The fight is on over sugar

ScientistIt is difficult even for experienced scientists to agree on the interpretation of their findings. Add to that external research funding linked to commercial interests and it is even more difficult to know what to believe.

A case in point. If you thought excessive sugar intake is the root of the evil obesity epidemic you might have to think again.

Or not….

Sugar advice questioned

There has been a scathing attack on global health advice to eat less sugar. Through industry proxies, a scientific review now claims that warnings to cut sugar are based on weak evidence and cannot be trusted.

The review identified 9 guidelines that offered 12 recommendations, all indicating a suggested decrease in the consumption of foods containing nonintrinsic sugars (that is added sugar to you and me). The recommendations were based on various health concerns, including nutrient displacement, dental caries, and weight gain. However, the reviewers claimed that no guideline met criteria for trustworthy recommendations and were all based on low-quality evidence.

The review was paid for by the International Life Sciences Institute, a scientific group funded by multinational food and agrochemical companies.

Tainted from the beginning. When will industry ever learn.

The review findings immediately questioned

Predictably, the review quickly received sharp criticism from public health experts. It was but the latest effort of the food industry to influence global nutrition advice by supporting prominent academics questioning the role of sugary food and beverages in causing obesity and other health problems.

The review was seen as an attempt to undermine sugar guidelines from the World Health Organization (WHO) to consume fewer products with added sugar, such as soft drinks, candy and sweetened cereals. It is a classic example of how industry funding is used to influence opinion.

To be fair to the review team, they wanted their results to be used to promote improvement in the development of trustworthy guidelines on sugar intake. They also emphasised that the review findings should not be used to justify higher intake of sugary foods and beverages.

Still, nutrition experts say that the review team ignored the hundreds of randomised controlled trials that have documented the harms of sugar. There are strong scientific evidence that sugar contribute to adverse health conditions like weight gain and Type 2 diabetes. The view is that the review team ignored the real data, created false scores, and somehow got through a peer review system difficult to understand from a reputable journal like Annals of Internal Medicine.

The WHO contrary point of view

soda

So until we have the general scientific opinion swinging over to supporting sugar, it is clearly best to stick to the WHO recommendations.

A WHO guideline of 2015 recommends that adults and children reduce their daily intake of free sugars to less than 10% of their total energy intake. WHO also believes that a further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits.

Free sugars refer to monosaccharides (such as glucose, fructose) and disaccharides (such as sucrose or table sugar) added to foods and drinks by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates. But the guideline does not refer to the sugars in fresh fruits and vegetables, and sugars naturally present in milk.

Contrary to the above review findings, WHO states that they have solid evidence that keeping intake of free sugars to less than 10% of total energy intake reduces the risk of overweight, obesity and tooth decay. Based on the quality of supporting evidence, these recommendations are ranked by WHO as “strong”.

So there you have it. And if you embark on reducing your sugar intake remember that much of the sugars consumed today are “hidden” in processed foods that are not usually seen as sweets.

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Too much fat or too much sugar

Added sugar cause more problem than high fat (Photo: Health Gauge)

Replacing fat with sugar is a bad choice (Photo: Health Gauge).

New research findings justifies another look at this topic we have covered before, but this is not easy with very polarised views. It used to be simple in the past. What’s now considered flawed research stated that fat, particularly saturated fat, was bad for our health. It increased cholesterol levels and caused heart disease with early death. Low-fat diets were in vogue and industry produced plenty of low-fat alternatives for the proselytes.

Unfortunately, industry substituted fat with sugar and that didn’t help the situation much. Actually, it now seems to have made what was considered a bad situation even worse.

Fight between old and new science

In a previous blog I put my toe into the sugar debate, an issue that has recently turned nutrition on its head. Now overindulgence in sugar is the culprit behind several diseases and increased mortality. So in the one corner we have the old die-hard supporters of the low-fat diet, while in the other corner we have the fresh newcomers daring to promote a low-carb high-fat diet.

Although the low-fat supporters have lost considerable ground the umpire seems to still be sitting on the fence. The 2015-2020 Dietary Guidelines for Americans target both saturated fats and added sugars as nutrients to limit and seem to give them equal weight in their advice:

  • Consume less than 10% of calories per day from added sugars, and also
  • Consume less than 10% of calories per day from saturated fats.

Let’s just pause for a moment to consider this new advice. The energy stored in our food is measured in terms of calories. Technically, one calorie is the amount of energy required to raise the temperature of 1 gram of water 1º Celsius. However, in the food area a calorie is actually 1000 technical calories. Although the technical calorie unit is part of the metric system, it has been superseded in the International System of Units by the joule and used in some countries as the new energy measure. A food calorie is approximately 4.2 kilojoules. Confused, I thought so. So for convenience let’s stick to the common use of calorie in the food area and forget that technically it is actually kilocalories.

