Is Oatmeal Good or Bad for You? It Depends.

bowl of oatmealThough I was (and still mostly am) content to toss grains on the “do not eat” pile, I think we’re better served by more nuanced positions regarding grains. Not everyone can avoid all grains at all times, and not everyone wants to avoid all grains at all times. For those situations, it makes sense to have a game plan, a way to “rank” different grains. The reality is that grains exist on a spectrum of suitability, from wheat (avoid) to rice (fine if you need the glucose). What about oatmeal? Where do oats rank?

Today, we’ll go over the various forms of oats and oatmeal, along with any potential nutritional upsides or downsides.


First: What Is an Oat?

The common oat is a cereal grain, the seed of a species of grass called Avena sativa. Its ancient ancestor, Avena sterilis, was native to the Fertile Crescent in the Near East, but domesticated oats do best in cool, moist climates like regions of Europe and the United States. They first appeared in Swiss caves dated to the Bronze Age, Germanic tribes ate them extensively, and they remain a staple food crop in Scotland and Ireland.

Types of Oats

There are eight forms of oats that are typically available for purchase:

  • Whole Oat Groats. The “whole grain” form of an oat is called a groat and is rarely sold as-is, except maybe as horse feed or in bird seed mixes. Instead, they’re sold either as steel-cut, rolled, or instant oats.
  • Scottish Oats. These are stone ground, which are thought to make a creamier oatmeal than steel cut.
  • Steel Cut, or Irish Oats. Steel cut oats are, as the name suggests, cut into a few pieces per grain with a steel blade. These retain the most nutrients (and antinutrients like phytic acid) and taste nuttier and chewier than old-fashioned oats, quick oats, or instant oats. They take much longer to cook.
  • Old-fashioned Oats, or Rolled Oats. Rolled oats are steamed and then rolled into flat flakes.
  • Quick Oats. Quick oats are rolled thinner than old-fashioned oats for quicker cooking.
  • Instant Oats. Instant oats are rolled even thinner than quick oats, so they can be cooked with only hot water.
  • Sprouted Oats. Oats that have been germinated, or sprouted. This reduces anti-nutrient content and increases nutrient content and availability.
  • Oat flour. Oat flour starts with the whole oat groat and is ground into a fine powder.

Is Oatmeal Bad For You?

There are several potential issues with oatmeal:

  • Phytic acid
  • Avenin
  • Carbs

Phytic Acid

Phytic acid, aka IP6, is the plant storage form of phosphorus. Phytic acid binds minerals like calcium, zinc, and magnesium and prevents their absorption. Animals like rats that produce phytase (the enzyme that breaks down phytate) can thrive on phytate-rich foods like grains and seeds. But animals like humans who don’t produce much phytase can end up deficient in crucial minerals when they eat grain-heavy diets—unless they employ traditional processing methods like sprouting, soaking, and fermentation that reduce phytate content and increase mineral bioavailability. In fact, a study found that degrading the phytic acid in oatmeal improves iron absorption in human volunteers.1

While too much phytic acid in the diet can lead to deficiencies problematic, there may be positives as well:

  • Phytic acid can inhibit calcium crystals and reduce kidney stone development.4
  • If you have hemachromatosis (a tendency to absorb too much iron), you actually want to reduce your iron absorption, and dietary phytic acid can (famously) do just that.5 It’s also one of the only iron chelators that does not induce lipid peroxidation or the formation of reactive oxygen species.6
  • Phytate may also be an effective anti-cancer agent with the curious tendency to ignore the healthy cells and focus only on the cancerous ones.7

As far as amounts go, oats contain less phytic acid than corn and brown rice but about the same amount as wheat.


Avenin appears to have some of the same problems as gluten in certain sensitive individuals, although it doesn’t appear as if the problem is widespread or as serious. Kids with celiac disease produced oat avenin antibodies at a higher rate than kids without celiac, but neither group was on a gluten-free diet.2 When you put celiacs on a gluten-free diet, they don’t appear to show higher levels of avenin antibodies.3

It looks like once you remove gluten, avenin becomes far less dangerous. One study did find that some celiacs “failed” an oats challenge. Celiac patients ate certified gluten-free oats, and several showed signs of intestinal permeability, with one patient suffering all-out villous atrophy, or breakdown of the intestinal villi. A few out of nineteen patients doesn’t sound too bad, but it shows that there’s a potential for cross-reactivity.


Now, carbs aren’t “bad.” But they can be a poor choice for a type 2 diabetic or someone trying to get into and stay in ketosis. The suitability of the carbs in oats is entirely contextual: it depends on your metabolic health, your goals, your physical activity levels, your age.

The more active you are, the more carbs you can accommodate.

The more glycogen you burn, the more glycogen you can store.

The younger you are, the more carbs you can probably handle (in fact, glucose can be helpful for children who are actually growing in stature).

The more insulin resistant you are, the fewer carbs you can handle.

The more overweight you are, the fewer carbs you should consume.

It all depends.

Do Oats Contain Gluten?

Oats are often cross-contaminated with gluten because they often grow close to one another in the fields, and seeds don’t always stay where you put them. Certified gluten-free oats are not processed in the same facility as gluten grains, and they are grown far away from wheat fields.

So, if you have celiac disease and you are going to experiment with oats, make sure they’re certified gluten-free. But for everyone else, oats are going to be effectively gluten-free.

Recipe to try: Noatmeal with Blueberries and Collagen

How to Reduce Antinutrients in Oats

Some say soaking is sufficient for removing a portion of the antinutrients in oats. Others say you need lactic acid fermentation to neutralize the antinutrients. What’s the reality?


