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What’s New and Beneficial About Oats
According to the National Health and Nutrition Examination Survey from 2009-2010, consumption of oatmeal accounts for about 20% of all whole grains consumed by U.S. adults! This percentage was virtually identical to the percentage of whole grains provided by all cold cereals combined. It was also not far behind the percentage of whole grains provided by all breads and rolls. In short, oatmeal is playing a very prominent role in intake of whole grains by adults in the U.S…
Both oats and oatmeal may provide us with special digestive benefits, partly in connection with their ability to increase the viscosity of our digestive tract contents. “Viscosity” refers to the thickness of the contents and their likelihood of flowing either too quickly or too slowly through our digestive tract. Too little viscosity means too quick of a flow. And along with too quick of a flow comes increased potential difficulty with blood sugar regulation. For this reason, it is very helpful for our foods to provide us with substantial viscosity so that these foods can pass through the upper part of our GI tract (and especially our small intestine) in a healthy way. Intake of oats and oatmeal has been associated with optimal levels of viscosity in which it becomes easier for food to pass through our upper digestive tract and improve our blood sugar regulation.
Healthy passage of oats through our digestive tract has also been linked to an improved sense of fullness when we eat this popular grain. In several studies, consumption of oatmeal has been associated with an increased feeling of fullness after being consumed, and the viscosity of the oatmeal seems to be important for this feeling to occur. Also important in this process may be a unique carbohydrate (called beta-glucan) that is present in oatmeal. In one recent study, oatmeal breakfasts (consisting of approximately ½ cup of dry oatmeal in 1 cup of water and microwaved for 2 minutes) were found to result in an improved sense of fullness (as well as a decreased desire to eat) at both one and two hours following the breakfast meal.
Smaller waist circumference, lower body mass index (BMI), and decreased risk of metabolic syndrome in adults have all been associated with oatmeal intake in recent studies. All of these measurements are associated with lower risk of health problems, including risk of obesity. As a general rule, the volume of oatmeal in these encouraging studies has been approximately 1 cup cooked, with an average fiber content of 4-5 grams. We mention the fiber content of oatmeal in this context because oat fiber has been shown to play a role in these health benefits. Also notable in this context are two unique nutrients found in oats: (1) beta-glucans, which are polysaccharide carbohydrates, and (2) steroidal saponins (including avenacoside A,1 and avenacoside B,2), which are sugar-related (glycoside) molecules found mostly in the bran portion of the oats.
Beta-glucans (mentioned above) have become a special area of research focus in the relationship between oat intake and improved blood sugar regulation. While some foods that we eat can cause abrupt increases in our blood sugar level following their consumption, the beta-glucans found in oats help prevent these abrupt increases when we eat oats. Specifically, between 3-6 grams of beta-glucans per serving of oats seem necessary to provide this moderating effect on our blood sugar level. We have seen one recent meta-analysis of six studies in this area (“meta-analysis” means that the results of multiple studies were statistically combined together in order to produce a more powerful statistical analysis) that showed lower levels of hemoglobin A1C (a blood test often used to assess blood sugar control over a three-month period) following daily consumption of approximately 1 cup cooked oatmeal at breakfast.
When taken as a group, the above studies on oats and oatmeal were one important factor in our decision to include oatmeal in the majority of breakfasts in our WHFoods 7-Day Meal Plan.
Health Benefits
Oat’s Digestive Support
Once foods are eaten, not all of them have an equally supportive impact on our digestive tract. For example, when eaten in large amounts, food with disproportional amounts of fat can slow down our digestive process excessively, including the rate of that foods pass out of our stomach (known as the rate of emptying). Foods that contain disproportional amounts of simple sugars and simple starches can work in the opposite direction, speeding up the digestive process and challenging our blood sugar regulation. By contrast, oats are a food that seems to provide us with unusually helpful digestive support.
A key focus in studies on oats and digestive support has been the unique fibers known as beta-glucans. Water-soluble fibers, beta-glucans support our digestion in two basic ways.
First, beta-glucans increase the “viscosity” of our food contents when they are present in our upper digestive tract. While “viscosity” is a measurement that generally refers to thickness, the idea of viscosity actually involves more than just thickness. When a substance is “viscous” it is not only thick but it is also resistant to flow. Honey and molasses are examples of viscous fluids that take time to pour out of a bottle or jar. Compared to non-viscous fluids like water, these viscous fluids take much longer to pour out and be emptied from the container in which they reside. The beta-glucans in oats appear to have this same type of effect in our small intestine. They allow our food to keep moving through our digestive tract, but they also help regulate the pace by slowing it down and allowing more time for nutrient digestion and absorption.
The increased viscosity of our GI contents may also be accompanied by more engagement of the smooth muscles that surround our small intestine, as well as by the release of digestion-related hormones. This hormone release may include peptide YY and glucagon-like peptide-1 (GLF-1), which are associated with increased feelings of fullness and satisfaction with food. So as you can see, there are a variety of factors that fall into this “digestive support” category when oats are present in the upper portion of our GI tract.
