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One Secret Side Effect of Drinking Oat Milk, Says a Dietitian

Before you sip, take an oath to know your oats.
FACT CHECKED BY Olivia Tarantino

You can call the humble oat the GOAT of grains, that is, the Greatest Of All Time, because it's so rich in healthful nutrients, so simple, and so easy to work into your daily diet. And it's gluten-free. Oats are on the "eat-this lists" of so many diets and dietitians for their ability to help people lose weight and lower their blood sugar and cholesterol. That's why you'll find it on this list of The 100 Healthiest Foods on the Planet.

But does this stellar grain live up to its reputation in the liquid form of oat milk?

Not quite.

To be sure, oat milk is a very good alternative to cow's milk or nut milks for those who are unable to drink them due to dairy or nut allergies, says Lori Zanini, RD, CDE, a registered dietitian nutritionist and certified diabetes expert in Manhattan Beach, California. It can be a terrific addition to a healthy diet as long as you choose the best kind and realize that oat milk is nutritionally different from the grain in its natural solid form. Zanini says the one negative side effect of drinking oat milk that many people may not recognize is a quick elevation in your blood sugar, something that would be a concern if you are diabetic or trying to reduce your risk of type 2 diabetes.

"When it comes to blood sugar management, it's important to realize that liquids digest much faster than foods and impact our blood sugar in a different way, much more quickly," says Zanini, who is also the author of the Diabetes Cookbook & Meal Plan for the Newly Diagnosed.

That's true even though oat milk provides some fiber. A 1-cup serving of oat milk typically contains 1 gram of beta-glucans, a type of soluble fiber. Beta-glucan "is a prebiotic that helps play a role in lowering cholesterol, but you'd get both kinds of fiber, soluble and insoluble, and much more benefit (cholesterol-lowering and blood sugar managing) by eating the actual oats versus drinking oat milk," Zanini says. (Related: What Happens to Your Heart When You Eat Oatmeal)

Carbs, Sugars, and Extras

oat milk close-up
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Oat milk is made from water and oats, but manufacturers may add other ingredients, including sunflower oil, sweeteners like cane sugar, and thickening agents. Silk Vanilla Oat Milk, for example, contains 7 grams of added sugars. Oatly! Chocolate Oatmilk has 10 grams of carbohydrates, 7 grams of which are added sugars. Even a cup of unsweetened oat milk, like Planet Oat Oatmilk, has 19 grams of carbs compared to just one gram of carbs in unsweetened almond milk like Almond Breeze.

Carbohydrates in plant milks are not exactly a bad thing, as long as you are aware that they're there, notes Zanini. "The problem is a lot of people consume foods they think are healthy but actually aren't good for our blood sugar," she says.

"Out here in California, people drink huge smoothies and order these big acai bowls and feel that they are being healthy, but all those things are really high in natural sugars. Even foods made from cauliflower often have potato starch and other things added that are detrimental to our blood sugar."

READ MORE20 "Healthy" Foods Ruining Your Weight Loss Goals

The Blood Sugar Fix

So, the bottom line is that oat milk can be fine if you drink the right kind. Blood sugar management is all about understanding your body and how food affects it, especially those foods high in natural carbs and added sugars. As a diabetes educator/nutritionist, Zanini offers a few tips that can help anyone:

  1. Know your body. Inform yourself with bloodwork. Ask your doctor to test your glycated hemoglobin, your A1c, for short. This simple blood test measures your average blood sugar levels over the past 3 months. "Ask for it at every physical. Most people don't know anything about it until it's high."
  2. Balance your plate. "You don't have to go to extremes to lower your blood sugar. You can enjoy food; just know what's in it and find a balance."
  3. Move more. "Exercise is free medicine. Add movement to your day; do anything you enjoy. It'll benefit you in amazing ways."
  4. Watch the added sugars in your beverages. Start by memorizing this list of the Unhealthiest Bottled Iced Teas. They are a significant source of calories and carbs. Choose flavored waters and seltzers, unsweetened teas, and unsweetened plant-based milks. Even oat milk in moderation.

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Jeff Csatari
Jeff Csatari is responsible for editing Galvanized Media books and magazines and for advising journalism students through the Zinczenko New Media Center at Moravian College in Bethlehem, PA. Read more
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