Magical dietary fibres

hamburger_(Tony_Evans)

Dietary fibre can influence appetite (Photo: Tony Evans).

We have all heard the “eat more fibre” mantra and wondered what this is all about. So did scientists. Sure we have long known it is good for gut health and function. Recently with the exploration of the gut microbes – the microbiota – we have learnt that dietary fibre can support survival and growth of the good bugs. That we have written about before.

Now scientists have found another piece of the puzzle. Some of the fermentation products produced by the gut microbes from the dietary fibre that our own enzymes cannot digest have the potential to influence our appetite. That is incredible and provides a further insight into the obesity conundrum.

The new mechanism

Obesity is currently one of the most serious global threats to human health. Susceptibility to obesity is determined by genetic background, diet, and lifestyle. Now it has become apparent that the resident intestinal microbes in the large intestine also play an important role.  During the process of microbial fermentation of non-digestible fibre, the short-chain fatty acids acetate, propionate and butyrate are formed.

While short-chain fatty acids can serve as an energy source, the scientists showed that they also act as signaling molecules for the free fatty acid receptor 2 (FFAR2) found in enteroendocrine L cells in the large intestine. These specialised gut cells secrete the appetite suppressing hormone peptide YY (PYY). FFAR2 signaling was found to drive an expansion of the PYY cell population within the large intestine, leading to increased circulating PYY. This is associated with a reduction in food intake and protection against diet-induced obesity.

Evidence points to the production of short-chain fatty acids by the gut microbiota as an important appetite regulatory signal.

So what are fibres?

almonds

Almonds are good sources of dietary fibre.

Just to be clear, dietary fibre is the indigestible portion of food derived from plants. Chemically, dietary fibre consists of non-starch polysaccharides such as arabinoxylans, cellulose, and many other plant components such as resistant starch, resistant dextrins, inulin, lignin, chitins, pectins, beta-glucans, and oligosaccharides. Food sources of dietary fibre are often divided according to whether they provide predominantly soluble or insoluble fibre.

Soluble fibre is found in varying quantities in all plant foods, including in a range of legumes, in oats, rye, chia, and barley, in several fruits, in vegetables, in root tubers and in nuts, with almonds being the highest in dietary fibre.

Sources of insoluble fiber include whole grain foods, wheat and corn bran, legumes such as beans and peas, nuts and seeds and vegetables such as green beans, cauliflower, zucchini and celery.

So there you have a wide variety of healthy foods with the potential of reducing your hunger pangs and alleviate the risk of overweight and obesity.

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Rosemary benefits – believe it if you must

diet_(Christina_Roervik

Benefits of a balanced diet.

I might be a bit repetitive here, but allow me to be clear at the beginning of this blog. There are no magic individual foods.

Sure there are good and bad foods that might tilt your habitual diet towards being more beneficial or detrimental to health. But it is the overall balance that is most important for a healthy life.

With that caveat in mind, we are going to look at purported health effects of rosemary, a perennial woody herb.

The ageing population of Acciaroli

There’s a little village in Italy called Acciaroli that has been doing the rounds in the international press during 2016. The reason: an unusual number of the small southern Italian township’s population is over the age of 100. And they have the micro-circulation of significantly younger people. These are the small blood vessels that send nutrients to the brain and organs and pull out metabolic waste products, but which tend to deteriorate with age.

Could it be something about the air, the ocean, the mountains, the hills, the olive and berry trees?

Or maybe the food. Scientists found that at every meal they’re eating anchovies, and they eat them fried and greasy. Typically, that will be washed down with a glass or two of wine. Greasy anchovies and wine – maybe a little far fetched for supporting a long life.

What about rosemary? Well, research recently released showed the almost daily consumption of rosemary by the Acciaroli population – infused in the local olive oil, cooked in pasta dishes and chewed raw. And this habit has been linked to improved micro-circulation and a concomitant effect on longevity.

The benefits of rosemary

rosemary

Potential health impact of rosemary consumption.

The first benefit – rosemary tastes great. Italian cooking uses rosemary in abundance. It’s an easy and reliable herb to grow. A light prune once a year will keep the rosemary bush in shape. One plant will provide more than enough for regular use. It works in both savoury and sweet meals. Rosemary, along with roughly chopped garlic, onion, carrots and celery sautéed in olive oil and cooked, forms ‘soffrito’ – the basis for many different stocks, soups, sauces and other dishes.  It can also be used in desserts, like a panna cotta, with some grappa.