Soaking involves soaking the oats overnight in water with a tablespoon or so of acid, either from lemon juice or from apple cider vinegar. This has been shown to reduce phytic acid in other grains like brown rice, but I haven’t seen any solid literature that it does so in oats. However, I wouldn’t be surprised if it helps.

Lactic Acid Fermentation

As I understand it, you can further reduce antinutrients by lactic acid fermentation. I’m not sure the degree to which phytate can be deactivated, but one study does show that consuming oats that underwent lactic fermentation resulted in increased iron absorption.

Other sources claim that simple soaking isn’t enough, since oats contain no phytase, which breaks down phytate. Instead, you’d have to incorporate a phytase-containing flour to do the work; a couple tablespoons of buckwheat appear to be an effective choice for that. Combining both lactic acid bacteria (whey, kefir, or yogurt), companion flour (buckwheat), water, and a warm room should take care of most of the phytate… but that’s a lot of work!

Cooking Them

Simply cooking oatmeal until soft and digestible will reduce anti-nutrient content to a significant degree.


In the moist, foggy, dew-filled British Isles, traditional oat harvesting methods usually led to germination of the grain as it lay in storage. All oats were thus sprouted oats, which have been shown to have higher levels of magnesium, higher levels of GABA (which reduces blood pressure), and lower levels of phytic acid.456

If you want to sprout your own oats, you have to start with raw whole oat groats, soak them for 6 hours, drain them, and then rinse them 2-3 times a day for several days until they start to sprout. It’s an onerous process. I recommend buying them pre-sprouted. These appear to be a good brand.

Do Oats Contain Gluten?

Oats are often cross-contaminated with gluten because they often grow close to one another in the fields, and seeds don’t always stay where you put them. Certified gluten-free oats are not processed in the same facility as gluten grains, and they are grown far away from wheat fields.

So, if you have celiac disease and you are going to experiment with oats, make sure they’re certified gluten-free.

Is Oatmeal Good For You?

Oats also appear to have a decent nutrient profile, although one wonders how bioavailable those minerals are without proper processing.

A 100 gram serving of uncooked oats contains:

  • 389 calories
  • 16.9 grams protein
  • 66 grams carbohydrate
  • 10.6 grams fiber (with just under half soluble)
  • 7 grams fat (about half PUFA and half MUFA)
  • 4.72 mg iron
  • 177 mg magnesium
  • 3.97 mg zinc
  • 0.6 mg copper
  • 4.9 mg manganese

That’s uncooked. When you add liquid, heat, and time, those oats expand so you end up eating less than the full dry dose. So when you actually eat the oats, the carb count will drop but so will the nutrient concentration.

That’s unaltered. If you don’t take any steps to reduce phytic acid content, you won’t absorb as much of the iron, magnesium, and zinc as indicated by absolute amounts.

Oat Beta-Glucan

Oats contain a specific type of soluble fiber called beta-glucan that increases bile acid excretion.7 As bile acid is excreted, so too is any serum cholesterol that’s bound up in the bile.8 (That’s the idea behind the bean protocol, which we covered earlier.) The effect is a potential reduction in serum cholesterol.

In rats with a genetic defect in the LDL receptor gene—their ability to clear LDL from the blood is severely hampered—there’s some evidence that oat bran is protective against atherosclerosis.9 Of course, the very same type of LDL-receptor-defective mice get similar protection from a diet high in yellow and green vegetables, so it’s not as if oat bran is a magical substance.10 In humans, oat beta-glucan does appear to lower LDL and ApoB (a marker for LDL particle number), which may be a sign of improved heart health.11

Like other prebiotic fibers, oat bran also increases butyrate production (in pigs, at least), which is a beneficial short-chain fatty acid produced by fermentation of fibers by gut flora with a host of nice effects.12 Overall, I think these studies show that soluble fiber that comes in food form is a good thing to have, but I’m not sure they show that said fiber needs to come from oats.

How to Make Oatmeal Good For You

Okay, assuming you have your heart set on eating oatmeal, here’s how to make it more nutritious.

Cook the oats in milk: This will increase protein, calcium, and micronutrient concentration and also lower the blood glucose response.

Add micronutrients to the cooking liquid: You can sprinkle in some magnesium powder, a little vitamin K2, maybe a dash of iodine.

Add a protein source to the oats as they finish cooking: Add and stir in an egg or two toward the end to boost protein and choline content. Sprinkle in some whey protein or collagen peptides at the end.

Use sprouted oats: As described earlier, sprouted oats have more bioavailable nutrients.

All these options will make oats more nutrient-dense and “complete.”

My opinion of oats as a food? Better than wheat, worse (and more work to improve) than rice. I won’t be eating them because I frankly don’t enjoy them, there are numerous other food options that are superior to oats, and I don’t dig the weird headspace they gave me, but I’ll admit that they aren’t as bad as wheat. And if you get sprouted oats, you’ll be getting a more nutritious version of the classic oat. If I want starch, I’ll go for some sweet potatoes.

What about you folks? Do you eat oats? Would you be willing to soak, ferment, and cook them? Let me know how it works, or worked, out for you!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending more than three decades educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates flavorful and delicious kitchen staples crafted with premium ingredients like avocado oil. With over 70 condiments, sauces, oils, and dressings in their lineup, Primal Kitchen makes it easy to prep mouthwatering meals that fit into your lifestyle.

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