Published 29th June 2023

What are the health benefits and pitfalls of eating oatmeal?

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Oatmeal is tasty and versatile. It may also benefit your health by lowering cholesterol, helping control blood sugar, and supporting gut health.

To make oatmeal, manufacturers remove oats’ outer husks and process the whole grains, or groats.

But not all oatmeal is equally healthy. Generally speaking, the more processed it is, the more quickly you’ll digest it, and the less healthy it’s likely to be.

Below, we’ll examine the science behind some possible health benefits of eating oatmeal.

1. Cholesterol levels

Oats contain a type of fiber called beta-glucan. It can help lower levels of low-density lipoprotein (LDL) cholesterol in your blood. This type is sometimes known as “bad” cholesterol. 

Having less LDL cholesterol reduces your risk of heart disease.

But exactly how much of an impact does beta-glucan have on our cholesterol levels? The results of research have varied.

One randomized controlled trial found that consuming 3 grams of beta-glucan for 8 weeks lowered LDL cholesterol levels by around 15%.

But a review of multiple studies found that a similar average dosage reduced levels by an average of just 4.2%

2. Blood sugar control

The beta-glucan in oats may also help reduce the spikes and dips in your blood sugar that can occur after you eat digestible carbs. 

In the short term, dips can lead to low energy, irritability, and increased appetite. And over time, persistently high blood sugar is linked to a greater risk of metabolic diseases, like type 2 diabetes and heart disease.

One review of multiple studies found that the beta-glucan in oats reduced blood sugar responses by 23–28%. It also lowered insulin levels. 

Another review found that blood sugar responses were healthier in participants who ate whole grains rather than highly processed breakfast oats. 

The authors suggest that an effective dose of beta-glucan was around 4 g. Half a cup (40 g) of rolled oats contains 1.5 g of beta-glucan.

3. Gut health

Oats are a good source of fiber, which can help prevent and relieve constipation

Beta-glucan is also a prebiotic — a type of fiber that helps the “good” bugs in your gut grow.

At ZOE, we run the largest nutrition science study in the world. We understand that the bacteria in your gut play a crucial role in your overall health.

Some scientists believe that a healthy, diverse community of gut bugs can help you live a longer, healthier life.

If you’re looking to improve your gut health, our personalized nutrition program can help. To learn more about how it works, take our free quiz.

4. Blood pressure

Polyphenols are a type of compound in plants, and one group of polyphenols is called avenanthramides. These are antioxidant and anti-inflammatory, and they’re unique to oats.  

Some laboratory research suggests that avenanthramides may have a positive effect on blood pressure.

One small, 4-week study had a group of participants eat daily servings of oatmeal containing high levels of these polyphenols. Two other groups ate either a combination of oats, rice, and wheat, or just rice and wheat.

The high-oat group had significant reductions in two measures of blood pressure. There were also very small increases in the widening of their arteries, though the researchers didn’t consider these to be significant.

It’s important to keep your blood pressure in the normal range because raised blood pressure is a risk factor for heart disease and other conditions.

Having a high-fiber diet is also associated with reduced blood pressure.  

5. Weight loss

Studies suggest that the fiber in oats can help you feel less hungry. This may be partly because oats slow your digestion.

However, research into whether eating oats helps with weight loss has had mixed results.

One small study found that participants who added a daily 40-g serving of oats to their usual diets for 8 weeks lost weight. In this group, certain risk factors for heart disease were also improved. 

Other research observes that while a diet with a lot of whole grains can help you control your weight, it’s unclear whether oats provide specific benefits on their own.

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Nutrition information

Oats are rich in important nutrients. They’re a source of protein, fiber, and beta-glucan. Oats also contain healthy fats, antioxidants, and a range of vitamins and minerals.

The different types of oats have similar nutrition profiles. However, the way manufacturers process them can make a big difference to how your body responds to them.

Steel-cut oats are the least processed, followed by rolled oats, then “quick oats,” which people often use to make breakfast oatmeal. 

“Instant oats” are even more highly refined. And they tend to contain added sugar, salt, and artificial ingredients.

Here are the nutrition profiles of a half-cup (40-g) serving of steel-cut and rolled oats.