The digestive tract support provided by oats extends to our lower GI tract as well. In our large intestine (colon), oats—including their beta-glucans—get fermented by intestinal bacteria. This fermentability of oat fibers like beta-glucans not only helps maintain healthy bacterial populations in our large intestine, but it also provides the release of short chain fatty acids from these fibers that can provide energy for our intestinal cells.
Researchers have linked both aspects of digestive tract support—increased viscosity in the small intestine and fermentability in the large intestine—to better regulation of insulin, blood sugar, and cholesterol. While these health benefits have sometimes been associated with particular amounts of beta-glucan in oats, there remains a good bit of debate about the exact amount of beta-glucan that is needed. Most studies suggest that 1-2 grams of beta-glucan per serving of oats is not sufficient to provide optimal benefits, and that a more desirable range for beta-glucan intake falls between 3-6 grams per serving. Unfortunately, however, more research is needed before a firm conclusion can be reached about these beta-glucan amounts. More research is also needed about specific varieties of oats and variations in beta-glucan content. Still, the overall research is very clear about the digestive support provided by this unique grain.
Blood Sugar Support Provided by Oats
Although mentioned earlier in this profile, it’s worth singling out blood sugar support as a special health benefit provided by oats. Of course, healthy regulation of blood sugar would be expected from most any whole food that provided us with a substantial amount of protein and fiber. Both of these macronutrients can be helpful in stabilizing our blood sugar because both help moderate the passage of food through our GI tract and engage our digestive processes in a balanced way. Interestingly, you will not find oats in our Top 25 WHFoods for either protein or fiber; therefore, they are not an especially concentrated source of either macronutrient. Yet, they are a significant and balanced source, with ¼ cup of dry unprocessed oats typically providing us with 6-7 grams of protein and 4-5 grams of fiber. Importantly, the fiber in oats is split between soluble and insoluble, providing us with digestive benefits from both fiber types. And equally important, the soluble fiber in oats includes their beta-glucans.
Researchers are not entirely clear about all of the connections that exist between oat intake and blood sugar regulation. All studies point to an important role played by the soluble fiber found in this grain and the beta-glucans that are contained within this soluble fiber component. Also involved may be minerals like manganese (oats are the number 2 source of manganese at WHFoods), the B vitamins they contain (as they play a role in glucose metabolism), and oat saponins, including avenacoside A,1 and B,2. Perhaps it is the unique combination of all these factors in oats that result in the blood sugar support seen in research studies. Intake of oats and oatmeal has repeatedly been shown to improve after-meal (postprandial) blood sugar and insulin levels. In addition, healthy levels of hemoglobin A1C have been associated with intake of both oats and oatmeal. (Hemomglobin A1C is a form of the key protein in our red blood cells—hemoglobin—in which the protein gets linked up with a sugar molecule through a process called glycosylation. If an overly high percentage of our hemoglobin proteins begin to take this form, healthcare providers begin to suspect problems in glucose and insulin metabolism. Since our red blood cells live for approximately three months, hemoglobin A1C levels are viewed as representing the degree of blood sugar stability over a three-month period. In persons at risk for blood sugar problems, intake of both oats and oatmeal have been associated with healthier levels of hemoglobin A1C—which researchers consider evidence of blood sugar support provided by the intake of this grain.
One final issue that we would like to address regarding oats and blood sugar is glycemic index (GI). Although you will find a more detailed description of this issue in the Description section of this profile, we think that it is important to point out that the GI values that we have seen for old-fashioned rolled oats and steel cut oats are significantly lower than the values that we have seen for instant oats. The overall GI range for old-fashioned rolled oats and steel cut oats is 55–70. By contrast, the overall GI range for instant appears to be much closer to 70–80. At WHFoods, we treat 55 or below as “low GI;” 56–69 as “medium GI;” and 70 or above as “high GI.” So you can see that old-fashioned rolled oats and steel cut oats fall into the low or medium GI range, while instant oats fall into the high range. For this reason, old-fashioned or steel cut oats (versus instant oats) would be expected to provide you with better blood sugar support than instant oats.
Oats’ Cardiovascular Support
Strong intake of fiber—including both soluble and insoluble fiber—has long been associated with decreased risk of cardiovascular problems. While the focus in many cardiovascular studies has remained on soluble fiber, research has shown cardiovascular benefits for both fiber types. Soluble fiber—just like its name suggests—is especially “friendly” toward water. Soluble fibers can take on water, swell, and hold water. This characteristic of soluble fiber can lead to improved viscosity in our small intestine contents as described earlier in this profile. As a result of this improved viscosity, we get improved digestion and absorption of nutrients, including some of the key cardiovascular-support nutrients present in oats. These nutrients include multiple B vitamins, as well as the minerals magnesium and zinc. Within the soluble fiber portion of oats are found beta-glucans, and intake of these unique polysaccharide fibers has been associated with decreased levels of total and LDL cholesterol.
