Oats (Avena sativa) are a whole-grain cereal mainly grown in North America and Europe.

They are a very good source of fiber, especially beta glucan, and are high in vitamins, minerals, and antioxidants.

Whole oats are the only food source of avenanthramides, a unique group of antioxidants believed to protect against heart disease.

Due to their many benefits, such as lowering blood sugar and cholesterol levels, oats have gained considerable attention as a health food (1, 2, 3, 4).

They’re most commonly rolled or crushed and can be consumed as oatmeal (porridge) or used in baked goods, bread, muesli, and granola.

Whole-grain oats are called oat groats. They are most commonly rolled or crushed into flat flakes and lightly toasted to produce oatmeal.

Quick, or instant, oatmeal is made up of more thinly rolled or cut oats that absorb water much more easily and thus cook faster.

The bran, or fiber-rich outer layer of the grain, is often consumed separately as a cereal, with muesli, or in breads.

This article tells you everything you need to know about oats.

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The nutrition facts for 3.5 ounces (100 grams) of raw oats are (5):

  • Calories: 389
  • Water: 8%
  • Protein: 16.9 grams
  • Carbs: 66.3 grams
  • Sugar: 0 grams
  • Fiber: 10.6 grams
  • Fat: 6.9 grams

Carbs

Carbs make up 66% of oats by dry weight.

About 11% of the carbs is fiber, while 85% is starch. Oats are very low in sugar, with only 1% coming from sucrose.

Starch

Starch, which is comprised of long chains of glucose molecules, is the largest component of oats.

The starch in oats is different than the starch in other grains. It has a higher fat content and a higher viscosity, which is its ability to bind with water (6, 7, 8).

Three types of starches are found in oats (9, 10, 11):

  • Rapidly digested starch (7%). This type is quickly broken down and absorbed as glucose.
  • Slowly digested starch (22%). This form is broken down and absorbed more slowly.
  • Resistant starch (25%). Resistant starch functions like fiber, escaping digestion and improving gut health by feeding your friendly gut bacteria.

Fiber

Whole oats pack almost 11% fiber, and porridge contains 1.7% fiber.

The majority of the fiber in oats is soluble, mostly a fiber called beta glucan.

Oats also provide insoluble fibers, including lignin, cellulose, and hemicellulose (12).

Oats offer more soluble fiber than other grains, leading to slower digestion, increased fullness, and appetite suppression (13, 14).

Soluble oat beta glucans are unique among fibers, as they can form a gel-like solution at a relatively low concentration.

Beta glucan comprises 2.3–8.5% of raw, whole oats, mostly concentrated in the oat bran (15, 16).

Oat beta glucans are known to lower cholesterol levels and increase bile acid production. They’re also believed to reduce blood sugar and insulin levels after a carb-rich meal (17, 18, 19, 20).

Daily consumption of beta glucans has been shown to lower cholesterol, especially LDL (bad) cholesterol, and may thus decrease your risk of heart disease (21).

Protein

Oats are a good source of quality protein at 11–17% of dry weight, which is higher than most other grains (22).

The major protein in oats — at 80% of the total content — is avenalin, which isn’t found in any other grain but is similar to legume proteins.

The minor protein avenin is related to wheat gluten. However, pure oats are considered safe for most people with gluten intolerance (23, 24).

SUMMARY The carbs in oats are mostly starches and fiber. Oats pack more protein and fat than most other grains and are a good source of beta glucan, a unique, soluble fiber linked to multiple health benefits.

Oats are high in many vitamins and minerals, including:

  • Manganese. Typically found in high amounts in whole grains, this trace mineral is important for development, growth, and metabolism (25).
  • Phosphorus. This mineral is important for bone health and tissue maintenance (26).
  • Copper. An antioxidant mineral often lacking in the Western diet, copper is considered important for heart health (27).
  • Vitamin B1. Also known as thiamine, this vitamin is found in many foods, including grains, beans, nuts, and meat.
  • Iron. As a component of hemoglobin, a protein responsible for transporting oxygen in the blood, iron is absolutely essential in the human diet.
  • Selenium. This antioxidant is important for various processes in your body. Low selenium levels are associated with increased risk of premature death and impaired immune and mental function (28).
  • Magnesium. Often lacking in the diet, this mineral is important for numerous processes in your body (29).
  • Zinc. This mineral participates in many chemical reactions in your body and is important for overall health (30).
SUMMARY Oats offer high amounts of many vitamins and minerals, such as manganese, phosphorus, copper, B vitamins, iron, selenium, magnesium, and zinc.

Whole oats are rich in antioxidants that may provide various health benefits. Their main plant compounds include (3, 31, 32, 33):

  • Avenathramides. Only found in oats, avenathramides are a family of powerful antioxidants. They may reduce inflammation in your arteries and regulate blood pressure (34, 35, 36).
  • Ferulic acid. This is the most common polyphenol antioxidant in oats and other cereal grains (12, 37).
  • Phytic acid. Most abundant in the bran, phytic acid can impair your absorption of minerals, such as iron and zinc (12, 38).
SUMMARY Oats are the only dietary source of powerful antioxidants called avenathramides. They also contain ferulic acid and phytic acid.

