A bagel or bowl of cereal is common for breakfast, followed by a sandwich or burger for lunch. Dinner often stars pasta, pizza, or a casserole as the main dish. There is one ingredient that lurks in nearly every American meal.

Wheat. It’s the main ingredient in bread, the most purchased packaged food in the United States.1 It plays an integral role in many diets, but if not correctly consumed, it can damage the human body. The harmful effects include increased risk of weight gain, cardiovascular disease, and even cancer.2 To avoid adverse effects while reaping the benefits wheat offers, three factors should be considered: wheat type (whole-grain or refined), the portion size, and the accompanying ingredients.

Whole Grains Instead of Refined Grains

Guidelines by the United States Department of Agriculture (USDA) recommend Americans consume whole-grain rather than refined wheat. Currently, the average consumption of whole-grain foods is approximately one serving a day, falling short of the recommended three servings.3 Wheat grains are divided into three parts: endosperm, germ, and bran (Figure 1). Whole-grain wheat grains have the germ and bran intact. In contrast, refined grains that have the bran and germ separated from the starchy endosperm comprises 80% of the grain. Unfortunately, this processing robs wheat of the majority of its nutrients, which are concentrated in the bran and germ.

Whole grain wheat has nearly ten times more dietary fiber, five times as many vitamins and cancer-preventing phenolic compounds, and three times as many essential minerals including zinc, iron, and selenium (Table 1).

The extra dietary fiber of whole-grain wheat itself is a compelling reason to choose it over refined wheat. Increased consumption of dietary fiber has been observed to improve cholesterol concentrations, lower blood pressure, and aid in weight loss. These effects all reduce the risk for coronary heart disease, the leading cause of adult deaths in the United States.4 High-fiber foods facilitate metabolic effects and control caloric intake by increasing satiety. Dietary fiber, consisting of insoluble and soluble components, promotes gastrointestinal health as a probiotic for beneficial bacteria in the colon. Both fibers also provide cardiovascular benefits by lowering “bad” cholesterol, or LDL.

In the broader context of a person’s entire diet, high-fiber foods often have lower energy density and take longer to eat. These two traits promote satiety, curbing consumption of potentially unhealthy foods and lowering total caloric intake. Eating refined wheat, such as white bread and pasta, causes one to not only forego nutrients, but also consume more calories before feeling full. Overconsumption of calories coupled with physical inactivity are major risk factors leading to heart disease and obesity.5

Control Portion Size

In addition to considering what type of wheat one eats (e.g., wholewheat instead of white bread for toast in the morning), an equally important factor is quantity. Feasting upon large portions of wholegrain wheat regularly results in damaging spikes in blood sugar that can lead to an chronic state of Type 2 diabetes.6 Since diabetes is the leading cause of kidney failure in the United States and doubles the risk of stroke, its correlation with consumption of refined wheat is important to understand.7

The biochemical phenomenon underlying this link is called insulin resistance. Insulin is a hormone stimulating various tissues to store glucose from the blood as glycogen. When carbohydrates are digested, they are broken down into glucose, which is transported into the bloodstream, consequently increasing blood sugar levels. This causes pancreatic beta cells to synthesize insulin to convert the increased glucose into glycogen. When the body does not perform these functions well, the resulting condition is Type 2 diabetes.

Even though the USDA advises adding whole-grain wheat to one’s diet, USDA guidelines do not account for the spiking effect on blood sugar when a large portion is eaten in a short time frame. Their guidelines use a rating system called the glycemic index (GI) that is widely utilized in nutrition studies as a quality standard of carbohydrate foods.8 Wonder®, fully enriched white bread, has a GI of 71 while bread made of 80% whole-grain and 20% refined wheat flour has a GI of 52.8 In practical terms, these GI values indicate a 70% increase in blood sugar compared to the blood sugar increase caused by a comparable amount of pure glucose. Likewise, whole wheat bread causes an increase in blood sugar 52% of that caused by glucose. Based on the aforementioned pathogenic contribution of blood sugar spikes, the lower GI of whole-wheat bread quantitatively demonstrates its superiority over white bread.

However, consider the following: the Twix candy bar has an even lower GI of 44. Watermelon has a GI of 72. How does this make sense? The glycemic index fails to account for realistic portion sizes. When the foods are empirically tested on people for their effects on blood sugar, the quantities eaten are equivalent to 50 grams of carbohydrates. Three-quarters of a king-sized Twix bar constitutes 50 grams of carbohydrate, but so do 5 cups of diced watermelon. This difference in volume is due to the fiber and water content of watermelon.