In a very large scale study in Denmark involving over 50,000 adults between the ages of 50–64 years, intake of oats has been associated with decreased risk of heart attack (also known as myocardial infarct, or MI). Researchers conducting this study pointed to potential roles for both soluble and insoluble fibers in producing the study results. Some more complicated metabolic processes may also be involved in the cardiovascular benefits related to intake of oats. In particular, researchers have been interested in the ability of oat intake to lessen the risk of excessive inflammation in the blood vessels. The series of events in this area of research has sometimes focused on some unique phenolic, nitrogen-containing molecules in oats called avenathramides. Also of interest have been the oat saponins—primarily avenacoside A,1 and avenacoside B,2. These sugar-related (glycoside) molecules are found primarily in the bran portion of the oat, and like beta-glucan, their intake has been associated with decreased levels of LDL and total cholesterol.
It’s important not to lose the forest through the trees, however, when looking at the cardiovascular benefits of oats and oatmeal. In multiple studies, consumption of this grain has been associated with decreased risk of metabolic syndrome, decreased risk of obesity, lower waist circumference, and lower body mass index (BMI). These findings all point in the direction of cardiovascular support following routine intake of this unique grain. Also worth mentioning in this context are the findings from an analysis of the data from the Nutrition Health and Examination Surveys (NHANES) between 2001—2010 in the U.S. In these analyses, children who ate oatmeal on a regular basis were found to have decreased risk of “central adiposity”, which is the accumulation of excessive body fat in the general abdominal area.
Description
Oats are a member of the grass family of plants (Poaceae) and are often described as a “cereal grass” or “cereal grain.” In this context, the word “grain” refers to the edible seeds of the plant and the word “cereal” refers to the practice of growing these plants in order to obtain their grains. In other words, oats are correctly described as a cereal grain because they are typically grown for their grain (seeds), and they are also correctly described as a “cereal grass” because in addition to being cultivated for their grain/seed content, they also belong to the grass family of plants (Poaceae).
Unlike oats, however, some plants referred to as “cereal grains” do not belong to the grass family. These non-grass grains are sometimes called “pseudograins” or “pseudocereals.” The “pseudograins” or “pseudocereal grains” include buckwheat, amaranth, quinoa, and teff. The cereal grasses include not only oats but also wheat, rye, barley, kamut, spelt, triticale, sorghum, rice, corn (maize), and millet. In its labeling standards, however, the U.S. Food and Drug Administration (FDA) does not differentiate between the cereal grains versus the pseudocereal grains, imply including all of the plants listed above as cereal grains.
In addition to being members of the grass family, oats belong to the science genus/species Avena sativa.
Virtually all oats available in supermarkets have been processed to varying degrees. Minimal oat processing usually includes cleaning (including both screening and air blowing, or aspiration) and hulling. Screening and aspiration are used to remove weed seeds, non-oat grains, and loose (unattached) hulls from the oats. Hulling is used to remove hulls that are still naturally attached to the oats at the time of harvest. (These oat hulls can also be referred to as “chaff.” Once the oats have been cleaned and hulled, they are usually referred to as “whole oat groats” or simply “groats.”) After the cleaning and hulling the oat grains in order to produce the groats, additional processing steps may take place in production of the final oat products.
In the U.S., three types of oat products dominate the marketplace: (1) “old-fashioned” or “regular” rolled oats, (2) quick and instant rolled oats, and (3) steel cut oats. “Old-fashioned” rolled oats usually consist of whole oat groats that have been steamed and rolled to produce their somewhat irregular but recognizably flat and disc-like shape. After rolling, old-fashioned oats are heat-dried to reduce moisture.
Quick and instant rolled oats typically vary from old-fashioned rolled oats in at least one of two ways. They are either rolled into thinner flakes or steamed for a longer period of time—or undergo both processes—in order to produce easier-to-chew oats that can be prepared at home quite quickly.
Steel cut oats are whole oat groats that have been cut into smaller pieces. Like their name implies, these oats are usually cut into pieces using a steel blade. Sometimes “steel cut” is a term for oats that is used synonymously with “Irish” or “Scottish” oats. However, a more traditional use of these terms would restrict “steel cut” to whole oat groats that have been cut with a steel blade and “Irish” or “Scottish” to whole oat groats that have been stone-ground. All oats in this general category (steel cut, Irish, Scottish) have varying cooking times depending on the size of the resulting pieces. We have seen steel cut oats that were cut into very small pieces and cook within 5-7 minutes. However, we have also seen large-pieced steel cut oats that took 20-30 minutes to cook.
