Nutrition experts call for dietary fiber recognition as an essential nutrient

Ōtākou Whakaihu Waka nutrition experts are calling for dietary fiber to be officially recognised internationally as an essential nutrient - the first 'new' essential nutrient in more than 50 years.

The researchers say fiber should sit alongside nutrients already considered essential for humans, such as certain amino acids and vitamins.

Co-author Associate Professor Andrew Reynolds says increasing our dietary fiber intakes would deliver greater health benefits in Aotearoa New Zealand than increasing any other essential nutrient, given that our current fiber intakes are below World Health Organization (WHO) recommendations.

"The disease burden associated with diabetes, heart disease and colorectal cancer would be expected to be appreciably reduced by such a dietary change." 

In a paper published in Nature Food, Associate Professor Reynolds and Professor Sir Jim Mann, both from the Otago Edgar Diabetes and Obesity Research Centre, along with Emeritus Professors Gerald Tannock (Otago) and John Cummings (University of Dundee) argue that recent advances in our understanding of dietary fiber mean that it now meets the criteria required for essentiality.

Their argument is supported by more than 100 years of research into its chemistry, physical properties, physiology, and metabolic effects as well as more recent meta-analyses and clinical trials – many of which were conducted at Otago.

Associate Professor Reynolds says the research team examined if there were any causal associations between dietary fiber intake and health outcomes and found overwhelming evidence of benefit.

"Looking across multiple studies, we see that when people increase fiber intakes, their body weight, cholesterol, blood sugars and blood pressure all improve. When following people over decades, we see those with higher fiber intakes get less heart disease, less type 2 diabetes, less colorectal cancer, and are less likely to die prematurely," he says.

"Focusing on increasing intakes of high-fiber foods such as whole grains, legumes, vegetables and whole fruit is likely to deliver substantial health benefits.

"The more that fiber is recognized and prioritized, the better. If people focus on increasing fiber in their diet then food producers are more likely to reformulate products to have more fiber, making it even easier to increase your fiber intake. There are a lot of potential benefits, should fiber be recognised as essential."

To be recognised as essential the nutrient must be beneficial to human health, not be produced by the body itself, and absence of the nutrient would result in a measurable deficiency state. 

To date it has been the lack of a deficiency state that has prevented fiber from being recognised as essential. The answer to this previous limitation, the authors propose, happens to be one of the most exciting fields of health research at present.

Co-author Professor Mann says, "in some ways, it's quite simple".

"The gut microbiome exists almost exclusively on the dietary fiber we eat. A healthy gut microbiome is linked to all sorts of health benefits, with more discovered and understood each day."

Previous work of co-author Professor Tannock has shown that low fiber intakes result in a relatively unfunctional gut microbiome, with increasing fiber intakes restoring microbiome function and its relationship with the human host.

Currently, New Zealanders eat an average 20g of fiber a day, while the WHO guideline recommends at least 25g per day. 

Associate Professor Reynolds says just 5 grams more per day on average would meet that minimum healthy intake of fiber for New Zealanders.

There are a number of simple and inexpensive ways Kiwis can add fiber to their diet.

Whole grains are a great source of fiber. Oats are one of our most accessible whole grains - they are grown in New Zealand - alongside wholegrain bread and wraps." 

Associate Professor Andrew Reynolds

Tinned legumes are also an excellent source of fiber, as well as being cheap and easily combined with meals.

"I supplement or replace meat in recipes with beans all the time, such as cannellini beans or butter beans for chicken, kidney beans or black beans for mince and lentils are like a stealth source of fiber as they tend to break down quickly when cooked.

"Most vegetables are a good source of fiber, it doesn't matter if they are fresh, frozen, or tinned," says Associate Professor Reynolds.

Professor Mann says recognising dietary fiber as an essential nutrient will help to ensure that dietary guidelines, nutrition education programmes and health professionals provide greater emphasis on adequate intakes of fiber, with reformulation of food products and changes in food labelling likely to follow.

"Increased intakes of fiber, which would be expected with greater awareness, have the potential to appreciably reduce the huge burden of non-communicable diseases facing Aotearoa New Zealand."