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.

yeast-extracts

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.

stress2

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?

Animal_foods

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.

 

Surprising glutamate judgement

Chinese-Food

Chinese food often contain MSG

Yes, I am surprised by the European Food Safety Authority’s (EFSA’s) 2017 verdict on glutamate. As it happens I was involved in an assessment of glutamate in the mid 2000’s. At the highest government level in New South Wales (Australia) illness was claimed after consuming a Chinese meal containing glutamate. This led to a heated debate in the Parliament. Of course, being responsible for food safety in the state, we got ordered to investigate. And so we did read the available literature and reviewed testimonial websites.

Our conclusions didn’t please the politicians much. Although we found plenty of websites with testimonial evidence of even near death experiences after consuming meals with glutamate, no clear evidence of ill effects could be ascertained from the scientific literature. Naturally, the Glutamate Association, an industry funded organisation, on their website attempted to balance negative opinions by claiming that glutamate was the most natural substance you could find.

Glutamic acid is a naturally occurring amino acid

It is true that glutamic acid is a naturally occurring substance in some foods. Glutamic acid is a non-essential amino acid, a building block of proteins, naturally produced in humans and occurring in free form in tomatoes, soy sauce, cheeses (Parmesan in particular) and some other foods. Glutamic acid and its different salts, commonly referred to as glutamates, are also authorised food additives in many countries. They are added to a wide range of foods to enhance their flavour by giving them a “savoury” or “meaty” taste. The most commonly known salt is monosodium glutamate or MSG.

Glutamic acid is the most abundant free amino acid in the brain and functions as an excitatory or stimulating neurotransmitter. It also serves as an important potential energy source. When the glucose concentration in the brain is low, the brain mobilises glutamate. So it is actually quite useful.

Toxicity of glutamic acid/glutamate

Previous evaluations of glutamic acid/glutamates have in the main found little evidence of consistent toxic effects. There is some evidence that experimental ingestion of large amounts (≥3g) of glutamate salts in the absence of food may provoke some symptoms in humans that, although unpleasant, are neither persistent nor serious. However, there is little evidence that those effects occur in the presence of food, the real life situation.

JECFA_meeting

JECFA meeting to discuss food safety

Thus, at its meeting in February 1987, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) stated that glutamate salts were of low toxicity and did not constitute a health hazard as a result of their natural presence in food or use as flavouring agents. Meeting in May 1990, the European Union Standing Committee for Food also judged that the natural occurrence of glutamate in food and its use as a food additive did not present a hazard to health. In its 2003 review, Food Standards Australia New Zealand (FSANZ) concluded that there is no convincing evidence that MSG is a significant factor in causing systemic reactions resulting in severe illness or mortality.

The previous opinions were again supported by JECFA when, in its latest evaluation in 2004, it maintained the previously established ‘not specified’ group Acceptable Daily Intake (ADI) for glutamic acid and its salts. Equally, the Select Committee on GRAS Substances (SCOGS) of the US Food and Drug Administration in 2015 confirmed that glutamic acid and its salts posed no reasonable hazard when used at current levels and practices.

Surprising change of view

In the EU the addition of glutamates is generally permitted up to a maximum level of 10 g/kg of food. In salt substitutes, seasonings and condiments, there is no numerical maximum permitted level for glutamates, but they must be used in line with good manufacturing practices.

This might change after EFSA re-assessed the safety of glutamates used as food additives and derived a group Acceptable Daily Intake (ADI) of 30 mg/kg body weight (bw) for six glutamate salt additives. This safe level of intake was based on the highest dose at which scientists observed no adverse effects in animal toxicity studies.

EFSA also concluded that estimated dietary exposure to glutamic acid and glutamates may exceed not only the safe level, but also doses associated with adverse effects in humans for some population groups. On this basis, EFSA’s experts recommended reviewing the maximum permitted levels for these food additives.