Ordinarily, you might assume that quick and instant oatmeals were far less nutritious that either old-fashioned rolled oats or steel cut oats. While there are definitely some measurable differences in these different oat types, they are far more similar, rather than dissimilar, in terms of their conventional nutrient content.
For example, you will find the protein, fiber, and fat content of all three types to fall within a fairly narrow range. This similarity in conventional nutrients is largely related to the products’ similar starting point and relatively small deviation from that starting point: all of the products above begin with whole oat groats and don’t rely on removal of major groat components to produce the final version of the oats.
However, like most moderately high carbohydrate-containing foods, increased amounts of processing usually result higher glycemic index (GI) values for the food and this rule clearly applies to oats. Most of the GI values that we have seen for old-fashioned and steel cut oats fall into the range of 50–65. Unfortunately, this overall range is a little bit too large to pinpoint the GI of all old-fashioned and steel cut oats as being clearly “low” (55 or below) versus “medium” (between 55–70).
Yet, with this caveat in mind, we still think it makes overall sense to think about these two categories of oats (old-fashioned and steel cut) as low in glycemic index. By contrast, most of the GI values that we have seen for instant oats fall into the 70–80 range, and researchers usually consider GI values about 70 to be “high GI.” In summary, even though these different forms of oat products are relatively similar in terms of their conventional nutrient content, and even though all of these forms are definitely less processed than many other types of processed foods in the supermarket, there are still measurable differences between these oat versions, and in the case of instant oats versus steel cut or old-fashioned, GI value is one of those differences.
From a labeling standpoint, one confusing aspect of oats involves their description as a “whole grain” food. “Whole grain” is allowed as a labeling claim by the U.S. Food and Drug Administration (FDA) whenever a grain product contains all three natural components of the grain (germ, bran, and endosperm) in “particular proportions.” However, fluctuations in the ratio of germ-to-bran-to-endosperm are allowed by the FDA, and there is no tightly defined standard with respect to these whole grain components. For example, it is not completely clear in all cases just how the germ, bran, and endosperm wind up in the final version of a whole grain product that can legally be described as “100% whole grain” by the FDA. Since all old-fashioned rolled oats and steel cut oats—as well as most instant oats—contain substantial portions of the oat’s bran, germ, and endosperm, it is common to find each version of oats (including instant oatmeals) bearing the label of “100% whole grain.”
In addition to the forms of oats and oatmeal described above, you can find isolated components of oats—especially oat bran–as well as oat flour in many supermarkets. Muffins recipes, for example, can often be found with oat bran as a key ingredient. Oat flour can be purchased in the store or made at home in a blender from rolled or steel cut oats. While not typically used to entirely replace another flour—like wheat flour—in a recipe (due to changes in density and the resulting texture), oat flour is frequently used to replace some portion of another flour in a recipe in order to bring the unique health benefits of oats into that recipe.
Oats and the “Gluten Grains”
This area of research on oats remains somewhat controversial, even though the labeling of oat products as “gluten free” has been allowed in the U.S. (and in several other countries) for many years.
Beginning in 2007, the U.S. Food and Drug Administration (FDA) excluded oats from the list of prohibited grains in their regulations for “gluten free” labeling while also allowing all oats products to be labeled as “gluten free.” Many present-day oat products display a “gluten free” label. In addition to these labeling regulations, numerous celiac organizations currently allow limited amounts of oats in meal plans designed for persons with diagnosed celiac disease, even though a goal of these meal plans is to remain gluten-free. (Celiac disease is an especially important health condition in relationship to dietary gluten since celiac disease is an autoimmune condition in which gluten-related proteins can trigger extensive damage in the small intestine.)
You can find extensive information about gluten and grains (including oats) in the following articles on our website: What is gluten? Is gluten-free the same as wheat-free? How is wheat related to other grains? Is gluten sensitivity the same thing as wheat allergy? Can I still have an unwanted reaction to wheat or grains, even if I always choose whole grains?
The reason that oats remain somewhat controversial in research studies involves the reactions of some persons diagnosed with celiac disease to some of types of proteins (prolamins) or fragments of those proteins (polypeptides from prolamins) present in oats. These reactions seem restricted to certain varieties of oats, and they have not been shown to be present in all persons diagnosed with celiac disease. However, it is easy to understand how persons faced with a diagnosis of celiac disease might want to avoid consumption of oats until the exact nature of these oat reactions was better understood. Although we do not try and address the nutrient needs or dietary guidelines of any person diagnosed with a medical conditions on our website, it would still be our recommendation that any person diagnosed with celiac disease consult with his or her healthcare provider before making a decision about inclusion of oats in a meal plan.
Nutritional Profile
Oats are an excellent source of manganese and molybdenum. They are also a very good source of phosphorus as well as a good source of copper, biotin, vitamin B1, magnesium, dietary fiber, chromium, zinc and protein. In the phytonutrient category, oats provide valuable amounts of beta-glucans and saponins (including avenacoside A,1 and avenacoside B,2).
