Oats: uses and health benefits

In this Article (Index)

• Oats
• Health Promoting Properties
• Oats' Chemical Composition
• Oats as Food
• Rolled, Instant, and Steel Cut Oats
• Rolled Oats
• Instant Oats
• Steel Cut Oats
• Oat Milk
• Health Benefits of Oats
• Cholesterol-lowering effects and reduced risk of cardiovascular disease
• Diabetes
• Cancer-preventive effects of oats
• Constipation and Digestion
• Obesity
• Inflammatory Bowel Disease & Ulcerative Colitis
• Oats for Skin disorders
• Anti-inflammatory effects
• Celiac Disease and Oats
• Avenin
• Cross-contamination

Oats

Oats, whose scientific name is Avena sativa is an annual herbaceous plant that can grow to a height of almost 6 feet (1.8 m). They have been cultivated since prehistoric times; wild oat grains have been found in a granary in the Jordan Valley that were 11,200 to 11,400 years old. They adapted well to the cold humid climate of Europe where they were grown as a domesticated plant some 3,000 years ago.

They are cereals like barley, wheat, and rye, and come in several varieties. Oats are the sixth most cultivated cereal in the world.

Oats are consumed as whole grain, rolled, steel-cut, and as flour, bran, and non-dairy milk.

Health Promoting Properties

Oats are a source of dietary fiber like beta-glucan (β-glucan) which absorbs cholesterol in the gut, reducing the risk of cardiovascular disease; it also has antidiabetic effects. Fiber also bulks stool, promoting a rapid intestinal transit.
Oats contain bioactive compounds like polyphenols, sterols, and alkaloids that have antioxidant and anti-inflammatory properties, act upon the gut microbiota, and promote immunity. They may also have anti-cancer properties.
Oats have been used since antiquity to treat skin conditions such as dermatitis. (1),(7)

We will look into each of these health claims in the following sections.

Oats' Chemical Composition

Nutrient data for steel-cut oats from the U.S.D.A show that Oats, like all grains, contain carbohydrates in the form of starch (55%), natural 2.5% sugars, and protein (11-15%). Roughly 80% of the protein is in the form of globulins, with prolamins making up 15%, and glutelin and albumin making up the rest.

Oats have between 5 and 12% lipids (fat) content higher than other cereals. Palmitic which is a saturated fatty acid constitutes 20-25% of the total fats. 75-80% of the lipids are unsaturated fatty acids which are mostly oleic, a monounsaturated fatty acid or MUFA, and linolenic, an Omega-3 (ω-3) polyunsaturated fatty acid or PUFAs; it also contains linoleic, an Omega-6 (ω-6) PUFA.

The energy content in 100 g of steel-cut oats is 381 kcal.

Rich in Dietary Fiber

Dietary fiber, or fiber, are carbohydrates found in plants known as polysaccharides, that are bound in such a way that they cannot be digested in the small intestine, and can only be fermented by the microbes that live in the colon. Oats roughly 10% of total fiber of which half is insoluble fiber, and the other half is a type of fiber called Soluble Fiber that dissolves in water and forms a viscous gel that has cholesterol-lowering properties. You can also find it in nuts, lentils, peas, and beans. This fiber can be digested, at least in part, by the bacteria in the gut.

This soluble fiber in oats is known as βglucan, and oats contain between 2 and 5% of it.

Plant-based Chemicals (Phytochemicals)

Mainly tocols (86-91%), comprising α-tocotrienols and α-tocopherols. Vitamin E activity is contributed by tocopherols and tocotrienols, which together make tocols. (1)

Oats also contain phenolic compounds (6%), the most abundant are ferulic acid (roughly 60-80% of the total phenolics), caffeic acid, and sinapic acid. Other polyphenols are protocatechuic acid, p-hydroxy benzoic acid, vanillic acid, and p-coumaric acid. Most of these phenolic compounds are found in the bran layer of the oat grain where it is higher than in flaked and rolled oats. (1)

Among them are trace amounts of flavonoids like apigenin, glycosylvitexin, isovitexin, and tricin.

