My husband posed this question to me yesterday morning as he was enjoying is peanut butter, chocolate, and banana overnight oats for breakfast.
I had a hunch, but I wanted to make sure I did my research first.
Short answer:
Both contain similar nutritional profiles, but soaked oats may be easier to digest and are an appetizing and efficient way to contain the beneficial resistant starch.
Long answer:
First, let's talk about why oats are nutritious in the first place.
Oats are technically a grass, which evolved ten's of millions of years ago, according to World's Healthiest Foods, but cultivation of oats began several thousand years ago. They are believed to have multiple origins including in southwestern Asia and the Mediterranean Sea (1).
Oats begin as a whole grain called a groat. To make steel cut oats, these grouts are cut up into smaller pieces with a steel blade, as the name suggests. Irish or Scottish oats are stone ground. Rolled, Regular, or Old Fashioned oats are heated by steam and flattened out, then dried to reduce moisture. Quick or instant oats either get steamed for a longer time, rolled into thinner flakes, or both.
Today, I will be talking about rolled oats as these are the type we use more often in our kitchen, and the type used more often in overnight oat recipes.
Nutrition
According to Cronometer 1/2 Cup of Regular Oats Contains:
150 Calories
Macronutrients
27 grams Total Carbohydrates (4 grams from Fiber)
5 grams of Protein
2 grams of Fat
Vitamins
16% Vitamin B1
5% Vitamin B2
3% Vitamin B3
9% Vitamin B5
3% Vitamin B6
3% Choline
3% Folate
Minerals
17% Copper
9% Iron
18% Magnesium
81% Manganese
23% Phosphorus
5% Potassium
21% Selenium
18% Zinc
Beta-Glucans
What a nutritional profile! Plus, oats are uniquely beneficial because they also contain beta-glucans, soluble fibers associated with decreased cholesterol and improving heart health (2). The also increase the viscosity of food, which slows it down. This may be why oats are so filling. Another reason they may be so filling is due to the fact that increased viscosity may increase satiety hormones peptide YY and glucagon-like peptide-1 (1).
But the benefits don't stop there! Our gut microbiota loooove beta glucans! This is ideal food for our healthy bacteria, which helps them to grow and thrive. The bacteria also ferment beta-glucans, producing short chain fatty acids, which provide energy to intestinal cells (1).
Phytic Acid
Cooked oats and soaked oats have the same nutritional profile, but the difference may be in how we digest them and how much of those nutrients we access.
Soaking is said to help break down the starch and phytic acid attached to oats, which may be positive or negative, according to this article from Precision Nutrition. In general, however, phytic acid tends to bind certain nutrients, like iron, decreasing our absorption of them. Soaking does help reduce phytic acid, but so does heat. Whether you have cooked or soaked oats, you are likely reducing this "anti-nutrient." (3,4).
Resistant Starch
The big proponent to consuming soaked oats versus cooked would be resistant starch. Resistant starch is a type of starch that is resistant to digestion and spikes in blood sugar. It is found in like green bananas and in starches that have been cooked and cooled like cold potatoes and rice. As these foods cool, the type of starch changes form.
Resistant starch is key as it holds similar benefits to fiber in that it helps feed healthy gut bacteria and produce short chain fatty acids (5). Having healthy gut bacteria is a topic for another conversation, but it is vital for overall health as it affects the brain, heart, immune system, general digestion, weight, and more.
Starches like oats, potatoes, and other grains have resistant starch, but it is destroyed during cooking and recaptured during the cooling process, according to Healthline (5). So, in soaking oats, you retain the resistant starch. However, you can also recapture it by letting a bowl of oatmeal cool after being cooked. I always eat my oatmeal cold for this reason, but not everyone will find this as appetizing as they might overnight oats, or have time to wait for their cooked oats to cool.
Conclusion
For this reason alone I would say that overnight oats are a tad bit more nutritious than cooked oats, but if you don't like overnight oats, don't sweat it! You aren't missing out on much as the nutritional profiles are highly comparable.
Interested in trying overnight oats?
V Nutrition has many overnight oat recipes, but this one is my husband's favorite
Sources
1. Oats. The World's Healthiest Foods. http://whfoods.org/genpage.php?tname=foodspice&dbid=54.
2. Goldman, Rena. Beta-Glucan: The Hear Healthy Fiber. Healthline. July 28, 2016. https://www.healthline.com/health/beta-glucan-heart-healthy.
3. 5 Reasons to Try Overnight Oats. Bob's Redmill. https://www.bobsredmill.com/blog/healthy-living/5-reasons-try-overnight-oats/.
4. Andrews, Ryan. Phytates and Phytic acid. Precision Nutrition. https://www.precisionnutrition.com/all-about-phytates-phytic-acid.
5. Mawer, Rudy. 9 Foods That Are High In Resistant Starch. Healthline. October 6, 2016. https://www.healthline.com/nutrition/9-foods-high-in-resistant-starch