So what’s behind the change of mind

Many animal studies of the effects of glutamate have included too few animals or shown conflicting results. Thus, EFSA in reviewing the scientific literature found no consistently reported adverse effects in available short-term, subchronic, chronic, reproductive, developmental, genotoxicity and carcinogenicity studies.

So far so good.

swiming_rat

Delayed swimming development

However, dietary neurodevelopmental toxicity was identified in several mouse and rat studies, some of limited quality. One study was adequate showing delayed early swimming development, diminished rearing frequency in the open field, altered active avoidance acquisition and prolonged passive avoidance retention caused by MSG.

Not so good.

Peculiar as the effects might sound, this study was used to set a dose of 3,200 mg MSG/kg bw per day as safe based on the absence of neurobehaviour effects which occurred at higher doses (a NOAEL – or no-observed-adverse-effect-level).

Toxicologist normally use an uncertainty factor of 100 when translating results from animal studies to humans giving the 30 mg/kg bw per day calculated as glutamic acid as an acceptable intake after rounding.

The study on which EFSA based its recommendations is not new as it was published in 1979 and available to all previous reviews cited above. It can only be assumed that EFSA considered also human findings where glutamate has been associated with the MSG symptom complex (> 42.9 mg/kg bw per day), headache (85.8 mg/kg bw per day), blood pressure increase (150 mg/kg bw per day) and also insulin increase (> 143 mg/kg bw per day).

None of these findings were robust enough on which to base calculation of an ADI. But the selected animal study allowed calculation of an ADI that would be protective for any of the reported human findings.

Are we safe now?

Good question and unfortunately the answer is no looking at the provided exposure assessments.

When EFSA’s scientists (including my good friend Davide Arcella) combined food consumption data with glutamate additive levels in food they found that exposure may exceed the proposed ADI for individuals of all population groups whose diet is high in foods containing these additives, as well as for toddlers and children with medium exposure. Exposure may also exceed doses associated with some adverse effects in humans (e.g. headache) for highly exposed infants, children and adolescents.

EFSA’s experts also considered other dietary sources of glutamate besides food additives (including natural presence and addition as nutrient). They found that exposure estimates largely exceed, in several population groups with medium to high exposure, both the proposed ADI and levels associated with some adverse effects in humans.

What do we do?

headache

Headache part of the MSG symptom complex

For years, consumer concerns about adverse effects of glutamate have been dismissed, but now when EFSA has confirmed possible health effects what should we do to limit the potential impact?

If taken seriously, the proposed ADI might trigger a rush by food manufacturers to remove glutamate additives where possible, but don’t hold your breath.

If agreed by other Government authorities, we might see new maximum use levels proposed and also a reduction of the number of food categories in which these additives are permitted. This might happen first in Europe, but countries outside Europe might await a recommendation from JECFA.

Finally, as a consumer you might find some reassurance in the fact that only 1-2 per cent of the population is considered to be extra susceptible to the adverse effects of high levels of glutamates.

We will see how the world reacts. EFSA has sometimes been criticised for being too lenient (see BPA and glyphosate). This time they have gone the opposite way.

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.

Additive ruling on nitrate and nitrites

sausages2IARC (International Agency for Research on Cancer) is sometimes very quick to nominate any chemical as at least a probable carcinogen. And so it is with nitrate and nitrite. Pointing to the endogenous nitrogen cycle in humans (that is ingested nitrate recirculated in saliva and converted to nitrite by microorganisms in the mouth and swallowed) IARC concluded that both nitrate and nitrite are probable human carcinogens as they can generate carcinogenic N-nitroso compounds under acidic gastric conditions.

Now let’s make it clear, EFSA in two recently published opinions on nitrate and nitrite partially supported the IARC conclusions on the link between nitrates and nitrites in processed meat and an increased risk of colorectal cancer. But, and this is a big BUT….

Both additives are considered safe to use at current approved levels without any concerns. So why is that?

Nitrate and nitrite cleared as additive at current levels

EFSA, in contrast to IARC, not only looks at the potential for a substance to cause cancer, but also the exposure level necessary. That is practical life conditions. And concluded that existing safe levels for nitrates and nitrites intentionally added to meat and other foods are sufficiently protective for consumers.

