In the news last week we saw many articles similar to this one from the BBC website. These articles relate to a World Health Organisation (WHO) funded review in the Lancet that looked at the amount of dietary fibre people eat and how it relates to their health and risk of disease.
The general impression of the WHO review suggests that we all need to eat at least 25g of fibre per day to lower our risk of disease. And, that whole grains can form a substantial portion of this amount.
I have been talking about the benefits of eating a diet rich in fibre for years. And I’m sure that many people are aware that eating more dietary fibre is good for their health.
I also agree that some whole grains can form part of a healthy diet if a person is not intolerant to them. After all, whole grains can form part of a healthy Mediterranean type of diet.
As an aside, I would add here that it is probably better to rotate different grains and not eat the same grain such as wheat, day after day, as many people do.
But, while many reporters seemed to focus on the value of whole grains, the WHO review talks about both whole grains and dietary fibre from other sources such as vegetables, pulses and fruits. And, digging a bit deeper into the research, reveals that the quality of the evidence for the different fibre sources is not the same. In fact, the studies of whole grains and risk of disease were of substantially lower quality than the studies on other sources of fibre.
Whats more, the researchers admit that many of the studies that they included in their work were from a time when the type of wholegrain foods available were probably quite different to the present day. For example, looking around the supermarket shelves today, it’s quite easy to find ‘wholegrain’ highly processed foods. The reality is that these processed foods bear little resemblance to the original wholegrains they were made from. Whole grain crackers, whole grain pastas, processed wholegrain breakfast cereals and other ‘wholegrain’ processed foods are not the same as whole grains. And they have different affects on the human body. For instance, it is unlikely that these processed foods offer the same benefits to the gut microbes as unprocessed whole grains.
In reality the benefits of eating more dietary fibre probably relate more to the affect of fibre on our gut microbes. Diets rich in dietary fibre encourage the growth of a healthy and diverse population of microbes, that can have positive effects on our own health.
Our gut microbes protect us from disease causing bacteria and fungi. They help to improve our immune system. They produce several vitamins for us. They also have a role in detoxification of various toxins that might enter our body. And different species can have different roles. So, by having a healthy and diverse gut microbiome we are more likely to reduce our risk of disease. Is this the true benefit of dietary fibre? If so, we should choose our foods carefully to feed and promote a healthy microbiome.