Experts attribute oats with a wide variety of health benefits, including lower blood pressure and reduced risk of obesity and type 2 diabetes. This grain’s main benefits are listed below (39, 40, 41, 42, 43).

Can lower cholesterol

Studies have repeatedly confirmed that oats can lower cholesterol levels, which may reduce your risk of heart disease (44, 45, 46, 47).

Heart disease is the leading cause of death worldwide, and high cholesterol is a major risk factor — especially oxidized LDL (bad) cholesterol (48, 49).

Oats’ ability to lower cholesterol is mainly attributed to their beta glucan content (50, 51, 52, 53, 54).

Beta glucan may slow your absorption of fats and cholesterol by increasing the viscosity of the food you’ve eaten (55).

Once in your gut, it binds to cholesterol-rich bile acids, which your liver produces to aid digestion. Beta glucan then carries these acids down your digestive tract and eventually out of your body.

Normally, bile acids are reabsorbed into your digestive system, but beta glucan inhibits this process, leading to reduced cholesterol levels (56).

Authorities have determined that foods containing at least 3 grams of beta glucan per day may lower your risk of heart disease (57).

May prevent type 2 diabetes

Type 2 diabetes has become much more common in recent years.

This disease is characterized by the abnormal regulation of blood sugar, usually as a result of decreased sensitivity to the hormone insulin.

Beta glucans, the soluble fibers from oats, have demonstrated benefits for blood sugar control (58, 59).

Modest amounts of beta glucans from oats have been found to moderate both glucose and insulin responses after carb-rich meals (60, 61, 62).

In people with type 2 diabetes and severe insulin resistance, a 4-week dietary intervention with oatmeal resulted in a 40% reduction in the insulin dosage needed for stabilizing blood sugar levels (63).

Studies suggest that beta glucans may improve insulin sensitivity, delaying or preventing the onset of type 2 diabetes, but a review study concluded that the evidence is inconsistent (53, 64, 65, 66, 67).

Boiled whole oats cause low glucose and insulin responses, but the responses increase significantly if the oats are ground into flour before cooking (68, 69, 70).

May boost fullness

Fullness plays an important role in energy balance, as it stops you from eating until hunger returns (71).

Altered fullness signaling is associated with obesity and type 2 diabetes (72, 73).

In a study ranking the fullness effect of 38 common foods, oatmeal ranked third overall and first among breakfast foods (74).

Water-soluble fibers, such as beta glucans, may increase fullness by delaying stomach emptying and promoting the release of fullness hormones (75, 7, 76).

Human studies reveal that oatmeal may boost fullness and reduce appetite more than ready-to-eat breakfast cereals and other types of dietary fiber (13, 14, 77, 78).

Plus, oats are low in calories and high in fiber and other healthy nutrients, making them an excellent addition to an effective weight loss diet.

Largely gluten-free

A gluten-free diet is the only solution for individuals who suffer from celiac disease, as well as for many individuals with gluten sensitivity.

Oats are not glutenous but contain a similar type of protein called avenin.

Clinical studies indicate that moderate or even large amounts of pure oats can be tolerated by most people with celiac disease (79, 80, 81, 82, 83, 84).

Oats have been shown to enhance the nutritional value of gluten-free diets, increasing both mineral and fiber intakes (85, 86).

However, oats may be contaminated with wheat because they’re often processed in the same facilities (87, 88).

Therefore, it is important for people with celiac disease to only eat oats that have been certified gluten-free.

Other health benefits

Oats have a few other potential benefits.

Feeding oats to young infants under six months of age is associated with a decreased risk of childhood asthma (89).

Additionally, a few studies indicate that oats may boost your immune system, enhancing your ability to fight bacteria, viruses, fungi, and parasites (90).

In older adults, eating oat bran fiber may improve overall well-being and decrease the need for laxatives (91, 92, 93).

SUMMARY Oats offer a number of potential benefits, including reduced cholesterol and blood sugar levels. What’s more, they’re very filling and naturally gluten-free — but may be contaminated with glutenous grains.

Oats are usually well tolerated, with no adverse effects in healthy individuals.

However, people sensitive to avenin may experience adverse symptoms, similar to those of gluten intolerance, and should exclude oats from their diet (94, 95, 96).

Also, oats may be contaminated with other grains, such as wheat, making them unsuitable for people with celiac disease or a wheat allergy (87, 88).

Individuals allergic or intolerant to wheat or other grains should only buy oats certified as pure.

SUMMARY Oats are usually well tolerated but may be contaminated with gluten. Individuals who are sensitive to gluten should only consume pure, non-contaminated oats.

Oats are among the world's healthiest grains and a good source of many vitamins, minerals, and unique plant compounds.

Beta glucans, a type of soluble fiber in this grain, provide numerous health benefits. These include lower cholesterol, better heart health, and reduced blood sugar and insulin responses.

In addition, oats are very filling and may reduce appetite and help you eat fewer calories.

If you’re curious about them, you can add oats to your diet today.