Case closed? Well, not so fast. Let’s look at some of the detail.

EFSA’s Panel on Food Additives and Nutrient Sources Added to Food said that there is some evidence in epidemiological studies of a link between dietary nitrite, preformed N-nitroso compounds and gastric cancers and also for the combination of nitrate plus nitrite from processed meat and colorectal cancers. However, they stressed that this included only very limited evidence.

Using refined exposure assessment scenarios, the Panel calculated that exposure to nitrites as a food additive accounts for 17% of total exposure to nitrite and exposure to nitrates as a food additive only accounts for up to 5% of total exposure to nitrates. Other sources making up the balance of exposure include their natural presence in other food products and environmental contamination.

The main contributors to exposure are vegetables and vegetable-based foods, such as starchy roots, leafy vegetables, such as spinach and lettuce, and prepared salads. Nitrates also contaminate water as a result of intensive farming, fertilisers and sewage discharge.

The remaining problem

rucola

Although the use of nitrate and nitrite as additives have little influence on overall exposure, there is still a remaining overall concern.

If all sources of dietary nitrate are considered, such as food additive use, natural presence in food and environmental contaminants, the Acceptable Daily Intake may be exceeded for individuals of all age groups with medium to high exposure.

If all sources of dietary nitrite are considered, the Acceptable Daily Intake may be exceeded for infants, toddlers and children with average exposure, and for highly exposed individuals of all age groups.

However, the estimated formation in the body of N-nitroso compounds from nitrites added to food items at the approved level were far below those that could be considered to be of risk to human health.

To further reduce uncertainties, the Panel made several recommendations, including:

  • additional studies to measure the excretion of nitrate into human saliva, its conversion to nitrites, and the resulting methaemoglobin formation (a potential problem in babies);
  • further studies on the levels of N-nitroso compounds formed in different meat products based on known amounts of added nitrites/nitrates;
  • large-scale epidemiological studies on nitrite, nitrate and nitrosamine intake and risk of certain cancer types.

In the meantime an Acceptable Daily Intake of 0.07 mg/kg body weight for nitrite and 3.7 mg/kg body weight for nitrate as food additives would be of no concern as most people would not exceed it through eating food to which the additives had been added and only some children would slightly exceed nitrite additive exposure.

Surprising details about salt

water2We recently published a blog abut the health impact of high salt intake. We told you that the body relies on sodium from salt for a variety of functions, including blood pressure and the transmission of nerve impulses. And that it is important that the sodium level in blood is carefully maintained.

But there is more.

The conventional wisdom has long been that if you eat a lot of salt you will become thirsty and drink water, diluting your blood enough to maintain the proper concentration of sodium. Ultimately, you will get rid of the excess salt and water through urine. One way of increasing urine production is to increase blood pressure – the negative health impact of too much salt in the diet.

Sounds simple enough, but some of this may be very wrong.

Surprising findings

Two new studies have put part of this simple theory on its head. In long-term studies of simulated space travel the participants were given a well controlled diet with either 6, 9 or 12 g of salt per day. Eating more salt actually made the participants less thirsty, but somehow hungrier despite the amount of food being exactly the same.

Instead of drinking more, the participants were drinking less when getting more salt. But still increased urine production to get rid of the excess sodium. So where was the excreted fluid coming from? Well, the only explanation available would be that the fluid had been generated from existing body constituents.

How bizarre!

To get to the bottom of the findings the scientists repeated the experiments on mice and found that they burned more calories when they got more salt in the diet. Since they had unlimited access to food – in contrast to the humans above – they ate 25% more just to maintain their weight.

The animals were getting water – but not by drinking it. Instead an increased level of glucocorticoid hormones helped break down fat and muscle in their own bodies. This freed up water for the body to use. However, this process requires energy, thus the mice ate more food.

