Fibre – the latest “superfood”

Fibre – yes I know, it’s not the most exciting thing in the world but a major study has been investigating how much fibre we really need to be eating and has found there are huge health benefits when we eat more.

  • It reduces the chances of debilitating heart attacks and strokes as well as life-long diseases such as type-2 diabetes.
  • It helps keep your weight, blood pressure and cholesterol levels down.
  • It’s cheap and widely available in the supermarket.
  • It makes us feel fuller and can help digestion and prevent constipation.

The researchers for this study, based at the University of Otago, in New Zealand, and the University of Dundee say people should be eating a minimum of 25g of fibre per day. “The evidence is now overwhelming and this is a game-changer that people have to start doing something about it,” one of the researchers, Professor John Cummings, has told BBC News.

The NHS recommends we should increase our fibre intake to 30g a day as part of a healthy balanced diet. So what does 30g of fibre actually mean?

To increase your fibre intake you could:

  • Choose a higher-fibre breakfast cereal such as plain wholewheat biscuits (like Weetabix) or plain shredded whole grain (like Shredded wheat), or porridge as oats are also a good source of fibre.
  • Go for wholemeal or granary breads, or higher fibre white bread, and choose wholegrains like wholewheat pasta, bulgur wheat or brown rice.
  • Go for potatoes with their skins on, such as a baked potato or boiled new potatoes.
  • Add pulses and legumes such as beans, lentils or chickpeas to stews, soups, curries and salads.
  • Include plenty of vegetables with meals, either as a side dish or added to sauces, stews or curries.
  • Have some fresh or dried fruit, or fruit canned in natural juice for dessert. Because dried fruit is sticky, it can increase the risk of tooth decay, so it’s better if it is only eaten as part of a meal, rather than as a between-meal snack.
  • For snacks, try fresh fruit, vegetable sticks, rye crackers, oatcakes and unsalted nuts or seeds.

Did you know? A small handful of nuts can have up to 3g of fibre. Always choose unsalted nuts, such as plain almonds, without any added sugars.

Find out more:

The secret of resistant starch

“Resistant starch?” I hear you ask, “what’s that?”

If you just happened to be watching that rather interesting programme the other night – “The Truth about Carbs” on BBC1 – you would have discovered that there is a little-known type of carbohydrate called resistant starch. And, just like fibre, resistant starch can help keep bowel cancer at bay.

Most of us love starchy carbohydrate foods like bread, pasta, rice and potatoes but they’re not always good for our health. Although starch is an important part of a healthy diet, it’s easily broken down. As soon as we consume starch the body very quickly starts to digest it, releasing sugars into the blood which in turn causes our bodies to release the hormone insulin. 

Starchy foods such as bread, pasta and potatoes break down easily once eaten and release sugars into the blood.

WHAT IS IT?
Resistant starch is a form of starch that cannot be digested in the small intestine.  Most starch is usually quickly broken down into glucose (which is used for energy) and if we eat too much, the glucose can then be stored as fat. Due to its molecular make up however, resistant starch doesn’t get broken down like normal starch, and instead it passes through the stomach and the small intestine intact until it reaches the large intestine. Resistant starch is then fermented in the large intestine, producing short chain fatty acids which serve as an energy source for colonic cells and our gut microflora. Foods that increase the amount of short chain fatty acids in the colon are thought to be beneficial to health by helping to prevent the development of abnormal cells in the gut.

Resistant starch is naturally present in some foods such as bananas, potatoes, grains, pulses and seeds and is also produced or modified commercially and incorporated into some food products.

Eat green! Unripe bananas contain lots of resistant starch but this becomes digestible as the bananas ripen. Cooking will also destroy the resistant starch.

