Iron – best in moderation


You can eat fruit and vegetables to your heart’s content.

I like to promote a varied and balanced diet – all in moderation. But no, I get criticised for recommending and not defining a balanced diet. I think it’s self evident, a bit of everything without overindulging in any particular food or food group, possibly with fruit and vegetables a free for all exception.

But food “nazis” want to air their opinions. They used to say that you should seriously reduce your fat intake, particularly saturated fat. Then they changed their tune and gave the all clear to fat, but instead banned carbohydrates in general and plain sugar in particular.

Extreme ketogenic diet

According to the latest fad you should try to get your metabolism into a ketogenic state by removing almost all carbohydrates from your diet. That way you force the body to burn its own fat and produce ketones that the brain can use for its energy needs. You will easily lose weight, mainly through water loss, and feel energised, they say.

Inspired by the US president who in early 2018 used the “shit” word I will indulge in some profanity and say “bullshit”. While a ketogenic diet may be an appropriate short-term solution under strict supervision for some, and will result in weight loss, it could lead to serious health complications over time. In the long run, a keto diet will do more harm than good for a majority of the population, especially if they have any underlying kidney or liver issues.

Ketogenic diets practically eliminate an essential food group from your diet, which means you are not going to be getting all of your daily nutritional needs from this diet. This diet is also very low in fibre, which can cause your digestive system to slow down. You will be forced to take mineral supplements or vitamins to hit your daily needs that you will not be getting from a ketogenic diet.

The essential iron

red blood cells

Our red blood cells need iron to function.

That’s a long winded introduction to get us to iron and the important balance of iron intake. Iron is an essential component of life. It is responsible for transporting oxygen in red blood cells, for activation of enzymes involved in DNA production and for energy production in the cell. Iron deficiency impairs oxygen transfer throughout the body, cell division and energy production yet, excess “free” iron that is not bound to any protein may trigger oxidative stress that can be toxic to the organism.

So it is not the case of the more the better. Both iron deficiency or overload may lead to damaging effects by mediating inflammatory diseases, cancer and neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease. And remember that all bugs, including the disease causing pathogens, love iron. Acquiring iron is crucial for the development of any pathogen.  Too much iron through food or supplements encourage pathogen growth.

Complex mechanisms have evolved that illustrate the longstanding battle between pathogens and humans for iron access. Ferritin is one of the central factors regulating cellular iron content and protecting the organism from iron toxicity.

We learn more about iron balance all the time. A recent study looked at the distribution of the ferritin protein within cells and the mechanisms underlying its secretion from the cell. They found iron rich extracellular ferritin strongly implying that ferritin is not merely a vessel for secure and available storage of iron within the cell, but also a key player in tissue and systemic iron distribution.

Always more to learn

Even if we learn more about our complex metabolism all the time, there is still a lot of uncertainty remaining. So the safe bet is still to eat a balanced diet all in moderation, be it iron intake or any other nutrient.

And by all means reduce any excessive sugar intake as long as you maintain your fibre consumption.


Please sir, can I have some more bananas

Heart3New evidence points to the importance of vascular calcification in hardening of the arteries, predicting adverse cardiovascular outcomes in several diseases, often with overlapping complications such as atherosclerosis, diabetes, and chronic kidney disease.

Clearly something to avoid so we need to know more about the underlying causes.

Vascular calcification was previously considered to be a passive, unregulated, and degenerative process, but has now been shown to be a highly regulated process of osteochondrogenic differentiation of vascular smooth muscle cells, the main cell type that determines the vascular tone, or simply blood pressure.

Sounds very complex, but just think hypertension and associated harmful effects.

So what’s happening here?

Well, epidemiological studies, but remember they can sometimes be suspect, have suggested a role for potassium. Low serum potassium levels have been linked to cardiovascular calcification and risks of chronic kidney disease and metabolic syndrome.

Even better we have further proof in that more reliable prospective cohort studies have shown that reduced potassium levels are associated with cardiovascular diseases such as hypertension and chronic heart failure. And providing an appropriate dietary potassium intake reduced the disease incidence.