According to the National Health and Nutrition Examination Survey from 2009-2010, consumption of oatmeal accounts for about 20% of all whole grains consumed by U.S. adults! This percentage was virtually identical to the percentage of whole grains provided by all cold cereals combined. It was also not far behind the percentage of whole grains provided by all breads and rolls. In short, oatmeal is playing a very prominent role in intake of whole grains by adults in the U.S…
Both oats and oatmeal may provide us with special digestive benefits, partly in connection with their ability to increase the viscosity of our digestive tract contents. “Viscosity” refers to the thickness of the contents and their likelihood of flowing either too quickly or too slowly through our digestive tract. Too little viscosity means too quick of a flow. And along with too quick of a flow comes increased potential difficulty with blood sugar regulation. For this reason, it is very helpful for our foods to provide us with substantial viscosity so that these foods can pass through the upper part of our GI tract (and especially our small intestine) in a healthy way. Intake of oats and oatmeal has been associated with optimal levels of viscosity in which it becomes easier for food to pass through our upper digestive tract and improve our blood sugar regulation.
Healthy passage of oats through our digestive tract has also been linked to an improved sense of fullness when we eat this popular grain. In several studies, consumption of oatmeal has been associated with an increased feeling of fullness after being consumed, and the viscosity of the oatmeal seems to be important for this feeling to occur. Also important in this process may be a unique carbohydrate (called beta-glucan) that is present in oatmeal. In one recent study, oatmeal breakfasts (consisting of approximately ½ cup of dry oatmeal in 1 cup of water and microwaved for 2 minutes) were found to result in an improved sense of fullness (as well as a decreased desire to eat) at both one and two hours following the breakfast meal.
Smaller waist circumference, lower body mass index (BMI), and decreased risk of metabolic syndrome in adults have all been associated with oatmeal intake in recent studies. All of these measurements are associated with lower risk of health problems, including risk of obesity. As a general rule, the volume of oatmeal in these encouraging studies has been approximately 1 cup cooked, with an average fiber content of 4-5 grams. We mention the fiber content of oatmeal in this context because oat fiber has been shown to play a role in these health benefits. Also notable in this context are two unique nutrients found in oats: (1) beta-glucans, which are polysaccharide carbohydrates, and (2) steroidal saponins (including avenacoside A,1 and avenacoside B,2), which are sugar-related (glycoside) molecules found mostly in the bran portion of the oats.
Beta-glucans (mentioned above) have become a special area of research focus in the relationship between oat intake and improved blood sugar regulation. While some foods that we eat can cause abrupt increases in our blood sugar level following their consumption, the beta-glucans found in oats help prevent these abrupt increases when we eat oats. Specifically, between 3-6 grams of beta-glucans per serving of oats seem necessary to provide this moderating effect on our blood sugar level. We have seen one recent meta-analysis of six studies in this area (“meta-analysis” means that the results of multiple studies were statistically combined together in order to produce a more powerful statistical analysis) that showed lower levels of hemoglobin A1C (a blood test often used to assess blood sugar control over a three-month period) following daily consumption of approximately 1 cup cooked oatmeal at breakfast.
When taken as a group, the above studies on oats and oatmeal were one important factor in our decision to include oatmeal in the majority of breakfasts in our WHFoods 7-Day Meal Plan.
Health Benefits
Oat’s Digestive Support
Once foods are eaten, not all of them have an equally supportive impact on our digestive tract. For example, when eaten in large amounts, food with disproportional amounts of fat can slow down our digestive process excessively, including the rate of that foods pass out of our stomach (known as the rate of emptying). Foods that contain disproportional amounts of simple sugars and simple starches can work in the opposite direction, speeding up the digestive process and challenging our blood sugar regulation. By contrast, oats are a food that seems to provide us with unusually helpful digestive support.
A key focus in studies on oats and digestive support has been the unique fibers known as beta-glucans. Water-soluble fibers, beta-glucans support our digestion in two basic ways.
First, beta-glucans increase the “viscosity” of our food contents when they are present in our upper digestive tract. While “viscosity” is a measurement that generally refers to thickness, the idea of viscosity actually involves more than just thickness. When a substance is “viscous” it is not only thick but it is also resistant to flow. Honey and molasses are examples of viscous fluids that take time to pour out of a bottle or jar. Compared to non-viscous fluids like water, these viscous fluids take much longer to pour out and be emptied from the container in which they reside. The beta-glucans in oats appear to have this same type of effect in our small intestine. They allow our food to keep moving through our digestive tract, but they also help regulate the pace by slowing it down and allowing more time for nutrient digestion and absorption.
The increased viscosity of our GI contents may also be accompanied by more engagement of the smooth muscles that surround our small intestine, as well as by the release of digestion-related hormones. This hormone release may include peptide YY and glucagon-like peptide-1 (GLF-1), which are associated with increased feelings of fullness and satisfaction with food. So as you can see, there are a variety of factors that fall into this “digestive support” category when oats are present in the upper portion of our GI tract.
