Many people still need to consume more fruits, vegetables, and grains, even though the health benefits of these foods are well-known. For example, less than 10% of Americans meet the daily recommendations for whole-grain intake.
Numerous studies have shown that including plant-based foods in your diet can help reduce the risk of chronic diseases like type 2 diabetes, cardiovascular problems, and certain cancers.
Researchers at the University of Minnesota in St. Paul, MN, have recently uncovered additional advantages of insoluble fibre beyond its role in improving digestion and stool regularity.
In their recent review, experts found that insoluble dietary fibre (IDF) contains bioactive compounds that can support health in various ways. Moreover, these fibres can enhance the nutritional value.
of different foods by adding them to them.
In addition to peels, pulp, and pomace, which are rich in fibre and bioactive substances, this type of fibre can be easily obtained from byproducts of food production.
The research highlights the importance of recognising fibre and the bioactive components found in plant-based sources as valuable contributors to human health.
Researchers thoroughly searched the Ovid Medline, Ovid Agricola, and Scopus databases to gather information on bioactive compounds. They examined 30 different sources of insoluble dietary fibre (IDF), including rice, wheat, lentils, mangoes, beets, and berries. The assessment focused on measuring total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (AA) in these sources.
In this study, 64 bioactive compounds were identified across the various IDF sources. These compounds belonged to phenolic acids, flavonoids, and non-flavonoid compounds. The researchers noted that bioactives tend to be concentrated in different parts of different plants. For example, fruits might have more in the pulp, while vegetables might have more in the skin. The researchers aimed to expand their investigation beyond dietary fibre and sought published information on bioactives from various plant-based foods. Most of this information was found in plant science journals rather than nutrition journals, leading to an uneven and non-representative sampling.
It has been observed by the team from the University of Minnesota that IDF can be found in specific plant foods and various plant tissues. These different plant tissues can contain varying fibre types; some tissues have fibre while others do not.
It was also noted that the content of IDF and bioactives can differ depending on how the IDF sources are extracted, processed, and treated.
For example, different extraction methods resulted in varying amounts of carotenoids for sweet corncobs and Mexican apple pomace powders. Additionally, bioactivity was affected by processing temperatures.
Preserving the bioactivity of lentil-fortified pasta was difficult, as boiling caused a 30% loss in phenolic content.
Although some IDF compounds weren't preserved in the foods examined, many still demonstrated improved nutritional value.
The researchers noted that most commercially available ready-to-eat foods are primarily baked goods with limited nutritional benefits.
However, when plant sources were incorporated into cookies, it not only raised the levels of IDF, TPC, and TFC in the cookies but also reduced carbohydrate content.
While adding dietary fibre to foods can offer advantages by increasing bioactive content, it's important to note that it can also alter the texture of certain products.
In some cases, this alteration can be beneficial. For example, when apple pomace was incorporated into yoghurt during the study, it resulted in a firmer and more consistent product.
The cooking process reduced some foods' bioactivity, but it remained higher than in the control food. As a result, the researchers concluded that incorporating insoluble dietary fibre (IDF) "may be useful as a supplement for consumers."
Kate Randall, a registered dietitian nutritionist at WellTheory who was not involved in the study, explained that isolated insoluble fibres from plant foods can offer various benefits, including improved digestive health, weight management, blood sugar control, and cardiovascular health.
However, she also cautioned that isolating insoluble fibre could be costly, labour-intensive, and may involve using chemicals or methods that could alter its natural properties.
She emphasised that in many cases, different components in whole plant foods work together synergistically to provide health benefits. Isolating a single component may overlook the combined advantages of the entire food matrix.
Researchers at the University of Minnesota aim to enhance the nutritional value of plant-based foods. Their work challenges previous beliefs regarding the benefits of dietary fibre.
While past thinking primarily favoured soluble dietary fibre for its physiological benefits and considered insoluble fibre mainly affecting bowel function, current research suggests a shift in this perspective.
This new understanding emphasises the importance of increasing our consumption of plant foods to meet recommended dietary fibre intake levels, highlighting the potential of insoluble dietary fibre and bioactive compounds in improving overall nutrition.
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