So all good so far, but what is actually happening here?

Looking at the details

To better explain the findings, researchers at the University of Alabama explored the mechanism of vascular disease three ways: living mice were fed diets that varied in potassium, mouse artery cross-sections were studied in culture medium with varying concentrations of potassium, and mouse vascular smooth muscle cells were grown in a culture medium.

And they found that a reduction in the potassium concentration to the lower limit of the physiological range increased intracellular calcium, which in turn promoted vascular smooth muscle cell calcification in all models tested. Their findings provide molecular insights into the previously unappreciated regulation of vascular calcification and stiffness by low potassium intake and emphasise the need to consider dietary intake of potassium in the prevention of vascular complications of atherosclerosis, the researchers said.

And how do we do that?

Here is the good news

bananas_(Joey_Yee)We can eat more bananas. Bananas, and for that matter avocados, are foods that are rich in potassium. A banana a day (or two) might keep the doctor away and prevent hardening of the arteries.

But unfortunately that’s not the whole truth as one peeled banana weighing 120 g, good as it is, will only provide 422 mg of the European Food Safety Authority recommended 3,500 mg daily intake of dietary potassium. So you will have to eat eight bananas to be close to the recommended intake. That’s a lot.

What about if you add an avocado? Not more than another 485 mg I’m afraid. So more effort is needed.

Why not a single medium baked potato to get a whopping 941 mg of potassium or a medium baked sweet potato that has 542 mg of potassium. Or two watermelon wedges with 641 mg of potassium. A cup of frozen spinach provides a respectable 540 mg of potassium, while a cup of cooked and sliced beets add a further 518 mg.

Sounds like a lot of food, but you should know that actual food has proven to be much better than taking a shortcut by adding potassium supplements to your intake.

So stick to the food as best you can. The choice of food is yours.

Better stop now!

pillsComplementary medicines, to use a nomenclature that make them sound really important, or simply homeopathic medicines or in some instances dietary supplements, have been questioned before. And we and many others have repeatedly issued warnings of lack of evidence for claimed effects, illicit adulteration and the use of cheap fillers instead of the claimed substance. But it seems to no avail.

Agreed, some complementary medicines have actually been proven to work.  But what use is that when many of the products as sold do not match the dosages that have been clinically proven. And if they do it’s virtually impossible for consumers to distinguish the real from the fraudulent products.

When 500 complementary medicines out of 11,000 on the market in Australia were checked by the regulator, the Therapeutic Goods Administration, 400 of the products had compliance breaches.

Not particularly good.

The nail in the coffin

Traditional Chinese medicine is widely used all over the world as a form of complementary medicine for various indications and for improving general health. There is also an ever-growing market worldwide for a variety of health products, which contain herbal or other natural ingredients with claimed nutritional, physiological or health-promoting effects.

Such products are widely believed to be ‘natural’ and safe by many consumers, but some can pose severe danger to health in that undeclared compounds are lurking in the supposedly beneficial remedies. Adulterations commonly include prescription drugs, drug analogues and banned drugs.

Scientists in Hong Kong recently examined the files of 404 patients seeking medical attention due to moderate to severe reactions (including deaths) to the use of complementary medicines or other health products. Testing the implicated products  found more than 1200 illicit compounds. The 487 complementary medicines or health products consumed by the patients contained on average three adulterants with a maximum of an astonishing 17 undeclared adulterants.

The details of the findings

The six most common categories of adulterants detected were NSAIDs (17.7%), anorectics (15.3%), corticosteroids (13.8%), diuretics and laxatives (11.4%), oral anti-diabetic agents (10.0%) and erectile dysfunction drugs (6.0%). None of them declared on the packet.

Sibutramine, a slimming agent (anorectic) that has been withdrawn from the market due to its association with increased cardiovascular events and strokes, was the single most common adulterant identified.

Other banned drugs, such as phenolphthalein, fenfluramine, phenformin, phenylbutazone and phenacetin, were also not uncommonly detected in these adulterated complementary medicines. These drugs were usually withdrawn from the market owing to their higher toxicities and potential carcinogenicity.