The second benefit – rosemary contains a number of phytochemicals, including rosmarinic acid, camphor, caffeic acid, ursolic acid, betulinic acid, and the antioxidants carnosic acid and carnosol. A lot to take in, but let’s focus on rosmarinic acid. Research has shown that it has a number of interesting biological activities, e.g. antiviral, antibacterial, antiinflammatory and antioxidant. The presence of rosmarinic acid in medicinal plants, herbs and spices has beneficial and health promoting effects. In plants, rosmarinic acid is supposed to act as a preformed constitutively accumulated defence compound. If you don’t like rosemary, rosmarinic acid can also be found in many other culinary herbs such as basil, lemon balm, marjoram, sage, thyme and peppermint.

The third benefit – it is also a good source of iron, calcium, and vitamin B6. Although as a herb it is consumed in such small amounts that this might not be important enough to influence health.

No harm done

Convinced yet? Maybe not and the researchers also kept an open mind. Further studies are underway to further explore the findings. But in the meantime there’s certainly no harm in increasing your consumption and use of rosemary or related herbs.

A bathtub of sugary soft drinks

bathtub

Consumption of sugar sweetened beverages equal a bathtub worth per year.

Can you believe it, when analysing data collected through the UK National Diet and Nutrition Survey, Cancer Research UK found that teenagers aged between 11 and 18 drink almost a bathtub full of sugary drinks on average in a year. To be more precise the average soft drink consumption for this group equalled 77L per year. That is actually a very small bathtub as they normally vary in size from 77L to say 170L. However, when taking a bath the water volume is most often just half that so drinking a bathtub of soft drinks per year is a fairly accurate estimate.

The figures shed light on the extreme sugar consumption of UK teenagers in that they eat and drink three times the recommended limit, with sugary drinks being their main source of added sugar. This contributes to the development of overweight and obesity and obese children are around five times more likely to grow into obese adults. The situation is similar in many other countries. Sales of sugar sweetened beverages in Australia equates to 75L per year for every adult and child, while overall consumption of sugar sweetened beverages per person in the USA has been estimated at 115L per year.

And on it goes. So what can be done?

Taxing sugar in soft drinks

In an effort to reduce the detrimental effects of consuming excessive volumes of sugary drinks, a tax has been suggested similar to the tax on tobacco. Several countries have already imposed a tax while others are in the process to do so.

Norway has had a generalised sugar tax on refined sugar products, including soft drinks, in more than 35 years. Hungary’s tax introduced in 2011 has seen 22% of people reduce energy drink consumption and 19% of people reduce their intake of sugary-sweetened soft drinks. France introduced a targeted tax on sugary drinks at a national level in 2012 and found that sales of soft drinks declined in the year following the introduction of the tax, following several years of annual growth. Annual sales of soft drinks in Mexico declined 6% in 2014 after the introduction of a tax in 2013.

South Africa, Ireland and the United Kingdom have all decided to introduce soft drink taxes in 2017-2018. The United States does not have a nation-wide soft drink tax, but a number of cities have or will soon introduce their own taxes. There has been a growing debate around taxing soft drinks in various cities, states and even in congress in recent years. This debate alone has raised awareness of the problem and soft drink consumption is on the way down.

Other countries are still debating the benefits of a sugar tax. In Australia there is an expert group proposal to introduce a tax of 40 cents per 100 grams of sugar, which would lift the price of a two-litre bottle of soft drink by about 80 cents.

What about diet beverages?

dietsodadrinker

Diet beverages might not be the solution to reduce the incidence of obesity.

The reduction in the consumption of sugar sweetened beverages is all good if it is replaced by water. But what about diet beverages? Sugar substitutes like aspartame are supposed to promote weight loss, but a number of clinical and epidemiologic studies have suggested that these products don’t work very well and may actually make things worse. This is quite confusing as energy intake is reduced. However, there has been some evidence that artificial sweeteners actually can make you more hungry and thus may be associated with increased energy consumption.

Now a research team has found a possible mechanism explaining why use of the sugar substitute aspartame might not promote weight loss. Their report show how the aspartame breakdown product phenylalanine blocks a gut enzyme called intestinal alkaline phosphatase (IAP). And IAP is normally protective in that it has been shown to prevent obesity, diabetes and metabolic syndrome.

The researchers also showed that mice receiving aspartame in their drinking water gained more weight, had higher blood sugar levels, which indicates glucose intolerance, and higher levels of the inflammatory protein TNF-alpha in their blood, which suggests the kind of systemic inflammation associated with metabolic syndrome.

So what to do?

It is quite clear that just a debate around the detrimental effects of excessive consumption of sugar sweetened beverages can have an effect. Add to that an increase in the price and the benefits are obvious as shown already in several countries.

But it is equally important that the new choice of beverage doesn’t add to the problem. The use of artificial sweeteners might not be as innocent as could be expected.

Known impossibles

There are a number of known knowns say food safety types and they insist that we follow their sometimes impracticable or impossible advice. But is scientific opinion always right?

Impossible hand washing advice

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The ever important hand wash (Photo: Marmotto)

They want us to wash our hands for an impossible 20 seconds. It doesn’t sound much but you stand there with cold hands since it might take more than 20 seconds for the warm water to flow through the long pipe.