The digestive tract support provided by oats extends to our lower GI tract as well. In our large intestine (colon), oats—including their beta-glucans—get fermented by intestinal bacteria. This fermentability of oat fibers like beta-glucans not only helps maintain healthy bacterial populations in our large intestine, but it also provides the release of short chain fatty acids from these fibers that can provide energy for our intestinal cells.
Researchers have linked both aspects of digestive tract support—increased viscosity in the small intestine and fermentability in the large intestine—to better regulation of insulin, blood sugar, and cholesterol. While these health benefits have sometimes been associated with particular amounts of beta-glucan in oats, there remains a good bit of debate about the exact amount of beta-glucan that is needed. Most studies suggest that 1-2 grams of beta-glucan per serving of oats is not sufficient to provide optimal benefits, and that a more desirable range for beta-glucan intake falls between 3-6 grams per serving. Unfortunately, however, more research is needed before a firm conclusion can be reached about these beta-glucan amounts. More research is also needed about specific varieties of oats and variations in beta-glucan content. Still, the overall research is very clear about the digestive support provided by this unique grain.
Blood Sugar Support Provided by Oats
Although mentioned earlier in this profile, it’s worth singling out blood sugar support as a special health benefit provided by oats. Of course, healthy regulation of blood sugar would be expected from most any whole food that provided us with a substantial amount of protein and fiber. Both of these macronutrients can be helpful in stabilizing our blood sugar because both help moderate the passage of food through our GI tract and engage our digestive processes in a balanced way. Interestingly, you will not find oats in our Top 25 WHFoods for either protein or fiber; therefore, they are not an especially concentrated source of either macronutrient. Yet, they are a significant and balanced source, with ¼ cup of dry unprocessed oats typically providing us with 6-7 grams of protein and 4-5 grams of fiber. Importantly, the fiber in oats is split between soluble and insoluble, providing us with digestive benefits from both fiber types. And equally important, the soluble fiber in oats includes their beta-glucans.
Researchers are not entirely clear about all of the connections that exist between oat intake and blood sugar regulation. All studies point to an important role played by the soluble fiber found in this grain and the beta-glucans that are contained within this soluble fiber component. Also involved may be minerals like manganese (oats are the number 2 source of manganese at WHFoods), the B vitamins they contain (as they play a role in glucose metabolism), and oat saponins, including avenacoside A,1 and B,2. Perhaps it is the unique combination of all these factors in oats that result in the blood sugar support seen in research studies. Intake of oats and oatmeal has repeatedly been shown to improve after-meal (postprandial) blood sugar and insulin levels. In addition, healthy levels of hemoglobin A1C have been associated with intake of both oats and oatmeal. (Hemomglobin A1C is a form of the key protein in our red blood cells—hemoglobin—in which the protein gets linked up with a sugar molecule through a process called glycosylation. If an overly high percentage of our hemoglobin proteins begin to take this form, healthcare providers begin to suspect problems in glucose and insulin metabolism. Since our red blood cells live for approximately three months, hemoglobin A1C levels are viewed as representing the degree of blood sugar stability over a three-month period. In persons at risk for blood sugar problems, intake of both oats and oatmeal have been associated with healthier levels of hemoglobin A1C—which researchers consider evidence of blood sugar support provided by the intake of this grain.
One final issue that we would like to address regarding oats and blood sugar is glycemic index (GI). Although you will find a more detailed description of this issue in the Description section of this profile, we think that it is important to point out that the GI values that we have seen for old-fashioned rolled oats and steel cut oats are significantly lower than the values that we have seen for instant oats. The overall GI range for old-fashioned rolled oats and steel cut oats is 55–70. By contrast, the overall GI range for instant appears to be much closer to 70–80. At WHFoods, we treat 55 or below as “low GI;” 56–69 as “medium GI;” and 70 or above as “high GI.” So you can see that old-fashioned rolled oats and steel cut oats fall into the low or medium GI range, while instant oats fall into the high range. For this reason, old-fashioned or steel cut oats (versus instant oats) would be expected to provide you with better blood sugar support than instant oats.
Oats’ Cardiovascular Support
Strong intake of fiber—including both soluble and insoluble fiber—has long been associated with decreased risk of cardiovascular problems. While the focus in many cardiovascular studies has remained on soluble fiber, research has shown cardiovascular benefits for both fiber types. Soluble fiber—just like its name suggests—is especially “friendly” toward water. Soluble fibers can take on water, swell, and hold water. This characteristic of soluble fiber can lead to improved viscosity in our small intestine contents as described earlier in this profile. As a result of this improved viscosity, we get improved digestion and absorption of nutrients, including some of the key cardiovascular-support nutrients present in oats. These nutrients include multiple B vitamins, as well as the minerals magnesium and zinc. Within the soluble fiber portion of oats are found beta-glucans, and intake of these unique polysaccharide fibers has been associated with decreased levels of total and LDL cholesterol.
