A seriously neglected whole grain product! It can be eaten after brewing, rich in nutrition and slow in raising blood sugar

Oats are the big star among whole grains. Many people start eating whole grains by making a bowl of oatmeal porridge for breakfast.

Instant oats do have a lot of advantages. They can be eaten as soon as they are brewed, saving time and energy while providing the rich nutrition of whole grains. However, they are easily digested and absorbed by the stomach, which also means that the glycemic index (GI) is high, even catching up with rice.

What is a high glycemic index (GI)? That is, after eating oats, blood sugar levels rise rapidly, making people prone to drowsiness, and as blood sugar levels drop rapidly, hunger is more likely to come.

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So, is there any option that can retain the advantages of oats (convenient preparation, whole grain nutrition) while improving its disadvantages (low glycemic index)?

Of course there is! Oat bran is a perfect, but often overlooked, choice.

High-quality nutrition in oats: beta-glucan

One of the reasons why oats are considered a nutritional supplement is because they are rich in beta-glucan.

Simply put, β-glucan is a highly viscous, soluble dietary fiber. Eating a moderate amount of β-glucan in oats can improve insulin resistance and dyslipidemia, and prevent hypertension and obesity . These effects have been confirmed by relevant clinical studies [1].

1.Effect: regulating blood lipids

An analysis of 58 RCTs (randomized controlled trials) covering populations in the United States, Canada, China, and other countries found that daily intake of more than 3.5 g of β-glucan for more than three weeks can significantly reduce the level of "bad cholesterol" (LDL-C) in the body [2].

2. Effect: Regulate blood sugar

A total of 103 controlled trials involving 538 subjects found that the addition of oat bran and its concentrate to a high-sugar diet could effectively suppress the blood sugar response after a high-sugar meal, with the area under the glucose curve decreasing by 23% and the peak value decreasing by 28%, while the area under the insulin curve decreasing by 22% and the peak value decreasing by 24%[3].

But you should know that this effect is based on the extraction and concentration of β-glucan in oats, which is slightly different from the effect of directly consuming oat bran. The effect is mainly related to the β-glucan content.

3. The proportion of β-glucan that can lower GI

According to the European Food Safety Authority, adding 4g of oat β-glucan to every 30g of available carbohydrates can significantly reduce postprandial blood sugar response[4].

Each gram of β-glucan in oats is accompanied by 13 g of available carbohydrates, a ratio that is not enough to significantly reduce postprandial blood sugar response. Moreover, the effect of eating oat products on glucose and insulin response is largely affected by cooking and processing methods.

Different oatmeal products have huge differences in glycemic index

When cooking rice with whole oatmeal, it is not only difficult to cook, but also difficult to chew. This is because during the cooking process, the presence of the oatmeal shell greatly slows down the water absorption and gelatinization process of the internal starch, and also reduces the contact area between the digestive amylase and the starch during our chewing and digestion process. Because of this, the blood sugar response after eating is also at a lower level.

Image source: provided by the author

However, when oatmeal is flattened, on the one hand, the contact area between starch, water and digestive enzymes in the oats increases during the extrusion process, and on the other hand, some of the starch in "instant oats" has become viscous and easy to be absorbed by the human body because it is cooked in advance. With these two points, the blood sugar response brought by instant oats is naturally high.

But oat bran, which concentrates the high nutrition of oats, has a low glycemic index and is convenient, is a good choice that is often overlooked.

Increased beta-glucan with oat bran

What is oat bran? It's just the thin husk of oats.

The reason why whole grains have more nutritional value than refined grains is that refined grains have the husk removed, leaving only the endosperm, while whole grains only have the husk removed during processing, retaining the husk, endosperm, endosperm, and germ.

The endosperm is mainly rich in starch, while the husk is rich in minerals, vitamins, dietary fiber, etc. [4-7].

Image source: Dietary Guidelines for Chinese Residents (2022)

Compared with pressing oats into oatmeal, pure oat bran contains much more minerals, vitamins, dietary fiber, etc. than ordinary oatmeal. More than 70% of the β-glucan in oats is found in oat bran .

In addition, oat bran is also rich in polyphenol antioxidants[4-7].

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Even a small amount of addition can achieve the desired effect

In fact, you only need to add a small amount of oat bran to see the effect .