Now to be clear, sugar contains less than 4 calories, whilst fat contains 9 calories per gram. Thus, according to the above recommendations you could consume double the amount of added sugar compared to saturated fat to keep within the given proportion of energy allocated to each of the two nutrients. So although the recommendation looks evenhanded in reality it is not.

New studies support the low-carb camp

New scientific findings

New scientific findings give further support to the low-carb camp.

Back to the science. With the tables turning, low-fat diets are out and high-fat diets are very much in. Since the eat-less-saturated-fat advice has been around for decades, there should be proof around either way you would think. However, it took quite some time to disprove the fat hypothesis since it was considered heresy.

This has changed and a new article cites several meta-analyses of randomised controlled trials that did not find a connection between saturated fats and heart disease or overall death rates.

But it goes further with low-carb comparisons. A recent study suggested that low-fat diets might not be the way to go after placing about 150 adults on either a low-carb or a low-fat diet for a year. Participants on the low-carb diet lost more weight and lowered their risk for heart disease more than participants who followed a low-fat diet.

Another study involved 17 people at risk for heart disease and diabetes. They were put on a low-carb, high-fat diet for three weeks. Then, they turned the table and increased carb intake while reducing total fat and saturated fat intake every three weeks for 18 weeks, keeping total caloric intake the same. The more carbs and less fat in the diet resulted in an increase in markers linked to obesity, type 2 diabetes, and heart disease. I know, a very small group of people, but anyway.

So is the fight over?

No, we are still waiting for the knock-out blow. Life is never that simple.

As for saturated fats, these fats are a diverse class of compounds. Some saturated fats elevate bad cholesterol, others have no effect, and some actually increase good cholesterol. Fats in foods are always a mixture. While some foods high in saturated fats, such as processed meats, might be connected to heart disease, other foods high in saturated fat such as dairy have no such effect. And there is also the supposition that some polyunsaturated fats might induce inflammation that in turn can influence the heart disease rate.

And similarly to fats, not all carbs are equal. The monosaccharide, fructose, and the disaccharide sucrose, common table sugar, with half fructose (together with glucose), produce greater degrees of metabolic abnormalities than does glucose alone found in long chains of starch in certain foods and cellulose in plant walls.

If you need to lose weight science is pretty clear. If you eat too little fat, your metabolism won’t be as efficient and will create some waste because of an excess of carbs and/or protein. A slower metabolism and a higher load of waste will interfere with weight loss. On the other hand, high-fat food dampens appetite and can help you eat less and thus lose weight.

Sugar can be fattening indirectly by causing you to eat more. Eating too much sugar will encourage insulin production. If you produce too much insulin it actually causes blood sugar to dip and you feel tired. As you need an energy boost you eat more, and you tend to give in to cravings for more sugar. Of course, that only makes the whole cycle happen again.

But we don’t eat fat or carbohydrates in isolation, we eat them in the form of complex foods with a lot of other necessary components. If you forget weight loss and just want to maintain a healthy diet there is room for good forms of both fat and carbohydrates. With fat you get important fat-soluble vitamins and essential fatty acids, and with complex carbohydrate foods you get minerals, water-soluble vitamins and antioxidants like flavonoids.

What about everything in moderation?

Find the right balance for healthy eating (Photo: Mauro Cateb).

Find the right balance for healthy eating (Photo: Mauro Cateb).

We have said it before, why not everything in moderation as the saying goes. Or did go!

Even that has now been criticised as being too vague and difficult to measure. ‘There are no good or bad foods,” and “all foods can fit into a healthy diet” are variations on the moderation theme. But what exactly is moderation? A new study found that definitions of moderate consumption were related to personal consumption behaviours. Results suggest that the endorsement of moderation messages allows for a wide range of interpretations of moderate consumption.

Healthy eating is about finding a balance between two extremes – deprivation and overindulgence. It is about adhering to strategies and habits that can be maintained long term as part of a lifestyle to avoid a yoyo effect between these extremes.

Call it what you like as long as you don’t give in to your ghrelin urge too often. An occasional binge can be justified to keep you happy. That’s what life is all about, isn’t it?

Lead – up to no good

car-exhaust

Lead in petrol an earlier culprit in lead poisoning.

Lead has been used for thousands of years because it is widespread, easy to extract, and easy to work with. It is highly malleable and easily meltable. Equally, lead poisoning has been documented since ancient Rome, ancient Greece and ancient China. It is thus clear that, ingested or inhaled, lead is poisonous to animals and humans. Still we were foolish enough to add it to petrol starting in the 1920s and use lead pigments particularly in white but also in yellow, orange, and red paint to spread its occurrence even further.