Realistically, a person is likely to eat a whole king-sized Twix bar or one cup of diced watermelon in one sitting. Adjusting for actual serving sizes and assuming linearity, the Twix bar has what is now called a glycemic load (GL) of 58.7 and watermelon a GL of 14.4. As a more relevant implementation of GI values, glycemic load emphasizes control of portion sizes in eating carbohydrates. The GI value of whole-grain wheat is always lower than refined wheat vary, but the difference is small enough that one cup of refined flour pasta might be better than 2 cups of whole-wheat flour pasta in preventing Type 2 diabetes.

Watch Out for Accompanying Ingredients

The final factor to consider is that wheat is rarely eaten alone. In the processing and cooking to make it edible, wheat is nearly always mixed with other ingredients that are potentially harmful. Most breads, pastas, pancakes, cereals, and other wheat products have at least five ingredients trailing behind the primary wheat ingredient, which are broadly classified as preservatives, sweeteners, emulsifiers, leavening agents, flavor enhancers, and dough conditioners. All of these additives to wheat affect short-term feelings after consumption as well as long-term effects on the body. In particular, one should avoid partially hydrogenated oils and moderate high-fructose corn syrup.

Added as dough conditioners and preservatives, partially hydrogenated oils are considerable factors in coronary artery disease, which causes at least 30,000 premature American deaths per year.9 They contain trans fats, which have been unequivocally linked to lowering “good” high-density lipoprotein (HDL) cholesterol and raising “bad” low-density lipoprotein (LDL) cholesterol. Although large companies have removed trans fats, including partially hydrogenated oils, from foods such as Kraft’s Oreos in response to mounting criticism beginning in 2005, numerous food companies still include partially hydrogenated oils in their wheat products. For example, cake mixes, packaged baked goods, and peanut butter are commercially made with partially hydrogenated oils on a regular basis because they simplify manufacturing and reduce costs while increasing the final product’s shelf life. Manufacturers obfuscate this addition by stating the trans fat content of foods as “0g” on nutrition labels. This is allowed because 0.5 grams of trans fat is one serving. However, less than 0.5 grams of trans fat per serving can accumulate when consuming multiple servings of foods such as chips or crackers. Instead, check for the words “partially hydrogenated” or “shortening” in the ingredients list.

While partially hydrogenated oils are conclusively life-threatening, high-fructose corn syrup (HFCS) is a controversial additive. Manufacturers favor the use of HFCS as a sweetener in wheat products due to lower cost, sweeter taste, and higher miscibility. Scientists hypothesize that corn-derived sugar has endocrine effects that lead to obesity, Type 2 diabetes, and metabolic syndrome.8 Insulin and leptin are key hormone signals that regulate a person’s sense of hunger, but consumption of high-fructose corn syrup depresses these internal signals from controlling calorie intake. Another consequence of foods sweetened with HFCS is plaque buildup inside the arteries.10 Nearly any sweet good made from wheat will likely contain HFCS. Although data about its health effects are still inconclusive, HFCS should be avoided.

Being a health-conscious consumer of wheat can mean significant changes in daily choices of which foods to eat and how to eat them. Whole grains provide more fiber and life-boosting nutrients than refined grains, but accompanying ingredients in available food choices need to be considered as well. More importantly, the impacts of wheat on blood sugar need to be controlled by consuming a commensurate amount of fruits and vegetables. Awareness and application of these principles are the main steps to avoiding the bad and getting the good of wheat.

References

  1. Nielsen Homescan Facts, The Nielsen Company. http://www.marketingcharts.com/television/nielsen-issues-us-top-10-lists-for-2007-2700/nielsen-2007-top-10-cpg-purchased-us-homes.jpg/(Accessed Jan. 15, 2013).
  2. Slavin, J. L. Amer. J. Clin Nutr. 1999, 70, 459S-63S.
  3. Cleveland, L. E. J. Amer. Coll. Nutr. 2000, 19, 331–8.
  4. Anderson, J. W. Nutr. Rev. 2009, 67, 188–205.
  5. Swinburn, B. Public Health Nutr. 2007, 7, 123–46.
  6. Liu, S. J. Amer. Coll. Nutr. 2002, 21, 298–306.
  7. World Health Organization: Diabetes Fact Sheet, Media Centre. 2012 http://www.who.int/mediacentre/factsheets/fs312/en/index.html (Accessed Jan. 15, 2013).
  8. Foster-Powell, K. Amer. J. Clin Nutr. 2002, 76, 5–56.
  9. Ascherio, A. Amer. J. Clin Nutr. 1997, 66, 1006S–10S.
  10. Stanhope, K. Amer. J. Clin Nutr. 2008, 88, 1733S-7S.
  11. General Mills. What is Whole Grain, Anyway? Demystifying Whole Grains. http://wholegrainnation.eatbetteramerica.com/images/content/facts_seed.jpg (Accessed Jan. 15, 2013).
  12. Thompson, L. U. Contemp. Nutr. 1992, 17.

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