We already know that a starving body can burn its own fat and muscle for survival. That something similar happens on a salty diet was a surprise. But this is what camels do to create water from the fat in their humps when travelling through deserts with no water.

No, it’s no dieting solution

dieting_(fantasyhealthball)

So could this be a new weight loss fad? To eat more salty foods as salt seems to be involved in weight loss. In contrast to the previous opinion that a high-salt diet encourages a greater intake of fluids, which increases weight.

No, the advice is not to increase salt intake for three reasons:

  • Firstly, more salt in the diet will make you hungrier and you will eat more unless you have a very strong resolve. This would defeat the purpose of the dieting.
  • Secondly, the resulting high glucocorticoid levels are known to cause osteoporosis, muscle loss, diabetes and other metabolic problems.
  • And finally, the increased blood pressure due to the high salt intake can cause heart disease and premature death.

So it is a no brainer to still reduce salt intake. But at least now you know more about what happens when you eat too much salt.

Disappointing news – or not – about moderate drinking

heart

Many studies and reviews have supported the notion that moderate alcohol consumption is beneficial for heart health. Why not have a daily glass or two of wine at dinner, as it could ward off disease. And now they come and spoil the fun.

A joint group of Canadian, Australian and US scientists took a hard look at the evidence presented in previously published research and found little support for a heart protective effect of moderate alcohol consumption.

And here you are believing the previously good news, who can you really trust? But not all is lost so read on.

So what did they find?

The new assessment initially agreed with the previous findings as a fully adjusted pooled analysis of all the 45 studies reviewed found significantly reduced coronary heart disease mortality for current moderate drinkers, actually for all current drinkers.  So all good now, can I continue to have a glass or two of wine to dinner and feel healthier?

Unfortunately not, as the researchers found confounding factors in that they could see an influence of age, gender, ethnicity, and heart health at baseline. When correcting for such factors they claim that moderate consumption of alcohol was not significantly protective for people at ages 55 years or younger at baseline, or for studies controlled for heart health at the beginning of the study. They even claimed that the appearance of cardio-protection among older people may reflect systematic selection biases that accumulate over the life course.

Their hypothesis is that non-drinkers may, in fact, be former drinkers who quit or cut down for health reasons. So, of course the remaining healthy drinkers will fair better than their poor abstainers that are already sick. And the seniors who are healthy may be more likely to keep enjoying that glass of wine with dinner thus biasing the results.

However, the researchers stop short of turning the previous findings on its head. They only conclude that there remain grounds for skepticism about the hypothesis that alcohol use can be cardio-protective, and recommend that future prospective studies not only avoid biased abstainer reference groups, but also take steps to minimize other forms of selection bias across the life course, including that from competing disease risks.

So there is still hope?

red_wine_(boo_licious)Yes, there is still hope that a daily glass of wine might keep you healthy longer as the researchers can’t prove it one way or the other. Only that there are grounds for a healthy skepticism as there remain plausible alternative explanations for their observed review findings.

So let’s make it clear. For now, no one is saying that people who enjoy alcohol in moderation should stop. Should there be no direct benefits, at least the risks of low-level drinking would be small.

Let’s drink to that, but only in moderation!

Salt satisfaction

salt2Sodium serves a vital purpose in the human body as it helps nerves and muscles to function correctly, and it is an important compound involved in maintaining fluid balance. Most of our dietary sodium intake is provided through the consumption of sodium chloride (common or table salt). About 80 per cent of this would come from processed foods and 20 per cent from salt used at the table or in home cooking. Table salt is made up of just under 40 per cent sodium by weight, so a 6 g serving (1 teaspoon) contains about 2,400 mg of sodium (note that some of the calculations below use the more exact 39 per cent of sodium).

Apart from table salt, it has been estimated that a further ten per cent of dietary sodium intake would be provided from naturally occurring sodium or sodium-containing food additives.