We have lived with the consequences ever since. Lead poisoning typically results from ingestion of food or water contaminated with lead, but may also occur after accidental ingestion of contaminated soil, dust, or lead-based paint. It is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders. Lead has been shown many times to permanently reduce the cognitive capacity of children at extremely low levels of exposure. Lead exposure in early childhood has also been linked to violent crime.

But there is more

As if that was not enough, new research has shown that early life exposure can alter the composition of the gut microbiota (remember one of my favourite topics), increasing the chances for obesity in adulthood. So far at least in mice. Lead was added to the drinking water of female mice prior to breeding through nursing their young. The lead levels used  were designed to be within past and present human population exposure levels. Thus the lowest dose used of 5 µg/dL is the same as the current US blood lead action level, while the higher dose mirrored exposure levels during the 1960s and 1970s to be able to evaluate both current and historically relevant lead levels.

Once weaned, the offspring were raised to adulthood without additional exposure, and then tested for lead effects acquired from their mothers. The guts of both males and females exposed to lead had all of the similar complexity in microbiota as those not exposed. The differences were in the balance of the different groups of microorganisms. Due to differences in their gut microbiota, adult male mice exposed to lead during gestation and lactation were 11 percent heavier than those not exposed. But not females, although the researchers speculate that females might have shown effects on obesity if they had followed them longer.

Although improving, it is not over yet

fatmouse

Lead exposure linked to obesity in mice.

So now we have obesity added to the long list of potential harm caused by lead contamination. Fortunately, by the mid-1980s, a significant shift in lead end-use patterns had taken place with lead use phased out from petrol in many countries and banned from paint, but still remaining in some grades of aviation fuel, and in some developing countries.

Although the situation has improved, it is not over yet. Lead may be introduced to foods from the use of lead containing pottery or lead crystalware. Another source is water from lead containing pipes. And wild game that has been shot with lead pellets. Not to forget some odd Chinese herbs found to contain high lead levels.

So vigilance is still needed.

Iron – friend or foe?

red blood cells

Iron is necessary for the red blood cell supply.

Well the answer to the question is both, but that might be a surprise to you since iron has a clearly positive reputation among the general public. Iron is a mineral and a friend in that it plays a key role in the making of red blood cells. Too little iron may lead to anaemia, a low level of red blood cells. Anaemia can cause fatigue and other symptoms. Too little iron can also have disastrous effects on memory, growth, and overall physical health. It is often said that the more iron, the better. But that is actually not true since excess iron can be a foe. Let me explain in more detail.

Too much iron

Large amounts of ingested iron can cause excessive levels of iron in the blood.  There is also the issue of haemochromatosis, a genetic disorder where affected people absorb too much iron from a perfectly normal diet. Excess iron is stored in the body. Over time this leads to iron overload.

The problem is that although we have mechanisms in place for regulating iron absorption, men of any age and post-menopausal women have no mechanisms that can get rid of excess iron, except by giving blood. That reminds me of medieval blood letting as a primitive “cure” for most diseases. There might actually be some benefits to such treatments.

Iron toxicity

Campylobacter

Bugs just love excess iron.

Iron toxicity occurs when there is free iron in the cell, which happens when iron levels exceed the capacity of transferrin to bind the iron. Damage to the cells of the gastrointestinal tract can also prevent them from regulating iron absorption leading to further increases in blood levels.

High blood levels of free ferrous iron react with peroxides to produce free radicals, which are highly reactive and can damage DNA, proteins, lipids, and other cellular components. Observational studies have tracked such changes to the development of  type 2 diabetes, heart disease, insulin resistance, inflammation, Alzheimer’s disease, hypertension, fatty liver, hypothyroidism, and arthritis. A daunting list of diseases connected to excess body stores of iron.

There is also the issue of the purported connection between red meat consumption and the development of colorectal cancer. One of the theories supporting this connection blame the high iron content of red meat.

Complicating things further, this is heaven for disease-causing bacteria. Like all living beings, bacteria need iron to survive and multiply. Excess iron promotes their growth and capacity to make you sick.

So what to do?

Let’s first look at iron intake. You can certainly get enough iron from food. Iron absorption is best (15-18%) from foods that contain haem iron. Red meat, seafood and poultry are the best sources of haem iron. Iron absorption from foods that contain non-haem iron is much lower (<5%). Non-haem iron is predominantly found in plant foods such as cereals, vegetables, legumes and nuts.

In case of a deficient diet it is also possible to use iron supplements to improve iron status. Iron supplements are often used to treat anaemia caused by pregnancy, heavy menstrual periods, kidney disease and chemotherapy. Iron supplements are commonly recommended for infants and toddlers, teenage girls, and women who are pregnant or of childbearing age to help prevent anaemia.