In a very large scale study in Denmark involving over 50,000 adults between the ages of 50–64 years, intake of oats has been associated with decreased risk of heart attack (also known as myocardial infarct, or MI). Researchers conducting this study pointed to potential roles for both soluble and insoluble fibers in producing the study results. Some more complicated metabolic processes may also be involved in the cardiovascular benefits related to intake of oats. In particular, researchers have been interested in the ability of oat intake to lessen the risk of excessive inflammation in the blood vessels. The series of events in this area of research has sometimes focused on some unique phenolic, nitrogen-containing molecules in oats called avenathramides. Also of interest have been the oat saponins—primarily avenacoside A,1 and avenacoside B,2. These sugar-related (glycoside) molecules are found primarily in the bran portion of the oat, and like beta-glucan, their intake has been associated with decreased levels of LDL and total cholesterol.
It’s important not to lose the forest through the trees, however, when looking at the cardiovascular benefits of oats and oatmeal. In multiple studies, consumption of this grain has been associated with decreased risk of metabolic syndrome, decreased risk of obesity, lower waist circumference, and lower body mass index (BMI). These findings all point in the direction of cardiovascular support following routine intake of this unique grain. Also worth mentioning in this context are the findings from an analysis of the data from the Nutrition Health and Examination Surveys (NHANES) between 2001—2010 in the U.S. In these analyses, children who ate oatmeal on a regular basis were found to have decreased risk of “central adiposity”, which is the accumulation of excessive body fat in the general abdominal area.
Description
Oats are a member of the grass family of plants (Poaceae) and are often described as a “cereal grass” or “cereal grain.” In this context, the word “grain” refers to the edible seeds of the plant and the word “cereal” refers to the practice of growing these plants in order to obtain their grains. In other words, oats are correctly described as a cereal grain because they are typically grown for their grain (seeds), and they are also correctly described as a “cereal grass” because in addition to being cultivated for their grain/seed content, they also belong to the grass family of plants (Poaceae).
Unlike oats, however, some plants referred to as “cereal grains” do not belong to the grass family. These non-grass grains are sometimes called “pseudograins” or “pseudocereals.” The “pseudograins” or “pseudocereal grains” include buckwheat, amaranth, quinoa, and teff. The cereal grasses include not only oats but also wheat, rye, barley, kamut, spelt, triticale, sorghum, rice, corn (maize), and millet. In its labeling standards, however, the U.S. Food and Drug Administration (FDA) does not differentiate between the cereal grains versus the pseudocereal grains, imply including all of the plants listed above as cereal grains.
In addition to being members of the grass family, oats belong to the science genus/species Avena sativa.
Virtually all oats available in supermarkets have been processed to varying degrees. Minimal oat processing usually includes cleaning (including both screening and air blowing, or aspiration) and hulling. Screening and aspiration are used to remove weed seeds, non-oat grains, and loose (unattached) hulls from the oats. Hulling is used to remove hulls that are still naturally attached to the oats at the time of harvest. (These oat hulls can also be referred to as “chaff.” Once the oats have been cleaned and hulled, they are usually referred to as “whole oat groats” or simply “groats.”) After the cleaning and hulling the oat grains in order to produce the groats, additional processing steps may take place in production of the final oat products.
In the U.S., three types of oat products dominate the marketplace: (1) “old-fashioned” or “regular” rolled oats, (2) quick and instant rolled oats, and (3) steel cut oats. “Old-fashioned” rolled oats usually consist of whole oat groats that have been steamed and rolled to produce their somewhat irregular but recognizably flat and disc-like shape. After rolling, old-fashioned oats are heat-dried to reduce moisture.
Quick and instant rolled oats typically vary from old-fashioned rolled oats in at least one of two ways. They are either rolled into thinner flakes or steamed for a longer period of time—or undergo both processes—in order to produce easier-to-chew oats that can be prepared at home quite quickly.
Steel cut oats are whole oat groats that have been cut into smaller pieces. Like their name implies, these oats are usually cut into pieces using a steel blade. Sometimes “steel cut” is a term for oats that is used synonymously with “Irish” or “Scottish” oats. However, a more traditional use of these terms would restrict “steel cut” to whole oat groats that have been cut with a steel blade and “Irish” or “Scottish” to whole oat groats that have been stone-ground. All oats in this general category (steel cut, Irish, Scottish) have varying cooking times depending on the size of the resulting pieces. We have seen steel cut oats that were cut into very small pieces and cook within 5-7 minutes. However, we have also seen large-pieced steel cut oats that took 20-30 minutes to cook.