So far so good, but unfortunately high intakes of sodium can increase blood pressure, and high blood pressure can increase the risk of developing heart and kidney problems. To limit the negative effects of consuming too much sodium the World Health Organization (WHO) recommends that daily sodium intake should not exceed 2,000 mg (equivalent to 5 g of salt).

Initial reassuring results for the Australian population

Estimates of salt intake is most often made using a 24 h diet recall methodology. Using this method, Food Standards Australia New Zealand (FSANZ) in 2008 estimated that daily intake of salt across all Australians was 5.5 g. This amount of salt would deliver an average of around 2,150 mg sodium per day. Taking into account non-salt sources of sodium and salt added by the consumer, FSANZ assumed a probable daily sodium intake of around 2,500 mg. Even if small reductions in sodium intake can lead to big health benefits, this was considered to be close enough to the WHO recommendations. However, because this is an average, there would be a lot of Australians who eat more than this and more than the recommended maximum intakes.

A repeat diet recall survey to update the estimate of mean daily salt intake was performed in 2011-12 through the Australian Health Survey (AHS) with slightly higher results at 6.2 g for the Australian population, equivalent to 2,404 mg of sodium. In this case the amount included sodium naturally present in foods as well as sodium added during processing, but excluded the discretionary salt added by consumers in home prepared foods or at the table. Adjusting for the latter might indicate a daily sodium intake of 2,600 mg per person, which is still only marginally higher than the WHO’s recommended maximum of 2,000 mg and therefore little cause for alarm.

But now for the bad news.

eat-less-saltNow new research shows that the dietary recall method used by the AHS and others likely substantially underestimate mean population salt consumption. The researchers suggested that Australians are consuming 50 per cent more salt than what was previously thought.

Researchers at George Institute for Global Health analysed the salt intake of 419 residents of Lithgow in NSW using two methodologies – the previous 24 h diet recall questionnaire but also 24 h urine samples. Based on the diet recall method, which was used by AHS, the average Lithgow resident consumed 6.8 g a day when including discretionary use. But based on 24 h urine collections, the researchers were able to conclude that the average was actually 9.0 g per day, equivalent to 3,545 mg of sodium. Correcting for salt lost through non-urinary excretion, the average was adjusted to 9.9 g per day or 3,900 mg of sodium.  This is almost double the WHO’s target for daily salt and sodium intake and suggests a several folds greater disease burden attributable to excess salt consumption in Australia.

The lesson

This is but one example of the challenges involved in estimating food intake. The 24 h recall method is considered superior to the food frequency questionnaire method so often used in epidemiological surveys. Still it showed a considerable bias. Again I suggest that epidemiological correlations between food intake and disease should be taken with a grain of salt (pun intended).

New liquorice warnings

liquorice_candy_(US_Government)

Liquorice is a popular sweetener found in many soft drinks, food products, snacks and herbal medicines. It has a rich history as an old remedy that was used by ancient Egyptians and Assyrians made into a sweet liquid drink. There is a traditional belief that liquorice is a healthy natural substance without side effects driving its liberal consumption that can occasionally be hazardous.

If you have followed this blog for a while you might remember that we have covered the good and the bad of liquorice before. Now we also cover the ugly.

The good

Liquorice is extracted from the roots of the plant Glycyrrhiza glabra, a member of the pea family. Most liquorice roots are wild-harvested with collection occurring mainly in Central Asia (Iran, Turkmenistan, Afghanistan and China). Liquorice extract is produced by boiling liquorice root and subsequently evaporating most of the water. Large-scale extraction is limited to China and Iran. Glycyrrhizin, that is 50 times sweeter than sugar, is the main active component in liquorice extract and apart from sweetness also provides the desirable liquorice flavour. Moderate consumption of liquorice is associated with several health benefits in that it can quickly soothe sore throats and coughs among some other positive effects.