There are several different types of resistant starch:

  • RS1: This is inaccessible to digestive enzymes due to the physical barriers formed by cell walls and protein matrices. Present in bread, seeds and pulses.
  • RS2: This type of resistant starch is protected from digestion due to its crystalline structure. Present in potatoes (higher amounts in raw versus cooked), bananas (higher amounts in unripe fruits).
  • RS3: This is retrograded starch which is formed when starchy foods such as potatoes and pasta are cooked and then cooled.
  • RS4: This is a chemically modified starch. Present in foods containing modified starches such as some bread and cakes.

Note: In addition, two different components have been proposed as RS5. Either amylose–lipid complexes, which either form during processing or are created artificially; or resistant maltodextrin which is processed to purposefully rearrange starch molecules.

Researchers have known about resistant starch for over twenty years now, so why the sudden excitement?

RS3 – Why we are getting excited!

Back in 2014, the BBC’s “Trust me I’m a doctor” programme conducted an experiment with Dr Denise Robertson, from the University of Surrey and ten volunteers. The team were well aware that if you cook and cool down starchy foods, your body will treat it much more like fibre, creating a smaller glucose peak and helping feed the good bacteria that reside down in your gut. You will also absorb fewer calories. However what no-one knew was what would happen to the resistant starch if you reheated the cold food up again.

The volunteers had to undergo three days of testing in all, spread out over several weeks. On each occasion they had to eat their pasta on an empty stomach. The volunteers were randomised to eating either hot, cold or reheated pasta on different days.

On one day they got to eat the pasta, freshly cooked, nice and hot with a plain but delicious sauce of tomatoes and garlic. On another day they had to eat it cold, with the same sauce, but after it had been chilled overnight. And on a third day they got to eat the pasta with sauce after it had been chilled and then reheated.

On each of the days they also had to give blood samples every 15 minutes for two hours, to see what happened to their blood glucose as the pasta was slowly digested.

THE RESULTS
Just as expected, eating cold pasta led to a smaller spike in blood glucose and insulin than eating the freshly boiled pasta had. But unexpectedly, the team found that cooking, cooling and then reheating the pasta had an even more dramatic effect. Or, to be precise, an even smaller effect on blood glucose, reducing the rise in blood glucose by 50%. This certainly suggests that reheating the pasta made it into an even more “resistant starch”. It’s an extraordinary result and one never measured before.

The health benefits of resistant starch

  • When regular starch becomes resistant starch, most of the sugars it contains aren’t released in your gut and so your body will take in fewer calories from the same food.
  • Because less sugar is released into the blood stream from this resistance starch, there’s less of a blood sugar spike. In turn, this reduces the levels of insulin in the blood.
  • Resistant starch is indigestible and so shares many properties with fibre, helping food pass through the gut and generally improving digestion.
  • Once it reaches the lower gut, resistant starch feeds our beneficial bacteria, which in turn produce chemicals which can help our immune systems, cardiovascular health and many other benefits.

Freeze first then toast: make your bread work for you!

We love our bread. And it can be hard to give that up. But maybe we don’t need to. If you can’t stop eating bread, you can make the bread healthier for you by simply freezing it then toasting it. This turns some of the easily digestible starch into resistant starch. The act of freezing and then toasting means that your body gets far fewer calories from the bread. In effect, the resistant starch feeds your gut bacteria rather than feeding you. It really is that simple!

Thanks to:
BBC Trust me I’m a Doctor
BBC The truth about carbs
British Nutrition Foundation

Why do some people put on weight? It could all be down to your gut!

When it comes to nutrition there is so much information out there that it can be easy to become bamboozled. In the last few years, food science has come on in leaps and bounds and we’re only now beginning to really fully understand how our bodies work and process food.

We all know that eating a nutritionally balanced diet is good for us. But even when sticking to a so-called good diet, some of us can still struggle to lose those stubborn pounds. To make matters worse, there are some people who are lucky enough to be able to eat pretty much what they want, and never seem to put on weight! Ah, if only! But could there be a reason why this is?

