Question:
I’ve always eaten wholegrain oats, partly for the more solid mouthfeel, and I assumed I was getting more fibre. Harraways wholegrain oats recently disappeared from my shop, so I bought rolled oats. I was surprised to note the fibre levels were the same as those of the wholegrain. So, what are the nutritional benefits of eating wholegrain oats?
Answer:
Oats are a staple breakfast food for many good reasons. They’re budget-friendly, versatile and come packed with fibre, nutrients and bioactive compounds. But have you sacrificed any nutritional goodness by swapping from wholegrain to rolled oats?
Both wholegrain and rolled oats are made from the same raw ingredient: oat groats. They are the hulled, cleaned whole kernel of the oat grain – in other words, they are a wholegrain. The difference between wholegrain and rolled oats lies in what happens next.
To make wholegrain oats (as sold by brands such as Harraways), the dehulled groats are steamed and rolled whole, which flattens the grain while retaining its full structure. In contrast, to make rolled oats, the groats are first cut into smaller pieces (usually 2-3 segments per groat) before being steamed and rolled. This pre-cutting step means rolled oats cook more quickly and yield a softer, creamier texture.
Nutritionally speaking, both types still qualify as wholegrains. That’s because the bran, germ and endosperm are not removed in processing. So, they contain the same amount of fibre, protein, vitamins, minerals and antioxidants, which is why you noticed identical fibre values on the nutrition panels. However, because the texture is different, the mouthfeel is different, as you probably noted. Some people prefer the chewier texture of wholegrain oats, whereas others prefer the creamier version.
Interestingly, the degree to which the oats are processed does influence how our body responds to them, particularly in terms of blood sugar. When oats are cut into smaller pieces, as in rolled oats, they cook faster, but also tend to be digested more quickly. That can cause a slightly faster rise in blood glucose levels compared with larger, less-processed forms such as steel-cut and wholegrain oats. A 2015 review published in the British Journal of Nutrition found the more intact the oat grain, the slower the glycaemic response – meaning less of a blood-sugar spike after eating. So, although rolled oats are still a great option, oats that are less broken down may have a slight edge when it comes to keeping blood-sugar levels steady.
However, either type of oats offers a slower, more stable response than the many refined breakfast cereals that pack the supermarket shelves.
Where oats truly shine is in their content of beta-glucan, a soluble fibre unique to oats. This gel-forming fibre has been shown to lower LDL (bad) cholesterol, support gut health, promote bowel regularity, and help stabilise blood-glucose levels. A half-cup of New Zealand-grown rolled oats contains about 1.4g of beta-glucan, contributing substantially towards the 3g a day associated with cholesterol-lowering effects. Importantly, beta-glucan remains intact through the steaming and rolling process. So, whether your oats are wholegrain or rolled, you’re still getting those heart-health benefits.
Oats also contain a suite of valuable nutrients, including B vitamins, magnesium, iron, zinc, antioxidants and other bioactive compounds. Altogether, oats truly are a humble and nutritious option, and one that scientists now recognise not only improves blood-cholesterol levels and blood-glucose response but also our gut microbiota. The beta-glucan in oats has also been shown to enhance the body’s innate immune response, which is our first line of defence against germs, noted a 2024 review in Current Nutrition Reports.
In short, whether your oats are wholegrain or rolled, they’re nutritionally comparable. So, if your go-to product has disappeared from the shelves, you can confidently keep eating standard rolled oats, knowing you’re still getting all the fibre, nutrients and health benefits oats have to offer.
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