But if you actually need less iron?

coffee3

A cup of coffee after dinner can reduce iron absorption.

Phytonutrients like polyphenols, flavanols and other plant-derived antioxidant compounds inhibit iron absorption. They can be found in apples, onions, grapes, many other plant foods, and in most colourful spices and herbs.

Even low levels of phytates have a strong inhibitory effect on iron absorption. Phytates can be found in walnuts, almonds, sesame, dried beans, lentils, peas, cereals and wholegrain.

A cup of coffee after dinner is particularly good at inhibiting iron absorption with instant coffee the most effective. Tea might even be better. Tannins in coffee and tea bind the iron and prohibit absorption.

But there is more help at hand in a piece of cheese after dinner. The calcium it contains is a potent inhibitor of iron absorption. More than that, calcium reduces any carcinogenic interactions between haem iron and colonic cells.

If you’re going to drink alcohol, make it red wine and lean toward lower-alcohol wines. Its polyphenols inhibit iron absorption, while straight ethanol enhances iron absorption.

And if that is not enough you might try some ancient blood letting or in simple terms become a blood donor.

Can honey make you sick?

honey_(Hillary_Stein)

The safety of honey questioned (Photo: Hillary Stein)

Is the world mad when Irish scientists focus their attention on Australian honey and find high levels of pyrrolizidine alkaloids? And the results are sensationalised by the Australian press a year later, talk about a slow response! Headlines in January 2016 proclaimed that “Australian honey could make us sick” and the article stated that “Australian honeys are the most contaminated in the world with natural poisons linked to chronic disease including cancer”. If that didn’t frighten you, what would?

And truely, pyrrolizidine alkaloids are natural toxins linked to chronic disease including cancer. Typically the compounds affect the liver and in some cases the lungs causing serious illness. Animal experiments have also shown that certain pyrrolizidine alkaloids are genotoxic carcinogens, the worst of the worst of toxins.

So what are they?

Pyrrolizidine alkaloids are produced as a protection against herbivores by about 6,000 plant species, representing 3% of all flowering plants, most of which are weeds. There is a great variety of compounds with more than 500 different pyrrolizidine alkaloids known to date. Besides in honey, pyrrolizidine alkaloids in food have been detected in products of plant origin, for example, in herbal teas and supplements, cereals, and salads. Cases of elevated contamination in wheat are known to have occurred in Afghanistan associated with illness and similarly contaminated salad in Germany.

To be fair to the Irish, the study was all about developing better analytical methods for detecting multiple pyrrolizidine alkaloids and the scientists probably selected Australian honey to be certain of having positive samples. They could as well have selected South American samples also known for containing high levels of pyrrolizidine alkaloids.

Nevertheless, their results showed that 41 of the 59 honey samples were contaminated by pyrrolizidine alkaloids with a mean total sum of 153 µg/kg. This is on average four times more pyrrolizidine alkaloids than in European honeys and is quite high as an average level. Echimidine and lycopsamine were most common and found in 76% and 88%, respectively, of the positive samples. The scientists also attempted to calculate possible average daily exposure based on the results and found that adults could have an exposure of 0.051 µg/kg bodyweight per day and children 0.204 µg/kg bodyweight per day of pyrrolizidine alkaloids.

What does it mean?

It is debatable if all pyrrolizidine alkaloids should be treated equally when considering their toxicity due to their expected cumulative effects or if some of the compounds could be considered to be less toxic.

laboratory

Scientists cannot agree on how to assess safety of honey.

Conveniently the Australian authority, Food Standards Australia New Zealand, considers that echimidine is less toxic and used a Tolerable Daily Intake approach in establishing a safe level of exposure of 1 µg/kg bodyweight per day. This was calculated by applying an uncertainty factor of 10 to what was considered to be a human no-observed-effect level of 10 µg/kg bodyweight per day for liver failure due to veno-occlusive disease. But carcinogenic effects were not considered. Using this approach the Irish exposure estimates are well within safe limits.

Not so says a number of national and international organisations like the World Health Organization International Programme on Chemical Safety, the Dutch Rijksinstituut voor Volksgezondheid en Milieu, the UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, the German Bundesinstitut für Risikobewertung, and the CONTAM Panel of the European Food Safety Authority. They have all concluded that 1,2-unsaturated pyrrolizidine alkaloids may act as genotoxic carcinogens in humans (that is they may cause cancer and damage DNA, the genetic material of cells).