Studies have shown that adding 5.9 g of oat bran to 27 g of instant oats (the amount consumed in one adult meal) can reduce the area under the postprandial blood glucose curve by 20%. If you want to reduce the postprandial blood glucose peak by 20%, you only need to add 1.5 g of oat bran to achieve this[8].

Image source: Tuchong

In addition, oat bran is also very versatile. It can be eaten with oatmeal. Adding a small amount to staple foods such as rice, steamed buns, and bread can also significantly reduce the glycemic index and increase the nutritional value .

Suitable for special groups: diabetic patients and pregnant women with high blood sugar can eat it

If you are a person with diabetes or high blood sugar, oat bran can help them control their blood sugar.

A study showed that two commercially available gluten products could significantly reduce the postprandial blood sugar response in patients with type 2 diabetes[8].

Another randomized controlled trial of 112 women with gestational diabetes showed that the intervention group consumed 30g of oat bran daily (half at lunch and half at dinner). Testing was performed 2 and 4 weeks after the start of the trial. The results showed that the average fasting blood glucose and 2-hour postprandial blood glucose levels in the intervention group were significantly lower than those in the control group [9].

Kind tips

There are some scientific considerations to keep in mind when it comes to consuming oat bran. Oat bran is highly regarded for its high fiber content, but consuming too much may cause problems such as bloating.

To avoid discomfort, here are a few suggestions:

1. Gradual adaptation : It is wise to introduce oat bran gradually into the diet. This helps the intestines gradually adapt to the increase in dietary fiber and reduces the possibility of discomfort.

2. Choose the right ratio : There are mixed oatmeal with added oat bran on the market. However, a higher ratio is not always better. Choose products that indicate the ratio of oat bran, but the ratio that suits your stomach is the best choice.

3. Stay hydrated : Dietary fiber needs enough water to pass smoothly through the digestive tract. Maintaining adequate water intake can reduce bloating and discomfort.

References

[1] El Khoury D, Cuda C, Luhovyy BL, Anderson GH. Beta glucan: health benefits in obesity and metabolic syndrome. J Nutri Metab. 2012;1:2012.

[2] BENISI-KOHANSALS, SANEEIP, SALEHI-MARZIJARANI M, et al. Whole-Grain Intake and Mortality from All Causes, Cardiovascular Disease, and Cancer: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies[J]. Adv Nutr, 2016, 7(6): 1052-1065.

[3] Zurbau A, Noronha JC, Khan TA, Sievenpiper JL, Wolever TMS. The effect of oat β-glucan on postprandial blood glucose and insulin responses: a systematic review and meta-analysis. Eur J Clin Nutr. 2021 Nov;75(11):1540-1554.

[4] Wang Hong. Study on the extraction, antioxidant activity and stability of polyphenols from oat bran[D]. Harbin University of Commerce, 2013.

[5] Li Xuefan. Research and development of oat bran and miscellaneous grain instant powder[D]. Shanxi Agricultural University, 2016.

[6] Zhang Yue. Preparation and process optimization of sugar-free oat bran biscuits[D]. Shanxi Agricultural University, 2017.

[7] Wolever TMS, et al. Effect of adding oat bran to instant oatmeal on glycaemic response in humans - a study to establish the minimum effective dose of oat β-glucan. Food Funct. 2018 Mar 1;9(3):1692-1700.

[8] Tapola N, Karvonen H, Niskanen L, Mikola M, Sarkkinen E. Glycemic responses of oat bran products in type 2 diabetic patients. Nutr Metab Cardiovasc Dis. 2005;15(4):255–261.

[9] McGeoch S, Johnstone A, Lobley G, Adamson J, Hickson K, Holtrop G, et al. A randomized crossover study to assess the effect of an oat-rich diet on glycaemic control, plasma lipids and postprandial glycaemia, inflammation and oxidative stress in type 2 diabetes. Diabet Med. 2013 Nov;30(11):1314–23.

[11] Barati Z, et al. The effect of oat bran consumption on gestational diabetes: a randomized controlled clinical trial. BMC Endocr Disord. 2021 Apr 13;21(1):67.

Planning and production

Author: Gu Zhongyi, Director of Beijing Nutritionist Association

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Planning丨Lin Lin

Editors: Lin Lin, Jin Yufen (Intern)