Avenanthramides or AVA are antioxidant phenolic compounds that are unique among grains. The antioxidant activity of AVAs is 10 to 30 times greater than that of other phenolic antioxidants such as vanillin and caffeic acid. Oats contain 2-4% of AVA1A, 3-6% of AVA2 and 2-5 % of AVA3. (6),(7)

Minerals and Vitamins

Oats have small amounts of trace minerals and vitamins; values per 100 g are: calcium (Ca): 51 mg, iron (Fe): 3.8 mg, phosphorus (P): 376 mg, Zinc (Zn): 2.8 mg, copper (Cu): 0.4 mg, manganese (Mn): 3.4 mg, selenium (Se): 20 μg, and Molybdenum (Mo): 164 μg.

Vitamins in oats include thiamin 0.334 mg, niacin 0.926 mg, Vitamin B6 0.119 mg, biotin 22 μg and Folate, total 30 μg.

Oats as Food

Rolled, Instant, and Steel Cut Oats

Like all cereals, oats have kernels with tough outer shells called husks that have to be removed to make them edible. The husk makes up around 15% of the grain's weight. This is done during the milling process where the grains are cleaned, graded by size and thickness, and hulled; the crushed hull is removed, leaving the edible groat for further processing.

Groats are very rich in fats, but the bran that coats them contains lipases, enzymes that can modify the fats making them rancid. The lipases are deactivated with a heat treatment using steam (212°F -100°C for 90-120 minutes). The heat also kills any bacteria or fungi that could damage the groats. Steam adds humidity to the groats softens the groats and avoids breakage during flaking. (6)

Rolled Oats

Rolled oats are made by using whole-grain groats after steaming them. Then they are toasted slightly and rolled into flat flakes (flaking) between heavy rollers.

Instant Oats

Instant oats are more processed than regular rolled oats. They have been cut into smaller pieces and rolled thinner, and they also contain added sugars and added salt as well as flavorings that may be artificial (maple syrup, cinnamon, etc.)

Steel Cut Oats

Also known as Irish oatmeal, pinhead oats, or coarse oatmeal, steel-cut oats are not rolled or steamed, instead, the groats are cut with steel blades into pinhead-sized pieces. Each groat is chopped into 2 to 3 pinheads.

They take longer to cook than regular rolled oats and have a coarser and chewier texture.

Other food uses of oats

Oats are also ground into a fine oat flour used in celiac bakery, oatmeal is a main ingredient in baked goods such as oatcakes and oatmeal cookies. Muesli, granolas, and cereal bars rely on rolled oats for texture and flavor. Oats are also used to make oat milk, a popular plant-based milk substitute.

Oat Milk

Oat milk was created by Swedish scientists in the 1990s and sold under the Oatly brand for those who sought lactose-free and low-carbon footprint milk. The original recipe combined 200 g of oats with 35 g of canola oil. The modern process mixes 1kg rolled oats with 2.7 kg of water the slurry is then mixed with enzymes that break it down, it is filtered, and solids (0.86 kg) are removed. The milk (2.85 kg). However, fat globules are needed to give plant-based milk a milky feel.

Oat milk fat globules are prepared with water, emulsifiers, additives, and oil (olive oil, corn oil, coconut oil, sunflower oil, and soybean oil).
The emulsifiers can be phospholipids, polysaccharides, and proteins, such as soy lecithin, monoglycerides, and sucrose esters. Thickeners may also be added, as well as vitamins, calcium carbonate, and minerals. (8)
Oat milk is not as natural as you think. Iit is a processed food packed with manmade ingredients.

