1. What is a carbohydrate?
2. What are common carbohydrate sources?
3. What are refined carbohydrates?
4. What are examples of refined carbohydrates?
5. History of refined carbohydrates
6. Association between refined carbohydrates and type 2 diabetes
7. Conclusion
Today's subject matter is carbohydrates, specifically, refined carbohydrates. We are going to talk about what carbohydrates are, how they impact your blood sugar, and how this affects you and your susceptibility to diseases like type 2 diabetes and coronary artery disease. There is a lot of buzz recently with "low carb", "keto", or "carnivore" diets which severely reduce or eliminate entirely carbohydrates. Perhaps you know someone who is a diabetic. Regardless, carbohydrates are the common denominator in many of these groups and we are going to dive into several facets of the carbohydrate story.
What is a carbohydrate?
Let's start with simply defining a carbohydrate. A carbohydrate is a molecule made from carbon, hydrogen, and oxygen that is found in many of our food sources like fruits, vegetables, grains, and legumes. Plants make carbohydrates by converting water and carbon dioxide with the presence of sunlight (this is photosynthesis)to create sugar molecules called carbohydrates. We eat these plant materials and digest the carbohydrates in them in order to produce energy.
Let's me be clear up front. Not all carbohydrates are the same. Some are long, some are short. Some raise your blood sugar quickly, others do not. Regardless, our bodies are capable of breaking many of these carbohydrates down in order to make energy.
What are common carbohydrate sources?
The first thing that might come to mind when you think of carbs might be bread and pasta. While these certainly fall into the category of carbohydrates, carbohydrates sources can be found naturally in the fruit, vegetable, legume, and grain families. Examples include honey, apples, oats, pumpkin, kidney beans, cashews, wheat, rice, corn, and blueberries to name a few. Carbohydrates can also be processed, refined, or extracted like in the case of sugar cane or high fructose corn syrup (HFCS). Fat sources like olive oil, coconut oil, and butter or protein sources like beef, chicken, pork, or salmon are not carbohydrate sources.
What are refined carbohydrates?
Now what's the difference between naturally occurring carbohydrates like a sweet potato, and refined carbohydrates like refined all-purpose wheat flour or high fructose corn syrup produced from corn? First off, it takes human work to modify these foods from their natural state into their man-made state. Wheat is removed from the chaff and ground into a powder. Sugar cane is crushed to extract the juices out of it and the excess water is boiled off. For those of you who have tried your hand at tapping a maple tree, you know that it takes about 40 gallons of sap flowing from the tree to make 1 gallon of maple syrup when boiled down. Concentration is a very important piece to this puzzle. How much modification happens to a sweet potato when you dig it out of the ground or pluck a cherry tomato off the vine? None. You have preserved it in its natural state, and this makes a big difference as you will soon see.
What are examples of refined carbohydrates?
Refined carbohydrates include processed grains like wheat flour and the products made from it including but not limited to pasta, spaghetti, sandwich bread, donuts, crackers, cookies, pies, rolls, bagels, pastries, pizza, noodles, brownies, cakes, and tortillas. Refined carbohydrates also include soft drinks like sodas, sweetened teas, lemonade, sports drinks, Gatorade, or coffee creamer. Sweetened products that use high fructose corn syrup, cane sugar, or just plain sugar fall under this category too. This list is extremely expansive from candies, sweets, chocolates, gummies and fruit snacks to kit-kats and ice cream. Even "healthy" items like yogurt, sweetened almond milk, ketchup, mayonnaise, and peanut butter you will find riddled with these ingredients. Don't believe me, look for yourself! You will be surprised to find how many everyday items contain some form of refined carbohydrate.
History of Refined Carbohydrates
In the 20th century, we have refined our refining process of grains. By refining grains like wheat into white flour, this increases the caloric density by greater than 10%, reduces the fiber by 80%, and reduces the amount of protein by nearly 30% (1).
Corn syrup was essentially nonexistent at the turn of the 20th century. By 1967, high fructose corn syrup (HFCS) was commercially produced. At this time, the fructose concentration of the corn syrup was roughly 15%. With improved technology, manufacturers were able to produce a corn syrup of 42% fructose, and with further work, this was increased to 55%, and ultimately 90%! In 2002, high fructose corn syrup made up roughly 56% of the sweetener market and today it makes up greater than 20% of total daily carbohydrate intake and 10% of daily total energy intake. Furthermore, the use of caloric sweeteners increased by a whopping 86% between 1909 and 1997 (1).
Between 1980 and 1997, the percentage of dietary carbohydrate consumption increased from 48 to 54% of total energy intake. During this same time, the amount of dietary fat consumed dropped from 41 to 37% of total energy intake. Okay, no big deal right? Well, during this time the prevalence of type 2 diabetes increased by 47% and the prevalence of obesity increased by 80% (1)! What is equally alarming is that between 1935 and 1996, the prevalence of type 2 diabetes increased by about 765%. At the time of publication for this study (2004), it was estimated that greater than 16 million Americans were living with type 2 diabetes. As of 2017, the CDC (Center for Disease Control and Prevention) released a press release on the diabetes growth rate. The report states that as of 2015, 30.3 million Americans, which makes up 9.4% of the U.S. population have diabetes and 84.1 million have pre-diabetes (2). Now those are numbers to bat an eye at.
Association between refined carbohydrates and type 2 diabetes
What was the kicker in the previously mentioned study? Certainly by eating just a few more calories a day from carbohydrates couldn't be so detrimental could it? This is where we have to look at the source of the carbohydrates. The study states that they "found a strong association between an increased consumption of refined carbohydrates in the form of corn syrup, a decreased consumption of dietary fiber, and an increasing trend in the prevalence of type 2 diabetes in the United States during the 20th century. Furthermore, our data are consistent in that obesity and the prevalence of diabetes increased proportionately to the increase in consumption of refined carbohydrates in the Unites states" (1).
Lastly, there is evidence that a diet with a high glycemic load (which is a diet that is high in refined carbohydrates) increases risk for obesity, glucose intolerance, dyslipidemia, type 2 diabetes, and coronary artery disease (1). The next blog will give you the details of what is happening in the body when we ingest these refined carbohydrates and their contribution to disease.
In the Part 2 series of this blog, we will be talking about the normal role of insulin and how our food choices may contribute to the development of fatty plaques in the arteries.
Conclusion
Carbohydrates are molecules made through photosynthesis in plants. We consume carbohydrates from food sources like fruits, vegetables, legumes, and grains. Due to innovation, we have been able to refine grains like wheat into white flour and produce sweeteners like high fructose corn syrup or refined sugar (4). These are examples of refined carbohydrates which can be found in many of our modern foods including breads, pastas, desserts, soft drinks, candies, sweetened products, and even ordinary foods like ketchup, mayonnaise, and peanut butter. The prevalence of type 2 diabetes and pre-diabetes has been increasing significantly over the past several decades (2). It is likely a good idea to avoid the consumption of refined carbohydrates due to their close association with an increased prevalence of type 2 diabetes, obesity, and coronary artery disease among others (1).
1. Gross, Lee S et al. 2004. Increased consumption of refined carbohydrates and the epidemic of type 2 diabetes in the Unites States: an ecologic assessment. The American Journal of Clinical Nutrition. 79(5): 774-779.
2. CDC Centers for Disease Control and Prevention. 2017. New CDC report: More than 100 million Americans have diabetes or prediabetes. Retrieved: May 15, 2019. From: https://www.cdc.gov/media/releases/2017/p0718-diabetes-report.html
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