The safety of genotoxic carcinogens should be evaluated using the Margin of Exposure approach and not the Tolerable Daily Intake approach. A benchmark dose lower confidence limit for a 10% excess cancer risk (BMDL10) of 70 μg/kg bodyweight per day for induction of liver haemangiosarcomas by lasiocarpine in male rats was calculated as the reference point for comparison with the estimated dietary exposure. As a Margin of Exposure of 10,000 or higher, based on a BMDL10 from an animal study, is considered to be of low concern from a public health point of view, exposure to 0.007 µg/kg bodyweight per day or less of pyrrolizidine alkaloids would not be a worry. But the Irish presented much higher exposure estimates.

What margin is safe?

The different interpretations of what is a safe exposure to pyrrolizidine alkaloids is confusing to scientists and the public alike. Honey consumption has a long and varied history as a remedy for several health afflictions. Although, due partly to low numbers and questionable quality of human studies, some of the suggested health benefits of honey have been difficult to prove scientifically. Nevertheless, the public perception is that honey is a wholesome and natural product beneficial to health and a tastier alternative to refined sugar. There is a small committed group of consumers that regularly consume relatively large amounts of honey. So the findings of pyrrolizidine alkaloid contamination is disturbing.

Patersons

Paterson’s curse is a common source of pyrrolizidine alkaloids in honey.

However, there are som alleviating factors to reassure honey consumers. The presence in honey of lasiocarpine used to calculate the BMDL10 is rare and most other pyrrolizidine alkaloids are at least a magnitude less toxic. This could raise the level of exposure of no concern to 0.07 µg/kg bodyweight per day. Also retail honeys are often mixed from several sources to reduce the overall level of pyrrolizidine alkaloids in the consumer-ready product. And finally the Australian honey industry is claiming that they have reduced access of bees to Paterson’s curse, a main source of pyrrolizidine alkaloids in Australian honey. But the future will tell if that is right.

So some caution is justified for regular honey consumers. Vary your source of honey to limit exposure and hopefully you will be fine. For now.

 

The fight for your attention

Cravings for a doughnut might be blamed on the microbiome (Photo: Makoto Satsukawa)

Cravings for a doughnut might be blamed on the microbiome (Photo: Makoto Satsukawa)

You’re working along doing your usual stuff and suddenly you feel a hunger pang. And you don’t just feel hungry, you crave fatty food. If you had a Krispy Kreme doughnut ready you would gulp it down. But fortunately there is none within reach. There are conflicting signals and you change your mind. Now you have a craving for sugar and you stretch for the Coke. You know you shouldn’t but you still do it. What’s happening here?

Your microbiome at work

You remember the microbiome we have written about in previous blogs, the 100 trillion bacteria in your gut that outnumber your own cells about 100-fold? They help breaking down your food, fighting off infections and nurturing your immune system. It’s a lovely, invisible garden that play a crucial role in your well-being. However, even if it sounds like science fiction, it seems they are not content with limiting their activity to the gut, but may very well affect both your cravings and mood to get you to eat what they want.

Bacterial species vary in the nutrients they need. What that means is that some for instance prefer fat, and others sugar. The creepy part is that they not only vie with each other for the food they need to try to retain a niche within the digestive tract, they also try to make sure that you select the food they need. Different species of microbes thrive on different kinds of food. If they can prompt us to eat more of the food they depend on, they can multiply.

Researchers in reviewing the recent scientific literature concluded that microbes in the microbiome influence human eating behaviour and dietary choice to favour consumption of the particular nutrients they grow best on, rather than simply passively living off whatever nutrients you choose to send their way. There is a diversity of interests represented in the microbiome, some aligned with our own dietary goals, and others not. Of course it makes sense for them, but the question is how they have the means to influence what you eat.

Signalling systems at work

While it is unclear exactly how this occurs, the research team believes this diverse community of microbes may influence our decisions by releasing signaling molecules into our gut. This alone might not send any red flags, but because the gut is linked to the immune system, the endocrine system and the nervous system, those signals could influence your physiologic and even your own behavioural responses.

Research suggests that gut bacteria may be affecting your eating decisions in part by acting through the vagus nerve, which connects 100 million nerve cells from the digestive tract to the base of the brain. Microbes have the capacity to alter the neural signals in the vagus nerve, changing taste receptors, producing toxins to make you feel bad, and releasing chemical rewards to make you feel good.

Who is the puppet master?

Who is the puppet master? (Photo: Luc De Leeuw)

Who is the puppet master? (Photo: Luc De Leeuw)

Fortunately, it’s not a one-way street. In turn your own diet choice will have a huge impact on the microbial population in your gut. It’s a whole ecosystem, and it’s evolving on the time scale of minutes. You can influence the composition of the microbiome by deliberately change what you eat, with measurable changes in the microbiome within 24 hours of a diet change.

This may be accomplished through food and supplement choices, by ingesting specific bacterial species in the form of probiotics, or by killing targeted species with antibiotics. Because the microbiome is easily manipulated by prebiotics, probiotics, antibiotics, fecal transplants, and dietary changes, altering our microbiota might offer a possible approach to otherwise difficult problems of obesity and unhealthy eating. Optimising the balance of power among bacterial species in our gut might allow us to fight obesity and live more healthier lives.