Health Benefits of Oats

Oats have many health benefits, and several have been reviewed by the European Food Safety Authority (EFSA) which has approved the following oat health-related claims:

1. "Oat beta-glucan has been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of (coronary) heart disease". ⁽ⁱ⁾
2. "Consumption of beta-glucans from oats or barley contributes to the reduction of the glucose rise after a meal". ⁽ⁱⁱ⁾
3. "Oat grain fibre contributes to an increase in faecal bulk". ⁽ⁱⁱⁱ⁾
4. "Regular consumption of beta-glucans contributes to maintenance of normal blood cholesterol concentrations". ^(iv)

This section will summarize the health benefits of oats.

• Cholesterol-lowering effects and reduced risk of cardiovascular disease
• Diabetes
• Cancer-preventive effects of oats
• Constipation and Digestion
• Obesity
• Inflammatory Bowel Disease & Ulcerative Colitis
• Oats for Skin disorders
• Anti-inflammatory effects

Cholesterol-lowering effects and reduced risk of cardiovascular disease

The β-glucans in oats reduce cholesterol levels (claim #1 further up); claims related to oats' beta-glucans and cholesterol have been approved by food and health safety authorities in Australia and New Zealand, Canada, and Malaysia. (1)

The U.S. Food and Drug Administration (FDA) also approved cardiovascular risk reduction health claims for oat-based products if consumed at the rate of 3 g per day of beta-glucan and if each serving contains 0.75 g of beta-glucan.

Blood Pressure

By modifying the blood lipids, beta-glucan-rich oats also lower blood pressure, this effect is enhanced by the viscous fiber that slows down the absorption of nutrients and especially sugars after a meal, reducing the sugar spike and lowering the insulin response, reducing blood pressure. (1)

Heart Health

Besides the blood lipids lowering effects and anti-hypertensive action of oats, two additional factors may contribute towards a reduction in heart and cardiovascular disease: (i) the polyphenols and the avenanthramides found in oats exert an antioxidant and anti-inflammatory effect (1), and the high levels of unsaturated fatty acids found in oats. (2)

Diabetes

Oats have anti-diabetic effects; a meta-analysis using information from 8 trials with 407 patients found that consuming oat β-glucan improved HbA1C, fasting glucose, 2h-PG and HOMA-IR. The authors concluded that "consumption of oats and oat ß-glucan results in generally small improvements in established markers of fasting and postprandial glycemic control beyond concurrent therapy in adults with type 2 diabetes. The current evidence provides a very good indication for reductions in fasting glucose and less of an indication for reductions in HbA1c, 2h-PG, fasting insulin, and HOMA-IR in this population." (5)

There are several mechanisms by which oat soluble fiber acts upon diabetes: it increases the viscosity of the food bolus in the stomach slowing down its transit into the small intestine; viscosity also slows down the diffusion of glucose and its absorption. This lowers the sugar spike that follows meals (postprandial hyperglycemia), lowering insulin secretion.

Bear in mind that the effectiveness of β-glucan is influenced by the cooking time (more cooking lowers its effects), and type of oats: large flake oats and steel cut oats have a low glycemic index (GI) value, granola and muesli (depending on added sugar content) have a medium GI value, and instant oats and vegan oat milk have higher GI values. (1)

Cancer-preventive effects of oats

Fiber has been associated with a lower risk of developing colorectal cancer (9), suggesting that oats, which have a high level of both soluble and insoluble fiber, can exert cancer-preventive effects.

Oats contain unique saponins, avenacosides that exert inhibitory effects against the growth of colon cancer cells. However further research is necessary to prove its effectiveness. (10)

A systematic analysis of 38 studies, conducted in 2014(3) concluded that oats or oat bran might have preventive effects on colorectal adenoma and cancer. Yet the evidence is tenuous: "A protective effect on colorectal adenoma and cancer is plausible but it has not been convincingly shown."

Constipation and Digestion

Oats soluble and insoluble fiber content help increase stool size, and by absorbing water, its weight. This bulking effect softens stool and improves intestinal transit.
An added benefit of fiber is that it helps prevent an upset stomach by easing gastric emptying. (1)

The 2014 study mentioned above confirms that "oats or oat bran can significantly increase stool weight and decrease constipation, but there is a lack of evidence to support a specific effect of oats on bowel function compared with other cereals." (3) Suggesting that fiber whether from oats or other whole grains helps relieve constipation (learn more about fiber and constipation.)