I was very excited to read the following article from the BBC TV programme “Trust me I’m a doctor”. Here is the article:

Dr Saleyha Ahsan from the BBC’s “Trust me I’m a doctor” series travelled to Israel to take part in a study, being carried out by the Weizmann Institute in Rehovot and led by Professor Eran Segal and Dr Eran Elinav. And it is producing some very exciting results!

THE STUDY

  • Recruited nearly 1000 people so far to take part;
  • Each participant has provided detailed health and medical data;
  • Participants take part in a week-long close examination;
  • This looks at how their blood sugar levels react to different foods.

During the week, participants’ blood sugar levels are measured constantly by a glucometer placed under the skin. Their sleep and activity levels are monitored by a wrist-band, and they are given an app to record their mood, feelings, sleep and exercise regimes and what they eat. Throughout the week, their meals are planned – some are given to them as standard foods that everyone tries. Others they are allowed to choose, but they have to weigh it all accurately, and record it in precise detail. Each person in the study has also given a stool sample. From this, the researchers analyse the gut bacteria living inside each person. Our gut bacteria are unique to us – it is almost like a ‘fingerprint’ of a person – but, crucially, they can change.

THE FINDINGS

The researchers at the Institute have found several startling things during their study:

1. Every person reacts differently to different foods.
This has been a real surprise, as the textbooks have long suggested that some foods (eg. white bread) give all of us a sudden blood sugar ‘spike’ (which is bad for our health – increasing our risk of Type 2 diabetes and obesity), whilst it has been thought that other foods (such as wholegrain rice) give all of us less of a ‘spike’. This has recently been called ‘high GI’ or ‘low GI’ (for foods that give people a spike or not, respectively). However, the standard group of people on whom these foods have been tested has long been 10 – and now with 1000 people’s data it is clear that everyone is very different.

2. The team have been able to make firm links between a person’s individual response to food, and to the gut bacteria that they have.
Using their huge amounts of data from the participants, the team have come up with a computer algorithm that can now take a person’s individual gut bacteria composition, and from it, predict how their blood sugar levels will react to a whole range of foods. They have done a study to test the accuracy of this algorithm, and it does indeed appear to predict ‘good’ and ‘bad’ foods for different individuals based only on their gut bacteria. This goes to show how important our gut bacteria are in regulating our responses to food, and indeed for our health.

3. The team have carried out a small study in which 25 people had a ‘good’ and ‘bad’ diet predicted for each of them by the algorithm – with very encouraging results.
The participants then ate only the ‘good’ for one week and then the ‘bad’ for another – and weren’t told which was which (and because our reactions are so individual, some foods were ‘good’ for one person and ‘bad’ for another). Not only did their blood sugar react as predicted to the different foods, but the team saw changes in the gut bacteria of the volunteers over just the week. Although the roles of different groups of bacteria in our health is still very much uncertain, the changes that they saw during the week of ‘good’ food appeared to be beneficial.

This suggests that we may not only be able to personalise our diets to be healthy for each of us individually, but that we might be able to change our responses to food.

THE FUTURE

Professor Segal and Dr Elinav hope to be able to make the results of their work available to everyone, worldwide. They hope that they will in the future be able to take stool samples, sent through the post, and provide a personalised diet plan in return – listing foods which are predicted to give that person an unhealthy blood sugar spike, and those which are likely to maintain more stable, healthy blood sugar levels.

These will, of course, have to be eaten within a normally balanced diet – it doesn’t mean that if chocolate turns out to be on your ‘good food’ list, you can live on it and be healthy! Nonetheless, the fact that ‘good’ foods for particular individuals usually seem to include some that people very much like, it appears that these personalised diets are much easier for people to adopt than traditional restrictive ones.

The team are also now studying the longer-term effects of diet on gut bacteria. It is possible that as the gut bacteria change in response to the diet (which happens within days or weeks), that the diet could then be modified, or relaxed.

Exciting stuff! If you are interested in finding out more about this study, please check out the following links:

The Personalised Nutrition Project
Trust me, I’m a doctor