Well, Health Canada is a little more sensible reducing the washing time to 15 seconds but insisting it should be warm water. However, contrary to popular belief scientific studies have shown that using warm instead of cold water has no effect on reducing the microbial load on hands. Scientific results also show that soap is more effective than water only and drying with a paper towel is preferable to using hand driers for removing the bugs on your hands.

So the practical recommendation? Above all wash your hands before preparing food with a method you feel comfortable with.

Impossible fruit and vegetable advice

They want us to eat 2 portions of fruits and 5-6 portions of vegetables per day. Translated to weight that would be 300 grams of fruit and 450 grams of vegetables or a full 750 grams in total on a daily basis. Are they mad, there will be no place for anything else.

However, to be fair a meta study showed that a diet with more than five servings of fruit and vegetables reduces a person’s risk of developing conditions such as heart disease and diabetes. But according to the Australian Bureau of Statistics, in 2014-15, while half of Australians aged 18 years and over met the guidelines for recommended daily serves of fruit (2 or more serves), only 7% met the guidelines for serves of vegetables (5-6 or more serves). A paltry one in twenty adults met both guidelines.

See what I am saying? And the situation is similar in many other countries. So the practical recommendation? Sure, try to increase your consumption of fruit and vegetables. An extra leaf of lettuce and a tomato on your lunch sandwich might help.

Impossible rule change for dropped food

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A dropped slice of chocolate cake might be rescued.

And now we cannot follow the 5-second rule any longer, that is if you drop a piece of food on the floor but pick it up within 5 seconds you are safe to still eat it. What a waste of food. Just imagine you drop a nice slice of chocolate cake on the floor but pick it up immediately before the dog can take it and you still have to throw it away. No way I would say and by the way chocolate is dangerous for dogs so you have to be quick anyway.

Though scientists have backed up the new advice. They experimented with different food and contact surface types and concluded that the 5-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food. Bacteria can actually contaminate the food instantaneously. The scientists demonstrated that the 5-second rule was relevant in the sense that longer contact time resulted in more bacterial transfer, but factors like the nature of the food and the surface it falls on are of equal or greater importance.

And the practical recommendation? Obviously it doesn’t help to be quick, the bugs will still beat you. But you might wash off a hard surface and scrape off a little bit of the chocolate cake before eating the rest. If the food is still to be heated there is no problem. But a buttered sandwich surface down might be best to put in the garbage bin.

Impossible fiddling with temperature probes

They also say that when you prepare your hamburgers you cannot rely on your visual senses anymore. That is colour, firmness and smell are not considered sufficient. You have to use a digital thermometer and make sure that the centre of the hamburger reaches 71ºC. You have to fiddle with the thermometer tip sticking it into the side of the burger to reach all the way to the middle while at the same time avoiding getting your fingers burnt. And you have to do it for each burger separately.

Scientists explain that heat-induced denaturation of myoglobin, responsible for the characteristic dull-brown colour of cooked meats, is influenced by a multitude of factors. The interactions between these factors critically influence the internal cooked colour and can confuse the consumers who often wrongly perceive cooked colour to be a reliable indicator for doneness and safety. But there are some hope. Another scientific study agreed that colour alone was a misleading guide for the core temperature of a hamburger. However, when including texture of the meat and clarity of the meat juice in the judgement the situation improved.

And the practical recommendation? It might pay off to invest in a meat thermometer but once familiar with the cooking time needed to reach the recommended core temperature a bit more flexibility might be possible. As long as you promise to not eat rare or medium-rare hamburgers.

Impossible cross-contamination prevention

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Use different cutting boards to avoid cross-contamination. 

And there’s more. You are not allowed to keep the same cutting board and utensils you just used to cut your raw chicken for subsequently preparing your vegetables to eat without further heating. Come on, the food will be cold before you have done all the washing up.

Well, I am sorry to say that scientists are unequivocal on this point. You just have to use different utensils for raw and cooked meat and utensils that have been in contact with raw meat can never be used for produce that will be consumed without further heating.

Known unknowns and unknown unknowns

For all the food safety rules for known knowns, there is little said for the known unknowns that we might worry more about.

What about the bisphenol A in our food packaging material and cash register receipts? There have been several reports of damaging endocrine effects on unborn babies, but this science is still controversial so you’re on your own on this one.

And of course nothing can be said about unknown unknowns.

Acrylamide, a carcinogen, has been present in some heated foods since time memorial following the invention of fire. But it was not until the late 20th century that it was detected by a coincidence. Since then there have been many attempts to reduce its presence in food.

What else is lurking around? That is impossible to say so better relax. Overall, a balanced diet is the best protection for a healthy life. Stay sufficiently safe to stay healthy might be the best motto!