Drug analogues, for which the chemical structures are substantially similar to those of the original compounds, were also occasionally identified. These drug analogues were probably added to the illicit products in an attempt to evade detection by regulatory authorities. The presumption that these analogues have similar pharmaceutical effects as the original drugs is unproven and, worse still, they may lead to adverse effects that are different or even more severe than those associated with the original compounds.

Psychosis, iatrogenic cushing syndrome, and hypoglycaemia were the three most frequently encountered adverse effects. Other effects included heart palpitations, renal impairment, abnormal thyroid function, damaged liver function and adrenal insufficiency.

Serious warning warranted

pharmacy_(Chis_de_Rham)Disguised as natural and safe products, some complementary medicines are clearly hazardous to the public with the overall area needing new and effective regulatory control.

The Hong Kong scientists stressed that the findings should serve as a serious warning to consumers and health professionals. If still tempted to use complementary medicines, as a short term solution at least make sure that they come from a reputable manufacturer.

In the longer term there is an urgent case for introducing mandatory testing of all complementary medicines both for purity and confirmation of claimed health effects.

In the meantime it might be best to save your money rather than risk your health in filling the pockets of shonky operators.

Happy beer drinkers!

beer_glass_(Tim_Dobson)I am not a big beer drinker but maybe it’s time to switch beverage. That is if you believe the new scientific findings that beer can lift your spirit. And that is not because of the alcohol content or good company. It is due to hordenine found in beer.

Let’s take a step back before you rush off to buy some beer.

I am sure though that you agree that some foods are more pleasurable than others. This effect is caused by the neurotransmitter dopamine — tempting foods stimulate the reward centre in the brain where the dopamine D2 receptor is located.

If not happy and smiling, pleasurable foods at least make you feel good. That is why we cannot stop eating when we have had enough. It is called hedonic hunger — the drive to eat for pleasure rather than to satisfy an actual biological need.

So which food components could be responsible for such an anomaly?

That’s what some German scientists at the Friedrich-Alexander-Universität Erlangen-Nürnberg decided to find out. And being German they examined as many as 13,000 food components to see if any of them could stimulate the reward centre in the brain and make people feel good.

Now that could be an enormous task to test in a laboratory setting but help was at hand. The team used a virtual screening approach which is often used in pharmaceutical research. This process analyses food components in a computer simulation rather than in the laboratory. Using computer simulations means that a large range of substances can be investigated.

The objective was to find those molecules that could fit into the dopamine D2 receptor — rather like finding the right key for a lock. They identified a more reasonable 17 of the original 13,000 as possible candidates to be analysed further in laboratory experiments. In the laboratory setting they tested which molecules actually initiated a positive response through the dopamine D2 receptor.

This might sound simple, but in reality the scientists used a range of different and complicated laboratory methods to narrow down the initial list of substances. To their slight surprise the most promising results were obtained for hordenine, a substance present in malted barley and beer.

Just like dopamine, hordenine stimulates the dopamine D2 receptor, however it uses a different signalling pathway. In contrast with dopamine, hordenine activates the receptor solely through G proteins, potentially leading to a more prolonged effect on the reward centre of the brain.

Hold on

Before you get too carried away, a word of warning. Although the findings are promising it is not yet clear if hordenine levels in beer are sufficient to have a significant effect on the reward centre.

But why should that spoil a good news story?

Watch out for milk thistle!

milkthistleMilk thistle is a flowering herb related to the daisy and ragweed family. It is native to Mediterranean countries. It’s ironic that milk thistle is used as a dietary supplement often taken to help protect the liver, while it can be contaminated by high levels of mycotoxins that are potentially harmful to the liver.

This has again been confirmed by a recent report by the European Food Safety Authority looking at the presence of the two mycotoxins T2 and HT2 in the diet. They found that milk thistle contained about five times higher levels of the two mycotoxins than any other product tested, with 220 µg/kg (T2) and 370 µg/kg (HT2) on average for milk thistle compared to oats with 40 µg/kg (T2) and 90 µg/kg, the second highest contaminated product.