We are only beginning to scratch the surface of the importance of the microbiome for human health. Targeting the microbiome could open up possibilities for preventing a variety of diseases from obesity and diabetes to cancers of the digestive tract. Although it is early days, it might pay off to attempt to be in charge of what you eat, now when you know the sneaky impact of your own bugs. Try to be your own puppet master.

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Increase your nut consumption

A heart healthy diet (Photo:  Gabriela Camerotti)

A heart healthy diet with nuts (Photo: Gabriela Camerotti)

Most nuts contain several healthy ingredients that, among other things, can be good for your heart. Hand on heart, how often do you eat nuts? And don’t count the salty or chocolate coated nuts. Apart from those, the type of nut you eat isn’t that important, although some nuts have more heart-healthy nutrients and beneficial fats than do others. Eating nuts can lower the low-density lipoprotein (LDL, or “bad”) cholesterol levels in blood. They may reduce the risk of developing blood clots that can cause a fatal heart attack. Nuts also appear to improve the health of the lining of the arteries. All good news.

Besides being packed with protein, most nuts contain both beneficial monounsaturated and polyunsaturated fats. Nuts are one of the best plant-based sources of omega-3 fatty acids. All nuts contain fibre. Nuts are also a good source of vitamin E and other antioxidants like flavonoids, belonging to the polyphenol family, and also of the amino acid l-arginine. On the negative side, nuts are quite energy rich so it’s best not to go overboard with nut consumption. But most people eat too few and should increase their nut intake. A handful of nuts is sufficient to enjoy the benefits.

Fighting it out – which is the best nut?

The winner seems to be walnuts with almonds close on its heels. But any other nut might be good too. Let’s look at some details.

A scientific study from 2012 positioned walnuts in the number one slot among a family of foods that lay claim to being among Mother Nature’s most neatly packaged foods. The study measured free and total polyphenols in nine types of raw and roasted nuts. The samples included walnuts, almonds, peanuts, pistachios, hazelnuts, Brazil nuts, cashews, macadamias, and pecans. Walnuts had the highest free and total polyphenol levels in both the raw and roasted samples. Walnuts had a combination of more healthful antioxidants and higher quality antioxidants than any other nut. A handful of walnuts contained almost twice as much antioxidants as an equivalent amount of any other commonly consumed nut. The study suggested that consumers should eat more walnuts as part of a healthy diet.

Another scientific study published in 2014 more directly explored the health benefits of a nut diet by using almonds only. The scientists found that eating almonds reduced the risk of heart disease by keeping blood vessels healthy. They tested the effects of a short-term almond-enriched diet on healthy young and middle-aged men as well as on a group of young men with cardiovascular risk factors including having high blood pressure or being overweight. A control group ate what they normally would, while another group consumed snacks of 50g of almonds a day for one month.

At the end of the study period, the group eating an almond-enriched diet had higher levels of antioxidants (alpha-tocopherol) in their blood stream, improved blood flow and lower blood pressure, potentially reducing their risk of heart disease. The research team speculated that is was the combination of beneficial substances such as vitamin E and healthy fats, fibre which increases the sense of fullness, and flavonoids which may have antioxidant properties, all working together to create the overall health benefits rather than just one particular nutrient in isolation. These findings add weight to the theory that Mediterranean diets with lots of nuts have big health benefits. The scientists suggested that almonds could replace a daytime snack or be added to regular meals like porridge or muesli to help reduce the risk of heart problems.

Seven walnuts a day to get the potential health benefits (Photo: Wikimedia)

Seven walnuts a day to get the potential health benefits (Photo: Wikimedia)

A bit of a dead heat

So as predicted from the start it might not matter which nut you pick. Although not equally good, they might all be good enough to protect your health.

However, there’s another advantage in choosing walnuts as a source of antioxidants. People usually eat walnuts raw, and get the full effectiveness of those antioxidants, while other nuts might be eaten roasted and the heat from roasting nuts generally reduces the quality of the antioxidants.

Remember, it takes only about 7 walnuts a day to get the potential health benefits uncovered in a range of studies. So start adding nuts to your daily diet.

The pervasive obesity curse

Obese (Photo: Malingering)

Excess body weight an increasing problem (Photo: Malingering)

Excess body weight is a major individual, societal and economic problem as it is spreading globally, still increasing rapidly, and can have many and varied health consequences. In its more severe forms, obesity places huge financial burdens on governments and individuals and has been reported to account for up to six per cent of total health care costs in some developed countries.

