beans and produce. However, a recently published National Institutes of Health study may make you re-think this strategy. This study followed 388,000 people over a nine-year period, examining diet and risk of death from all causes. They found that dietary fiber intake lowered the risk of death from cardiovascular, infectious, and respiratory diseases by 24 percent to 56 percent in men and by 34 percent to 59 percent in women. And, dietary fiber from whole grains was significantly and inversely related to the risk of cardiovascular disease, cancer, and respiratory disease deaths in men and women.
In this study, men and women with the highest intake of dietary fiber from grains, compared to those with the lowest intake, had a 23 percent and 19 percent lower risk of total death respectively. And of course, decreasing your risk of death is nothing to sneeze about.
The results of this study are likely due to multiple factors. Whole grains are packed with antioxidants in addition to several vitamins and minerals that may protect our bodies from free radical damage, a potential cause of chronic inflammation. And, inflammation may contribute to the progression of a number of infectious and respiratory diseases, as well as cardiovascular disease. Also, dietary fiber is associated with improved blood lipid profiles, improved insulin resistance and a decrease in blood pressure. And, dietary fiber also affects the bacteria in your gut. In fact, going on a high-protein, reduced-carbohydrate diet (or even moderate carbohydrate) can wreak havoc on your gut health.
In one study examining the effects of this type of diet on colonic health, 17 obese men and women were given a weight maintenance diet (85 grams protein, 116 grams fat, and 360 grams carbohydrate per day) for seven days, followed by four weeks on a high-protein, moderate-carbohydrate diet (139 grams protein, 82 grams fat, 181 grams carbohydrate per day) or a high-protein, low-carbohydrate diet (137 grams protein, 143 grams fat and 22 grams carbohydrate per day) in a crossover design. After just four weeks, both the moderate- and the low-carbohydrate diets resulted in a significant decrease in metabolites that protect us from cancer and an increase in hazardous metabolites.
The research on whole grains is pretty convincing. So, you may be wondering why so many people cut them out of their diet or claim that our carbohydrate consumption has fueled the obesity epidemic. Cutting carbohydrates out or specifically picking on certain types of carbohydrates such as wheat is an easy strategy that requires no thought. When faced with a 500-calorie grilled chicken sandwich with lettuce and tomato, your only option is to eat the 200-calorie piece of chicken, dropping your portion of carbohydrates consumed and overall calories.
But the problem isn’t the grains, but instead the fact that we abuse them in the United States where “more is better” is our philosophy. According to the U.S. Department of Agriculture, our average daily consumption of grains increased from approximately 430 calories per day in 1970 to 625 calories per day in 2008. Not only did our grain servings morph, but 90 percent of the grains we consume are refined.
A Nation of ‘Supersized’ Guts and Butts
This American chow-down shouldn’t be too surprising when you take a look around. First, food is everywhere in the U.S. and we can get it at any time of the day. In the 1970s, Blockbuster didn’t exist; now we can get supersized boxes of candy at a store whose primary business has nothing to do with food. In addition, our portions have morphed (as did our plate and bowl sizes), so supersize became the “norm” and anything less than an overflowing plate tricked us into thinking we were being ripped off.
And finally, we often consume multiple carbohydrates in one meal. Sit down at any restaurant and chances are you may start off with free chips or bread— and if these aren’t available, diving into a carbohydrate-based appetizer is a no-brainer. And, depending on what you choose for a main meal, chances are it will also contain multiple servings of carbs (chicken fajitas or warm tortillas served with a side of rice for instance). In our “more-for-less” thinking, it may seem like we are getting a great deal for our dollar but in fact, rice, corn and wheat are cheap (partly because tax dollars subsidize their production via the Farm Bill). So that meal deal for $8 isn’t really a steal after all.
Though consuming some grains in our diet is a good thing, too many grains can be harmful, especially for people who are overweight or obese. And, back in the 1990s, we went carb-crazy, consuming just about anything that said “fat-free” on the package. By replacing the fat in our diet with refined carbohydrates, we were hampering our diet more than helping it.
A high-carbohydrate diet, especially one loaded with refined carbohydrates and sugars, can increase blood triglycerides and decrease our good cholesterol (HDL). And, overweight and obesity increase the likelihood that you’ll develop abnormal blood lipids on a higher carbohydrate diet. On the contrary, limiting refined grains can improve blood lipids as well as blood pressure.
To Your Health and Long Life!
A great example of this approach is the DASH diet (Dietary Approaches to Stop Hypertension). This diet found that simply replacing saturated fat and added sugars in our diet with fruits, vegetables and low-fat dairy products resulted in significant decreases in blood pressure and LDL cholesterol with no effect on triglycerides.
The DASH diet is by no means a low-carbohydrate diet and it includes grains, but it emphasizes whole grains. And, in addition to portion distortion, refined grains may be part of the problem. In a study examining three servings per day of whole grains versus refined grains over a three-month period, the participants who consumed whole grains had lower blood pressure than those who consumed refined grains.
Another study, this one conducted in over 58,000 Japanese men and women aged 45-75, also found an issue with refined grains— this time in the form of white rice, a major staple of the Japanese diet. After examining white rice intake and the risk of type 2 diabetes, the researchers found that white rice was associated with an increase in the incidence of type 2 diabetes in Japanese women and a positive association in men who didn’t engage in strenuous physical activity.
So what’s the bottom line? Fiber is good for our health. And if grains are consumed, the majority of them should be whole grains, not refined carbohydrates and products made from them. However, all Americans should be mindful of the serving sizes they need, based on their total calorie intake, physical training program and state of health. Those who are overweight, obese, have Type 2 diabetes, insulin resistance, PCOS or The Metabolic Syndrome may benefit from cutting their total carbohydrate intake and limiting the amount of carbohydrates they consume in one sitting.
If you cut your carbohydrate intake though, be sure the grain-based carbohydrates you consume are whole versus refined, and that you meet the U.S. Dietary Guidelines recommendation of 14 grams of fiber per every 1,000 calories consumed.
USDA 2007 Census of Agriculture, United States Summary and State Data. Volume 1, Geographic Area Series, Part 51.
Nanri A, Mizoue T, Noda M, Takahashi Y, Kato M, Inoue M, Tsugane S. Rice intake and type 2 diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study. Am J Clin Nutr, 2010; 92(6): 1468-77.
Russell WR, Gratz SW, Duncan SH, Holtrop G, Ince J, Scobbie L, Duncan G, Johnstone AM, Lobley GE, Wallace RJ, Duthie GG, Flint HJ. High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health. Am J Clin Nutr, March 9, 2011.
Park Y, Subar AF, Hollenbeck A, Schatzkin A. Dietary fiber intake and mortality in the NIH-AARP diet and health study. Arch Intern Med, 2011 [epub ahead of print].
Tighe P, Duthie G, Vaughan N, Brittenden J, Simpson WG, Duthie S, Mutch W, Wahle K, Horgan G, Thies F. Effect of increased consumption of whole-grain foods on blood pressure and other cardiovascular risk markers in healthy middle-aged persons: a randomized controlled trial. Am J Clin Nutr, 2010;92: 733-740.