And it is not the first time that a dietary supplement of some sort is at the top of the contamination table for a range of harmful compounds. And still people take them to improve their health. What’s wrong?

A little bit of background

Milk thistle is a plant also known as Chardon de Marie, Holy Thistle, Lady’s Thistle, Lait de Notre-Dame, Marian Thistle, Mariendistel, Mary Thistle, Shui Fei Ji, Silibinin, and many other names (in case you are looking for it).

Silymarin is the main active ingredient in milk thistle. Silymarin is both an anti-inflammatory and antioxidant. But it is unclear what benefits, if any, silymarin may have in the body.

Irrespective of clear proof of any beneficial effects, milk thistle has been used in alternative medicine as a possibly effective aid in treating heartburn, or seasonal allergy symptoms. Other uses not proven with research have included treatment for malaria, mushroom poisoning, spleen or gallbladder problems, menstrual problems, liver problems, and other conditions.

Milkthistle-supplementThere is not enough scientific evidence to say whether or not milk thistle can help liver problems. Some early research suggests milk thistle may aid people with alcohol-related liver disease. Other studies show no improvement in liver function in this group of people.

Some studies also show milk thistle may offer a possible benefit for people whose liver is damaged by industrial toxins, such as toluene and xylene.

However, more information is needed before it is possible to say that milk thistle actually benefits the liver.

Thus, let’s be clear that medicinal use of milk thistle compounds has not yet been supported by any regulatory authority. Still they are in common use all over the world.

Possible effect of mycotoxin contamination

Contamination of milk thistle with T2 and HT2 toxins have been reported from several parts of the world. T2 toxin and its deacetylated form HT2 toxin are members of the large family of trichothecenes. Fusarium species are the predominant moulds that invade cereal crops and produce T2 and HT2 under cool and moist conditions. Similar to most trichothecenes, T2 and HT2 not only inhibit protein synthesis and cell proliferation in plants, but also cause acute or chronic intoxication of humans and animals.

Toxic effects include growth retardation, myelotoxicity, hematotoxicity, and necrotic lesions on contact sites.

And this can be serious business.

Alimentary toxic aleukia (in simple terms a decrease in important white blood cells), a disease which is caused by trichothecenes, killed many thousands of USSR citizens in the Orenburg District in the 1940s. It was reported that the mortality rate was 10% of the entire population in that area.

During the 1970s it was proposed that the consumption of contaminated food was the cause of this mass poisoning. Because of World War II, harvesting of grains was delayed and food was scarce in Russia. This resulted in the consumption of grain that was contaminated with Fusarium moulds, which produced the two mycotoxins.

So what to do?

As for many dietary supplements it is probably best to stay away at least until any beneficial effect has been finally proven. There is also very little official oversight of the composition of any dietary supplement product. It has been proven again and again that they might contain several other compounds than what is declared on the label. Some that are themselves directly toxic.

So don’t gamble with your health!

Going nuts!

Sorry about the title. I couldn’t resist as going nuts seems to provide quite a few health benefits. Nothing completely new, but recently published scientific findings strengthen the case for the benefits of eating nuts. All in moderation of course.

The week started with news that eating almonds on a regular basis may help boost levels of the good (high-density lipoprotein or HDL) cholesterol while also improving the way cholesterol is removed from the body.

And it ended with news of a new brain imaging study showing that consuming walnuts activates an area in the brain associated with regulating hunger and food cravings, thus discouraging overeating by promoting feelings of fullness.

The goodness of almonds

almonds2It has previously been shown that a diet that includes almonds lowers the bad (low-density lipoprotein or LDL) cholesterol, which is a major risk factor for heart disease. But not as much was known about how almonds affect HDL cholesterol, which helps lower the risk of heart disease.

HDL is like a garbage bag that slowly gets bigger and more spherical as it gathers cholesterol molecules from cells and tissues before depositing them in the liver to be broken down and excreted.