Ordinarily, you might assume that quick and instant oatmeals were far less nutritious that either old-fashioned rolled oats or steel cut oats. While there are definitely some measurable differences in these different oat types, they are far more similar, rather than dissimilar, in terms of their conventional nutrient content.
For example, you will find the protein, fiber, and fat content of all three types to fall within a fairly narrow range. This similarity in conventional nutrients is largely related to the products’ similar starting point and relatively small deviation from that starting point: all of the products above begin with whole oat groats and don’t rely on removal of major groat components to produce the final version of the oats.
However, like most moderately high carbohydrate-containing foods, increased amounts of processing usually result higher glycemic index (GI) values for the food and this rule clearly applies to oats. Most of the GI values that we have seen for old-fashioned and steel cut oats fall into the range of 50–65. Unfortunately, this overall range is a little bit too large to pinpoint the GI of all old-fashioned and steel cut oats as being clearly “low” (55 or below) versus “medium” (between 55–70).
Yet, with this caveat in mind, we still think it makes overall sense to think about these two categories of oats (old-fashioned and steel cut) as low in glycemic index. By contrast, most of the GI values that we have seen for instant oats fall into the 70–80 range, and researchers usually consider GI values about 70 to be “high GI.” In summary, even though these different forms of oat products are relatively similar in terms of their conventional nutrient content, and even though all of these forms are definitely less processed than many other types of processed foods in the supermarket, there are still measurable differences between these oat versions, and in the case of instant oats versus steel cut or old-fashioned, GI value is one of those differences.
From a labeling standpoint, one confusing aspect of oats involves their description as a “whole grain” food. “Whole grain” is allowed as a labeling claim by the U.S. Food and Drug Administration (FDA) whenever a grain product contains all three natural components of the grain (germ, bran, and endosperm) in “particular proportions.” However, fluctuations in the ratio of germ-to-bran-to-endosperm are allowed by the FDA, and there is no tightly defined standard with respect to these whole grain components. For example, it is not completely clear in all cases just how the germ, bran, and endosperm wind up in the final version of a whole grain product that can legally be described as “100% whole grain” by the FDA. Since all old-fashioned rolled oats and steel cut oats—as well as most instant oats—contain substantial portions of the oat’s bran, germ, and endosperm, it is common to find each version of oats (including instant oatmeals) bearing the label of “100% whole grain.”
In addition to the forms of oats and oatmeal described above, you can find isolated components of oats—especially oat bran–as well as oat flour in many supermarkets. Muffins recipes, for example, can often be found with oat bran as a key ingredient. Oat flour can be purchased in the store or made at home in a blender from rolled or steel cut oats. While not typically used to entirely replace another flour—like wheat flour—in a recipe (due to changes in density and the resulting texture), oat flour is frequently used to replace some portion of another flour in a recipe in order to bring the unique health benefits of oats into that recipe.
Oats and the “Gluten Grains”
This area of research on oats remains somewhat controversial, even though the labeling of oat products as “gluten free” has been allowed in the U.S. (and in several other countries) for many years.
Beginning in 2007, the U.S. Food and Drug Administration (FDA) excluded oats from the list of prohibited grains in their regulations for “gluten free” labeling while also allowing all oats products to be labeled as “gluten free.” Many present-day oat products display a “gluten free” label. In addition to these labeling regulations, numerous celiac organizations currently allow limited amounts of oats in meal plans designed for persons with diagnosed celiac disease, even though a goal of these meal plans is to remain gluten-free. (Celiac disease is an especially important health condition in relationship to dietary gluten since celiac disease is an autoimmune condition in which gluten-related proteins can trigger extensive damage in the small intestine.)
You can find extensive information about gluten and grains (including oats) in the following articles on our website: What is gluten? Is gluten-free the same as wheat-free? How is wheat related to other grains? Is gluten sensitivity the same thing as wheat allergy? Can I still have an unwanted reaction to wheat or grains, even if I always choose whole grains?
The reason that oats remain somewhat controversial in research studies involves the reactions of some persons diagnosed with celiac disease to some of types of proteins (prolamins) or fragments of those proteins (polypeptides from prolamins) present in oats. These reactions seem restricted to certain varieties of oats, and they have not been shown to be present in all persons diagnosed with celiac disease. However, it is easy to understand how persons faced with a diagnosis of celiac disease might want to avoid consumption of oats until the exact nature of these oat reactions was better understood. Although we do not try and address the nutrient needs or dietary guidelines of any person diagnosed with a medical conditions on our website, it would still be our recommendation that any person diagnosed with celiac disease consult with his or her healthcare provider before making a decision about inclusion of oats in a meal plan.
Nutritional Profile
Oats are an excellent source of manganese and molybdenum. They are also a very good source of phosphorus as well as a good source of copper, biotin, vitamin B1, magnesium, dietary fiber, chromium, zinc and protein. In the phytonutrient category, oats provide valuable amounts of beta-glucans and saponins (including avenacoside A,1 and avenacoside B,2).