There is a negative stigma attached to overweight and obesity and a high public awareness of the associated health risks as reflected in a wealth of dietary advice published almost daily. Public health campaigns have long warned against excess body fat and promoted messages highlighting the importance of a healthy diet and moderate exercise. Yet it is a conundrum that much of current prevention strategies for limiting weight gain seems to be simply ignored by individuals and society alike. Individuals continuously make choices in their everyday life to evade a multitude of risks, but excess weight gain seems not to be prioritised. Society continues to provide tempting food choices and facilitates sedentary lifestyles. Intensive promotion of energy-dense food and drink to children and adults has created a new food model of convenience. The structure of the built environment affects obesity by restricting physical activity.

In its simplest form it is clear that excess weight gain is caused by an imbalance between an individual’s energy consumed and energy spent, acknowledging genetic differences in metabolic rate. Obesity could be seen as an unintended consequence of affluence leading to overindulgence, a sedentary lifestyle and bad food choices by the individual. However, it is now commonly agreed that the reasons for the growth in overweight and obesity are multifactorial. Instead of seeing it as a weakness of the individual, it makes much more sense to view obesity as a societal problem involving the interaction of the individual with what has been called the “obesogenic” society.

Fast food contributing to weight gain (Photo: Tony Evans)

Fast food contributing to weight gain (Photo: Tony Evans)

The twenty-first century is a fast moving society where multitasking and food convenience are promoted. Time has become increasingly precious and fast food that can provide satiety in the shortest time possible has become the norm in an increasing number of societies. Globally, the availability of energy-dense and refined foods for easy consumption, foods often high in fat and sugar, have led to excessive energy intake. Sugar and fat are powerful sources of neurobiological rewards. Energy-dense foods provide more sensory enjoyment and more pleasure.

Fast food has become synonymous with time efficiency and has become a middle class status symbol of efficiency in poor countries. But fast food has also, because of its success, become food that is low in price and affordable for people on low income and the poor in rich countries.

It is time for an overall system change. We need to rethink the way we design cities and make them conducive to a healthy lifestyle. Healthcare systems should focus more on prevention and primary care. We need to reconnect with food and teach food skills to young people. We need to take back our urban environment and stop letting it become an advertising space for food and drink companies selling unhealthy choices. Without decisive action, overweight and obesity might become the new normal.

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Anyone for porridge?

Beneficial compounds found in oats (Photo: Cheryl Colan)

Beneficial compounds found in oats (Photo: Cheryl Colan)

I didn’t think so, porridge might not be your favourite food. It is a bit messy to prepare and it is difficult to clean the pots afterwards. But there are other ways to increase the consumption of oats. Think breakfast cereals and why not bread or biscuits, but about all else think carefully of trying to raise your oat intake. Horse trainers already know the benefits of oats. Why should horses be the only beneficiaries?

Seriously though, there is now a new reason to eat oats for heart health and a range of other diseases. It is already known that the soluble fibre in oats helps lower total and low-density lipoprotein (LDL) cholesterol, but scientists now say that the cardiovascular health benefits of oats goes beyond fibre.

The beneficial compounds in oats identified

Eating whole grains has been consistently linked to a reduced risk of several chronic diseases, including cardiovascular disease. Most of the benefits have been attributed to the relatively high fibre, vitamin, mineral and phytochemical content of whole grains. And in particular, the soluble beta-glucan fibre found in oats has been recognised for its ability to lower both total and LDL cholesterol.

Now, scientists have emphasised growing evidence that phenolic compounds called avenanthramides might be behind most of the benefits seen.  There are about 40 or so different avenanthramides found only in oats and three of them in particular seem to act as potent antioxidants, anti-inflammatory, anti-itch and anti-cancer agents, which may provide additional protection against coronary heart disease, colon cancer, and skin irritation.

Avenanthramides are a type of oat phytoalexins that are found in the whole grain with the fibre-rich bran portion of the grain intact. Phytoalexins are substances produced in plants that act as toxins attacking organisms like fungi. They may puncture the cell wall of the fungus, delay maturation, disrupt metabolism or prevent reproduction. Accordingly, researchers have found that oat cultivars with the strongest resistance to crown rust, a fungus that affects oat grains, had the highest concentration of avenanthramides. It is thus possible for  farmers to select highly resistant oat cultivars to increase the production of avenanthramides in the grain.

So many good things linked to oats

Delicious oat bread is even good for you (Photo: Theresa Carle-Sanders)

Delicious oat bread is even good for you (Photo: Theresa Carle-Sanders)

Health-conscious consumers have long chosen foods that include oats because of prominent and snappy “heart healthy” claims made by oats producers. And right they were. Compared to vitamin E, which is a strong well known antioxidant, the antioxidant effect of the avenanthramides is initially weaker but instead the effect is prolonged. But there is more.