The researchers wanted to see if almonds could not just increase the levels but also improve the function of HDL cholesterol.

In a clever trial researchers found that HDL cholesterol levels and functionality improved when participants received 43 grams – about a handful – of almonds a day compared to when the same participants ate a banana muffin instead.

This should reduce the risk of heart disease and in addition almonds also provide a dose of good fats, vitamin E and fibre that might improve health, with the caveat that the research was supported by the Almond Board of California.

The goodness of walnuts

walnuts2Walnuts are not far behind almonds as they too are packed with nutrients linked to better health. Not being enough, it was also previously known that people reported feeling fuller after eating walnuts although not necessarily why.

Now to determine exactly how walnuts stop food cravings scientists used functional magnetic resonance imaging (fMRI) to observe how walnuts could change activity in the brain.

During one five-day session, volunteers consumed daily smoothies containing 48 grams of walnuts and during a separate session they received a walnut-free but nutritionally comparable placebo smoothie, flavoured to taste exactly the same as the walnut-containing smoothie. The order of the two sessions was random.

As in previous observational studies, participants reported feeling less hungry during the week they consumed walnut-containing smoothies than during the week they were given the placebo smoothies. And fMRI tests administered on the fifth day of the experiment revealed for the first time details of the neurocognitive impact these nuts have on the brain.

When participants were shown pictures of highly desirable foods, fMRI imaging revealed increased activity in a part of the brain called the right insula after participants had consumed the five-day walnut-rich diet compared to when they had not.

As this area of the insula is likely involved in cognitive control and salience, it meant that participants were paying more attention to food choices and selecting the less desirable but healthier options over the highly desirable but less healthy options.

But again you should know that this study was supported by commercial interest, this time the California Walnut Commission.

Be careful with the calories

So good news on all fronts but how to handle this information? Binge on almonds and walnuts every day?

Well, it may pay off to be a bit careful with the calorie intake as eating a handful each of both almonds and walnuts in the same day would equate to eating two banana muffins daily. And not many nutritionists would recommend that.

Vegemite in the spotlight

At it again, are they? That is public health scientists trying to find correlations between individual food items and a positive or negative health impact. Often negative effects unless the research is sponsored by the food manufacturing company.

In this case we don’t know as the research doesn’t seem to be published yet, but the findings were anyway released to the press. And to be fair they got a lot of publicity, at least in Australia, so good on them.

We are talking about yeast-based spreads.


Vegemite is the yeast-based spread of choice in Australia. It is a thick, black food spread made from leftover brewers’ yeast extract, thus rich in B vitamins. It is supplemented with various vegetables and spices to make it more appetising. It was developed in Melbourne, Victoria and has been around commercially since 1923. It is salty, slightly bitter, malty with a taste of beef bouillon. Vegemite is similar to the British, New Zealand and South African Marmite, the German Vitam-R and the Swiss Cenovis. As it is so popular in Australia there are several competing products like Promite, MightyMite, AussieMite and OzEmite.

A market survey from 2014 found that an astonishing 7,550,000 Australians ate one of the iconic yeast-based spreads once a week.

And it might be good for you

Now new research has found beneficial health effects in people who eat the vitamin B-containing spreads.

But there are several caveats. The study involved only 520 people split across three countries: Australia, New Zealand and the UK. It was conducted over the internet with the normal vagaries of such studies. The survey participants were asked how often they consumed yeast-based spreads, which products, and how long they’ve eaten them for.

Importantly, the survey also asked participants about their dietary and lifestyle habits as well as their current mental and emotional state, information not easy to capture accurately.

And the press release didn’t mention how the detailed consumption information was handled in relation to the beneficial effects.

But here is the interesting part.


Anyway, believe it or not, people who ate yeast-based spreads expressed lower levels of anxiety and stress compared to those who ate none, and even more astonishingly those who consumed spreads containing B12 were even less stressed and anxious than those who used the other brands.

