By: Mariam Arshad
When you stroll down the cereal aisle in the grocery store, you will notice a wide array of ready-to-eat cereals such as Honey Bunches of Oats, Cheerios, and Frosted Flakes. You will also find hot cereals such as cream of rice, grits, and the age-old classic, oats.
Oats come in a variety of preparations such as steel cut, old-fashioned, and instant. The difference between these preparations comes down to the level of food processing. If we were to arrange these varieties on a spectrum from least processed to highly processed, it would consist of steel cut oats, then old-fashioned oats, then instant oats, and finally, ready-to-eat cereals such as Honey Nut Cheerios.
But what exactly does food processing entail? Food processing of oats involves grinding, steaming, and rolling - depending on the desired outcome. Quick cooking oats, for example, are steamed and rolled into thinner flakes than old-fashioned oats. The oats in Honey Nut Cheerios are processed into a ready-to-eat cereal by milling harvested oats into flour, combining them with other ingredients including sugar, corn starch, oil, and preservatives, and finally toasting them into the crunchy cereal loved by many.
How does this processing affect your blood sugar? Let’s rewind a bit and talk about fiber. Fiber is a type of carb that our bodies cannot digest. It is found in foods like fruits, vegetables, whole grains, and legumes. There are two major types of fiber – soluble and insoluble. Something is soluble if it can dissolve in water. In the body, soluble fiber from foods forms a gel which is thick like honey and can be described as viscous. Carbs from the foods we eat are broken down into sugarswhich circulate in our blood and are eventually stored in our cells with the help of the hormone insulin.
Too much sugar circulating in the blood is a concern, as it is too little. This is where soluble fibers from our diet come into play. Soluble fibers can help lower blood sugar because the viscous gel they form in the digestive tract moves slowly, thereby slowing the digestion of carbs from soluble fiber-rich foods. As a result, the sugars from carb digestion are slowly released in the blood. This means that our blood sugar levels do not rise as quickly when eating foods rich in soluble fiber, which necessitates less of an insulin response.
Now back to food processing. Researchers of a 2019 study examined blood sugar and insulin responses to different levels of oat processing in thirty healthy adults. Three main outcomes were assessed on both blood sugars and insulin: peak rises, peak blood concentrations, and incremental changes from 0-2 and 0-3 hours. Participants consumed one of each cereal over five different days after an overnight fast: old-fashioned oats, instant oats, steel cut oats, Cream of Rice, and Honey Nut Cheerios. Cream of Rice served as a comparison as it does not contain fiber.
The hot cereals were matched for carbohydrates, and the Honey Nut Cheerios were matched with the other cereals for calories. The participants’ blood sugar and insulin levels and peaks were assessed at fasting and at several intervals from 15 minutes to three hours after eating the cereal. The researchers found that steel cut oats, which were the least processed variety [and by extension, containing the most intact soluble fiber], elicited the lowest peak rise and peak concentration in blood sugar and insulin. Blood sugars and insulin levels were lower overall in response to cereal varieties with less processing. Instant oats, which were the most processed of the hot oat cereals, were comparable to Cream of Rice and Honey Nut Cheerios in terms of blood sugar peak rises and concentration, and even higher in insulin peak rise and concentration. As far as incremental changes in blood sugars and insulin, the cereals elicited great variability.
Why does this all matter? Controlling blood sugar is essential to our health and the prevention and management of diabetes. To this end, it is necessary to consider the quality of carbs we consume, not just the amount. Less processed varieties of oats such as steel cut oats and old-fashioned oats can better dampen the rise in blood sugars and insulin since the soluble fiber in these foods is more intact compared to more processed varieties. The observed responses of blood sugar and insulin to processing can help inform your decision of which cereal to consume for maximum nutritional benefit.