Obesity

Studies using animals have shown that oats modify the gut microbiota promoting the growth of beneficial microbe. This has an effect on obesity, lowering it. Rats fed with an oat-supplemented diet lost weight and abdominal fat; their sugar and lipid blood levels also dropped. Studies on animal models show the effects of oats in the modulation of gut microbiota and its subsequent effect on reducing obesity. (1)

Inflammatory Bowel Disease & Ulcerative colitis

A 2014 meta-analysis identified two studies with oat bran in patients suffering from ulcerative colitis who "showed small improvements in the patients' conditions." (3) The authors concluded that "long-term dietary intake of oats or oat bran could benefit inflammatory bowel disorders, but this remains to be proven...[and] could present some benefits for patients with IBS and UC." (3).

Oats for Skin disorders

Colloidal oats have been used for hundreds of years to treat skin disorders like burns, rashes, itch, eczema, and erythema (redness).

The soothing, anti-irritation, and moisturizing properties of oats stem from the anti-inflammatory and anti-itching properties of oat AVAs (phenolic alkaloids), and beta-glucans. (1)

Anti-inflammatory effects

A meta-analysis of 23 randomized clinical trials or RCTs found that "no significant alterations were found after oat consumption" in four key inflammation markers: C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). However, eating oats did "significantly decrease CRP levels in subjects with one or more health complications [and]... IL-6 levels were significantly decreased in subjects with dyslipidemia."

This suggests that individuals with health issues could benefit more from a higher intake of oats. (4)

A similar effect was reported in a 2024 meta-analysis involving 16 RCTs: Oats and barley consumption may confer anti-inflammatory effects in metabolically at-risk populations and influence gut microbiota outcomes. However, no anti-inflammatory benefits were observed in healthy individuals." (11)

Celiac Disease and Oats

In Canada, the United States, and the European Union, oats and oat-based products can be labeled "gluten-free" if they contain less than 20 ppm (parts per million) of gluten.
However, other countries like Australia, New Zealand, and Argentina, consider that the risk of cross-contamination is too high and do not allow oats to be labeled as "gluten-free."

Avenin

Cereals like wheat, rye, and barley belong to the Triticeae family and contain gluten, while oats belong to another one, the Avenaee family.

Gluten is a complex mixture of proteins, the main ones are known as prolamins; they are the major proteins in wheat, rye, and barley, while rice and oats, have smaller amounts with glutelins and globulins being their major proteins.

The prolamin and glutamine-rich proteins like gliadin (wheat), secalin (rye), and hordein (barley) cause an immune reaction in celiac patients. These aren't found in oats.

The prolamin content in oats is 15%, and they are known as avenins and have a similar chemical structure to the prolamin proteins found in wheat, barley, and rye, but they are not identical. (1)

It is assumed that avenin does not cause the same reaction in most patients with celiac disease, and several studies have shown that uncontaminated oats have no negative effects, and that "the majority of patients with coeliac disease could consume up to 100 g/d of uncontaminated oats." (3)

A Word of Caution

Nevertheless, research has shown that some oat varieties can activate immune responses (T-cell activation) and provoke inflammation typical of celiac disease. Many clinical studies have been made using non-reactive oats which may bias their outcomes. Roughly 2 out of 15 celiac patients show damage to their gut lining after a one-year oat challenge, but whether this is due to oat protein or lack of adherence to the gluten-free diet has not yet been shown. (12)

Cross-contamination

The main risk comes from cross-contamination. Oats are usually grown near gluten-containing grains, and transported, stored, and processed in equipment used by other gluten-containing grains. Contamination levels in commercially available oats pose a health risk for celiac disease patients. Those who are very sensitive to gluten should avoid consuming oats. (1),(2)