As each spread varied in levels of B vitamins – including B1, B2, B3, B9 and B12 – it is important to note the finding that those containing B12, like Marmite, MightyMite, AussieMite and the newer salt-reduced Vegemite, but not the original Vegemite, were most effective.

Is this a joke or what?

Well, even the scientists advised that the survey results do not prove that the spread improved mental health as it may be something else going on in the lives of the survey participants.

So true.

They certainly stressed that they would like to investigate their findings further by carrying out randomised control trials with yeast spreads to see if they can improve depression and anxiety in people.

Not complete pie in the sky science

Actually there is some basis for the hypothesis proposed by the scientists. B vitamins are essential in keeping our bodies energised and in regulating the nervous system. A previous Australian study was suggestive of significant decreases in the experience of workplace stress after 90 day supplementation with a B multivitamin.

After individual differences in personality and work demands were statistically controlled, the vitamin B treatment groups reported significantly lower personal strain and a reduction in confusion and depressed/dejected mood, but this did not cover all mood swings.

And there are a few other studies with similar results.

So what can we learn from the findings?


It is clear that yeast extracts contain some of the world’s richest sources of B vitamins. And it is also clear that B vitamins are essential in assisting some of our important bodily functions.

Even so, I have to say that I prefer not to belong to the “happy little Vegemite” group, as the advertising jingle promotes, as I cannot stand the taste.

And there are many other sources of B vitamins. They can be found naturally in animal products including fish, poultry, meat, eggs and dairy, as well as whole grains, walnuts, soy and rice milk.


I’d love to believe

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Red wine benefits?

I’d love to believe that the resveratrol in red wine possesses a range of health benefits including anti-cancer effects, anti-inflammatory effects, cardiovascular benefits, anti-diabetes potential and protection against Alzheimer’s. Thus good for all adult ages. A glass of wine a day might keep the doctor away.

But it might be wishful thinking. It is true that resveratrol can inhibit growth of cancer cells in a culture and in some animal models, but it is not known whether it can prevent cancer in humans. It has increased the lifespans of yeast, worms, fruit flies, fish, and mice fed a high-calorie diet, but again this has not been shown in humans. So the brutal truth is probably that the amount of resveratrol in red wine is too small to have any measurable beneficial effects in humans.

But we can still believe!


Whisky benefits?

I’d love to believe that the ellagic acid content of whisky actually can reduce oxidative stress. Ellagic acid has been shown to have antiproliferative and antioxidant properties in a number of in vitro and small-animal models. It may directly inhibit the DNA binding of certain carcinogens, and it has a chemoprotective effect in cellular models.

But again it might be too good to be true. Ellagic acid has been marketed as a dietary supplement with a range of claimed benefits against cancer, heart disease, and other medical problems. In 2008, the U.S. Food and Drug Administration called it a fake cancer ‘cure’ consumers should avoid. So not much luck there.

But we can still believe!

It might actually be premature to give up red wine and whisky completely. As antioxidants, like resveratrol and ellagic acid, are additive any contribution is useful. Complement the spirits with plenty of berries, dark green vegetables and nuts and you will not go wrong. Red wine and whisky will be outdone on the health front, but so what.

But there is more…


Red chilli pepper benefits?

I’d also very much love to believe the latest reports that consumption of hot red chilli peppers can reduce deaths due to heart disease or stroke. Going back for centuries, peppers and spices have been thought to be beneficial in the treatment of many diseases. A new study using National Health and Nutritional Examination Survey (NHANES) III data collected from more than 16,000 Americans who were followed for up to 23 years, found that hot red chilli pepper consumption decreased mortality by 13%.

But unfortunately the findings, widely published by the popular press, are based solely on epidemiological data. Exploring epidemiological data, even if prospective in nature, is fraught with obstacles. The authors themselves point out that given the observational nature of the investigation, causality can only be suggested, not confirmed.

However, on the bright side there is some support for the findings in a theory that capsaicin in chilli peppers can influence cellular and molecular mechanisms that prevent obesity and modulate coronary blood flow, and also possesses antimicrobial properties that may alter the gut microbiota.