Scientific studies have shown that avenanthramides also hinder the ability of blood cells to stick to artery walls, and arrests smooth muscle cell proliferation. Both events known to cause arterial lesions contributing to the development of atherosclerosis, which can eventually lead to heart attack. Earlier human clinical studies have also shown that consumption of oats reduces blood pressure.

But there is even more and I don’t want to sound as a salesman. However, you need to know that colloidal oatmeal can be used for the symptomatic relief of dry skin and itching. Human skin tests have shown that avenanthramides inhibits the release of  histamine that play a major role in itch sensation and reddening of skin. Avenanthramides have already been used as an ingredient in shampoos and topical sprays for the relief of adverse skin conditions, including atopic dermatitis.

So next time you hear that oat is good for you, you better believe it.

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Be kind to your gut microbiota

The gut microbiota important for well being (Photo: Wikimedia)

The gut microbiota is important for our well being (Photo: Wikimedia)

We have written about it before, but to be honest you might not want to know the details of what is inside your gut. I can tell you, though, that it is very important for your well being. In case you got curious, it is called the gut microbiota, a mix of maybe 100 trillion microorganisms, and can weigh up to 2 kilograms that you carry around with you on a daily basis.

Why not deduct it when you next step on the scale? It should be fair enough.

One third of our gut microbiota is common to most people, while two thirds are specific to each one of us. That is to say that the microbiota in your intestine is like an individual identity card. Not that anyone will use it as such, I wouldn’t think.

A most complex ecosystem

The large number of different microbial communities that can be found in the human gut and their impact on human health and disease is a most exciting new area of research. The gut microbiota contains a vast number of microorganisms from all three domains of life, including bacteria, fungi, and viruses. These interact in a complex way to contribute to our well being. It has long been a dark corner of missing knowledge, but the application of advanced DNA sequencing technology has been of an immense help in starting to better identifying the inhabitants.

The microorganisms in the gut can be broadly divided into prokaryotes (bacteria and archaea), bacteriophages (viruses that infect prokaryotes), eukaryotic viruses, and the meiofauna (microscopically small benthic invertebrates that live in both marine and fresh water environments — primarily fungi and protozoa). Of these, bacteria have been the most extensively studied. The gastrointestinal tract is now considered one of the most complex microbial ecosystems on earth and understanding how the multiple communities interact presents both opportunities and challenges.

Competitive pressure

And there is a life and death fight between the different kinds of inhabitants. It has long been known that the bacteria in the gut play an important role in both health and disease. It is also now becoming clear that the non-bacterial microbiota interacts in a complex way with the bacterial microbiota to contribute to these processes. The most common viruses in the gut are the bacteriophages. They infect and destroy bacterial cells and also have the ability to transfer genetic material from one bacterium to another, with potentially profound implications for health and disease.

There is a predator–prey relationship between bacteriophages and bacteria that can change the composition of the bacterial microbiota in conditions such as inflammatory bowel diseases. Bacteriophages induce immune responses in bacteria and transmit genomic material into bacteria that may alter their function. It makes them extremely important and we have only started to scratch the surface of understanding what they do.

There is also a fight between fungi and bacteria. Decreases in fungal diversity have been shown to be associated with an increase in healthy bacterial colonisation following probiotic therapy, suggesting niche competition between fungi and bacteria.

But there are disturbing signs

Antibiotics are valuable, potentially life-saving tools that have significantly reduced human morbidity and mortality. Unfortunately, antibiotics may also have unintended consequences from their off-target effects that may increase the risk of many long-term conditions. Recently,  a possible link has been detected between antibiotic use in childhood and weight gain—with disruption to the normal gut microbiota considered the most likely cause.

It has also been suggested that over-use of antibiotic therapy might be fueling the dramatic increase in conditions such as obesity, type-1 diabetes, inflammatory bowel disease, allergies and asthma, which have more than doubled in prevalence in many populations. There is evidence that microbiota resilience decreases with each subsequent course of antibiotics and that, once disrupted, the normal microbiota may never recover completely or it may be replaced by resistant organisms.

So be kind to your gut microbiota

Low-fat yoghurt good for health claim researchers

Probiotics in fermented food can restore the gut microbiota

Take good care of your gut microbiota. The food you eat can have a profound effect.

Many studies have demonstrated the beneficial effects of prebiotics and probiotics on our gut microbiota. Serving as “food” for beneficial bacteria, prebiotics help improve the functioning of microbiota while allowing the growth and activity of beneficial bacteria.

Present in some fermented products such as yoghurt, probiotics help gut microbiota keep its balance, integrity and diversity. Although authorities are still to be convinced of the cause and effect of individual preparations on the growth of beneficial bacteria to award any of them a health claim status.

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