A series of systemic reviews and meta-analyses of studies recently published in The Lancet concluded that people who eat a diet high in fibre and whole grains have a lowered risk of several non-communicable diseases (NCDs) – including diabetes and colorectal cancer – compared to those who don’t.

The data included in the study spans a period of almost 40 years and comes from over 4,600 adult participants. It highlights the health benefits of consuming at least 25 to 29 grams of dietary fibre a day.

The research was commissioned by the World Health Organisation (WHO) to help update dietary guidelines for daily fibre intake and to find out the types of carbohydrates that best protect against NCDs and weight gain.

 

The study

Researchers analysed data from 185 observational studies and looked at the effects of increased consumption of fibre and whole grains on NCDs such as cardiovascular diseases, type 2 diabetes and colorectal cancer, as well as cancers that have been linked to obesity like breast, endometrial and oesophagal cancer.

And the results were pretty astounding: For every 8 gram-increase of fibre intake (the amount found in one and a half medium sized pears), the risk of type 2 diabetes, coronary heart disease and colorectal cancer was found to be slashed by five to 27 per cent.

Photo by Tara Evans

As far as whole grains go, every 15 gram-increase in intake was linked to two to 19 per cent fewer incidences of those diseases as well as death. Plus, increasing whole grain intake even further was linked to a 13 to 33 per cent lower risk of NCDs

Low glycaemic index and low glycaemic-load diets were also found to have protective effects against disease, but those effects were limited and were only confined to type 2 diabetes and stroke.

Researchers think that the study found the effects of those diets to be limited because low glycaemic index foods often contain added sugars, saturated fats and sodium.

One of the study’s authors, Professor Jim Mann of the University of Otago, New Zealand, says that the health benefits of fibre have been supported by over a century of research into its properties and its effects on the human body.

He says that because fibre-rich foods require chewing and mostly keep their structure once reaching the gut, they can help us feel more full after eating and that this can help with weight maintenance as well as regulating blood glucose and lipid levels. He also adds that the breakdown of fibre by bacteria in the large intestine itself provides a number of benefits, such as protection from colorectal cancer.

The authors of the study did note, however, that the findings mainly relate to foods that are naturally rich in fibre as opposed to synthetic or extracted fibre sources like fibre powders. They also added that although the study itself didn’t find any risks related to having a high fibre intake, fibre-rich diets may negatively affect people with iron and other mineral deficiencies and that high whole gain intake could lower their iron levels even further.

A Researcher’s Take

This study might serve as a bit of a surprise to some of the public in the current age, where low-carb diets attract hordes of followers and grains are demonised. But, it’s not without its limitations, according to Professor Gary Frost of Imperial College London, UK.

Professor Frost said that although the methods used in the study give us a good look at the benefits of fibre and that those benefits fall in line with what has been seen in past studies, one of the flaws of this study is that it did not consider the total carbohydrate intake of the participants. Needless to say, this could affect the reliability of the results.

Photo by Justino Sánchez

Another issue he highlighted is that even though the lack of association between eating a low GI and GL diet and a lowered risk of NCDs can also be seen in another recent systemic review, the number of studies on this subject that have been used in this study are small and show mixed results. This, he says, means that we need to take care when making conclusions on this subject.

Professor Frost also said that there was no objective way to measure participants’ fibre intake in the study. This, he said, meant that researchers had to rely on participants’ own reports and that those can be mistaken.

Despite these shortcomings, Professor Frost said that the study provided “compelling evidence” of the positive effects of dietary fibre and whole grains on disease risk. He also said that this information should be used to influence public health policy.

So whole grain pasta is on the menu, friends, let’s celebrate!

Written by Tesneem Ayoub 

Sources:
https://www.sciencedaily.com/releases/2019/01/190110184737.htm
https://www.healthline.com/health/parenting/high-fiber-foods-for-kids#5 

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