In a sign of our desperate need to find some beneficial news the popular press was inundated by citations of the positive findings. Some examples:

  • “Can eating spicy food lead to a longer life? Chili peppers could be the secret” says National Post.
  • “Spicy food could be the secret to a healthy heart and a longer life, says new study” says The Telegraph.
  • “This Is Your Body On Spicy Foods” says The Huffington Post.
  • “Eat Peppers, Live Longer?” says New York Times.
  • “Red hot chilli peppers: the way to a longer life?” says The Sydney Morning Herald.

If you’re on to a good thing the press will pick it up. Doesn’t mean it’s true though. But we can still believe!

Magical dietary fibres


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 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.

More dietary fibre


Beneficial bugs (Photo: NIAID)

Be kind to your intestinal flora and it will be kind to you in return. We are talking about the microbiome, the trillions of bugs in your large intestine living in symbiosis with you.

We have written about the microbiome before. All the good deeds the bugs can do if you just feed them the right raw material. And dietary fibre is the ideal food source to support the needs of the beneficial bugs.

The fibre gap

Insufficient nutrients for our gut bacteria have been linked to a loss of certain beneficial bacterial species in western societies and are likely impacting our immunological and metabolic health. Most westerners consume only half of the amount of dietary fibre recommended by dietary guidelines. Nutritionists refer to this as the “fibre gap,” and it is a problem because dietary fibre is the primary source of nutrition accessible to gut bacteria in humans.

Scientists have long promoted the importance of strategically increasing dietary fibre intake as one path forward in regaining gut microbial biodiversity. Although this advice is far from new, the now proven depletion of the microbiome with a fibre deficient diet adds a new perspective to the western diet that we are currently eating.

Comparative studies between rural communities from Africa and South America and industrialised western communities from Europe and North America have revealed specific adaptations of their microbiomes to their respective lifestyles. These adaptations include higher biodiversity and enrichment of Bacteroidetes and Actinobacteria in rural communities, and an overall reduction in microbial diversity and stability in western populations.

Restoring fibre intake can have immediate effects

Some scientists are concerned that a dramatic shift away from a diet similar to the one under which the human-microbiome symbiosis evolved is a key factor in the rise of non-communicable disorders like obesity. There is also a lot of epidemiological evidence that food products containing dietary fibre can help prevent the development of colon cancer and reduce the incidence of coronary heart disease.

It is clear that people living in non-industrialised societies have an average intake of fibre that is much higher than the low norms of western societies. In an experiment scientists compared the effects of a traditional South-African and a modern American diet.  Twenty South Africans gave up their corn porridge and vegetable stews for burgers and fries. And 20 Pittsburghians sacrificed fast food staples for the low-fat, high-fiber fare that South Africans traditionally eat that contained 55 grams of daily dietary fibre. Surprisingly, the Americans had improved markers for colon cancer already within two weeks, while the South Africans showed the opposite effects.

The good news is the finding that changes in the microbiome are largely reversible within a single generation if the fibre intake is increased. However, there are also bad news. With several generations on a fibre deficient diet a progressive loss of diversity is seen, which is not recoverable. So your children and children’s children will lack some of the beneficial microbial species, indicating that extinctions can occur in only a few generations.

Convinced yet?


Eat more fibre-rich food

It is recommended to eat 25-30 grams of dietary fibres a day from a variety of foods rich in both insoluble and soluble fibre.

Foods higher in insoluble fibre include:

  • whole grain breads and cereals
  • the outer skins of fruit and vegetables
  • nuts and seeds
  • raw lentil, kidney beans and chickpeas

Foods higher in soluble fibre include:

  • fruits and vegetables
  • dried beans and lentils
  • oats

To help meet your daily dietary fibre requirements look at the below table from the Dietitians Association of Australia:

Food Fibre content
3/4 cup whole grain breakfast  cereal  4.5g
2 slices wholemeal bread 4.5g
1 apple (with skin) and 1 orange  5.5g
2 cups mixed raw vegetables 10g
1/4 cup legumes eg. baked beans 3g
Total 27.5g