Half a cup (40 g)Steel-cut oatsRolled oats
Calories152.4152.8
Protein5 g5.4 g
Fat2.3 g2.4 g
Carbohydrates27.9 g27.5 g
Fiber4.8 g4.2 g
Beta-glucan1.4 g1.5 g
Calcium20.4 mg18.4 mg
Iron1.5 mg1.7 mg
Magnesium51.6 mg50.4 mg
Phosphorous166.8 mg154.8 mg
Potassium150.4 mg140 mg
Sodium< 1 mg0.4 mg
Zinc1.1 mg1.1 mg
Copper0.2 mg0.2 mg
Manganese1.4 mg1.3 mg
Thiamin (vitamin B1)0.1 mg0.2 mg
Niacin (vitamin B3)0.4 mg0.4 mg

If you want to learn more about fiber, you can listen to the ZOE Science and Nutrition podcast on the topic.

How to make oatmeal

To make a single serving of oatmeal on the stove:

  1. Bring 1 cup of water or milk to the boil.

  2. Reduce it to a simmer.

  3. Stir in half a cup of oats and a pinch of salt (optional).

  4. Cook over a low-to-medium heat, stirring occasionally, for about 5 minutes. Less processed oats will take a bit longer.

To make oatmeal in the microwave:

  1. Mix the oats and salt with water or milk in a microwavable bowl.

  2. Cook on high for 2.5 to 3 minutes.

  3. Stir halfway through and again before serving.

Is it best to make oatmeal with milk or water?

This mostly comes down to your taste. Some people like that milk makes oatmeal creamier, while others prefer to let the natural flavor and texture of the oats come through.

The most important choice is the type of oats you use.

Things to look out for

Here are some things to keep in mind if you eat oatmeal or you’re thinking about starting: 

  • Not all oats are equal: You digest highly processed oats more quickly, and they’re more likely to lead to blood sugar spikes. So, choose steel-cut or rolled oats, which are less processed than quick oats.

  • Additives: Instant oatmeals often contain added salt, sugar, and artificial flavorings, which could counteract any health benefits. Look for products with oats as the only ingredient.

  • Traces of gluten: Oats don’t contain gluten — but manufacturers often process them alongside grains that do. If you need to avoid gluten, look for products labeled “gluten-free.”

  • Glyphosate contamination: Glyphosate is a chemical in some weed killers. Researchers have found potentially unsafe levels of it in a wide range of oatmeal products. Most of the organic products tested had much smaller amounts, so they may be safer. 

Other ways to use oats

Oats are a versatile whole grain, and there are plenty of ways to eat them beyond the standard bowl of oatmeal. Here are some ideas:

Breakfast

  • Bircher muesli: Mix oats and grated apple into plain yogurt and refrigerate it overnight. Top it with nuts and seeds in the morning.

  • Oat pancakes: Swap out flour for oats in your pancake recipe, and add yogurt to the mix to make your pancakes lighter and fluffier.

Lunch

  • Oatmeal with poached egg and sliced avocado: Add salt and pepper and a drizzle of olive oil for a savory twist on breakfast oatmeal. 

  • Oat omelet: Soak rolled oats in milk for 10 minutes, then whisk them into the eggs along with crunchy vegetables like red onion and bell pepper.

Dinner

  • Oat risotto: Use steel-cut oats instead of rice for a faster, lower-carb version. Try adding butternut squash and spinach, or leek and mushrooms.

  • Asian-style oats: Fry onions, garlic, and pak choi. Add rolled oats and a little stock. Season it with crispy chili oil and soy sauce. Serve it with salmon or smoked tofu.

Alternatives to oats

If you’re looking for healthy alternatives to oats, these grains have some of the same nutritional benefits and culinary uses:

  • Barley: This contains as much beta-glucan as oats, plus similar amounts of fiber and protein. You can use it in savory dishes like risotto.

  • Millet: This grain-like seed is gluten-free, like oats. It also contains beta-glucan, and it makes a great oatmeal substitute. You can get millet in grain form or as flakes, which are similar to oatmeal.

  • Amaranth: This is an ancient “pseudo-grain” that’s gluten free. It has a nutty flavor and is a great alternative to creamy oatmeal. Like millet, amaranth comes in grain form or as flakes.

  • Spelt: This has beta-glucan, plus more protein and almost as much fiber as oats. Its chewy texture makes spelt flour a good substitute for oats in baking. 

  • Bulgur wheat: This has a similar amount of protein to oats and even more fiber. It can work well instead of rice or couscous. 

Summary

There’s good evidence that regularly eating high-quality oatmeal could help reduce levels of “bad” cholesterol, improve blood sugar control, and support your gut health.

More processed forms of oatmeal are less healthy, and they can lead to large blood sugar rises in some people.

For variety, or if oatmeal isn’t for you, several other whole grains have similar uses in cooking and offer the same health benefits. Trying a range will add new plant foods to your diet.

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