Oat Milk is Not a Blood Sugar Bomb

In the wild world of nutrition science myths and misinformation run rampant. Sometimes these myths have a grain of truth, which makes them challenging to dismiss. So buckle up, because throughout 2024 we will dive into some of these myths and bust them wide open with evidence.

Our journey begins with a myth about oat milk that our resident oat milk enthusiast, Lisa, stumbled upon. She showed me a battle of the milks Instagram reel by biochemist Jessie Inchauspé @glucosegoddess that claimed oat milk was just starch juice that spikes your blood sugar levels. Jessie suggested some ways to avoid this, like not drinking it on an empty stomach (who knows why?) or taking a walk after your oat milk latte.

The world of plant-based milks is confusing enough, so do we now really have to worry about a glucose spike?

Many of us choose plant-based milks to help out the planet, because of animal welfare, or we simply prefer the taste. As discussed in a previous newsletter, not all plant-based milks are equal substitutes for cow's milk, and we must be mindful of the nutrients they lack. In the case of oat milk, it has less protein than cow’s milk and you should look for ones that have added calcium and vitamin B12. And don’t forget to shake the bottle well, because calcium can settle at the bottom.

Now, let's explore whether Lisa needs to lace up her sports shoes and hit the pavement after enjoying her oat milk latte.

Firstly, a quick reminder about the glycaemic index (GI) — a system ranking carbohydrate-containing foods based on their impact on blood sugar levels. High-GI foods (70+) cause rapid glucose level fluctuations, while low-GI foods (≤55) are digested more slowly, leading to a gradual glucose release and theoretically more stable blood glucose concentrations. Moderate-GI foods (56-69) land somewhere in the middle. The system is designed to help you pick the lower GI option within a food group.

But GI is not the only factor that matters. The impact on your blood sugar also depends on the amount of carbohydrate in the food. The product of GI and carbohydrate content of a food portion is called the glycaemic load (GL).One unit of GL is equal to 1 gram of glucose. GL is also classified as low (≤10 g), moderate (11-19 g) or high (≥20 g). GL lets you compare foods that have different serving sizes.

Now, let’s look at oat milk. Most oat milks have around 6 to 7 g of carbs per 100 mL. A latte is around two-thirds milk, so a 250 mL latte has about 10 to 12 g of carbohydrate. According to the International tables of glycemic index, the GI of oat milk is 69, which means it sneaks into the moderate GI range. This means the GL of oat milk from your oat milk latte hovers around 7 to 8 — so low. Actually, it’s not much higher than the GL of an apple, which is around 5. And who ever said you need to jog off into the distance after enjoying a crisp juicy apple? (Oops, my bad—we're in nutrition territory, so there's probably someone out there with an apple jogging routine).

But getting back to oat milk, its GL is higher than cow’s milk, which is around 2 to 3. So, in theory, oat milk has more than twice the glycaemic effect of cow’s milk, but it’s still on the low side.

In practical terms, there's no need to lace up those shoes and hit the pavement after an oat milk latte.

However, it's worth noting that the GI of oat milk from the international tables is based on testing just one type of oat milk with 9 people. GI can vary a lot between people and products. A food might be low for one person, but high for another. Or even the same person may have varying responses on different days. Different ingredients and processing methods can also affect the GI of foods. For example, in the paper on the International GI tables, potatoes ranged from low (35) to high (103), depending on the variety and cooking method. Food interactions also play a role, making it challenging to reliably predict the glycaemic impact of a meal based solely on the GI of individual foods.

What does this all mean?

Oat milk has a low glycaemic load. It might raise your blood sugar more than cow’s milk, but not by much. And if you have normal glucose control, your body can handle any modest increase.

But nothing like a walk to make you feel good so lace up those shoes Lisa, and enjoy!