The bad

Unfortunately, it has long been known that excessive and prolonged consumption of glycyrrhizin intensifies the effects of the stress hormone cortisol by inhibiting the enzyme that inactivates cortisol and may interfere with the sodium and potassium balance. High levels may increase hypertension. Thus, it has been suggested to limit consumption of glycyrrhizin to 100 mg per day, the approximate amount found in 60–70 g of liquorice candy. However, it is not that easy to estimate intake of glycyrrhizin as various forms of candies, beverages, supplements and extracts contain very different amounts of the active components.

The ugly

Pregnant womenRecently new warnings were issued by the Finnish National Institute for Health and Welfare to women to avoid consuming large amounts of liquorice during pregnancy as it can have long-term harmful effects on the development of the foetus. A new Finnish study had shown that youths previously exposed to large amounts of liquorice in the womb performed less well than others in cognitive reasoning tests carried out by a psychologist. The difference was equivalent to approximately seven IQ points.

Those exposed to liquorice also performed less well in tasks measuring memory capacity, and according to parental estimates, they had more ADHD-type problems than others. With girls, puberty had started earlier and advanced further.

In this study a large amount was defined as daily consumption of more than 70 mg and compared to consumption of less than 35 mg glycyrrhizin.

The lesson

Although cortisol is essential to the development of a foetus, large increases initiated by excessive consumption of liquorice can be detrimental.

Ignoring responsibility at your peril

oil_(Illuminati Owl)

Oils aren’t always what they say (Photo: Illuminati Owl)

The agri-food industry is no innocent bystander. Maximising sales and profit is more important than looking after their customers. They cleverly invent crops tolerant to their own herbicides through genetic engineering so they can sell both seeds and encourage the spread of questionable poisons. They add sugar to many of their products for children so that people will crave sweet foods throughout life. They cheat on extra virgin oil because they can and reap the profit. They replace beef in processed beef products with cheaper horse meat to gain an upper hand. The lists goes on and on.

And rightly the public is upset. This is reflected by the many news items published by the popular press condemning the latest cheat by industry.

But what about consumer responsibility?

Acrylamide is a good example as it is formed during heating of food as we have previously pointed out. Evidence from animal studies have shown that acrylamide and its metabolite glycidamide are genotoxic and carcinogenic: they damage DNA and cause cancer. While evidence from human studies on the impact of acrylamide in the diet is inconclusive, scientists agree that acrylamide in food has the potential to cause cancer in humans as well and it would be prudent to reduce exposure.

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Go easy with the toaster (Photo: DonoVan Govan)

Thus, in early 2017, the UK Food Standards Agency issued consumer recommendations on how to minimise the formation of acrylamide during home cooking by avoiding singeing their toast or leaving roast potatoes to char in the oven.

Acrylamide is a natural by-product of heating and has been present in our food since fire started to be used for food preparation. It is formed by a reaction between amino acids and sugars when foods are heated at high temperatures (over 120°C) during frying, roasting or baking. It can thus be found in a wide range of foods including roasted potatoes and root vegetables, chips, crisps, toast, cakes, biscuits, cereals and coffee.

The formation of acrylamide can be reduced by some simple measures as pointed out by the Food Standards Agency. Aim for a golden yellow colour or lighter when frying, baking, toasting or roasting starchy foods like potatoes, root vegetables and bread. Carefully follow cooking instructions on the pack when frying or oven-cooking packaged food products such as chips, roast potatoes and parsnips. Don’t store raw potatoes in the fridge as it may lead to the formation of more free sugars in the potatoes that can increase overall acrylamide levels.

Parts of the popular press objected

All sensible and practical recommendations. You would have thought that the popular press would support such a consumer initiative. But you would be wrong. Rather, parts of the press attacked the Food Standards Agency for being alarmist. Critics of the advice were quick to point out that animal studies linking acrylamide to cancer have used doses far above the average daily consumption in humans so that extrapolating the results is questionable – even assuming the effect is comparable across species.

DNA

Acrylamide is a genotoxic carcinogen.

But genotoxic carcinogens don’t follow the minimum threshold concentration rule below which they are not dangerous at all. With chemicals that damage DNA it’s a linear dose response, so even the smallest dose contributes to the risk. There is no threshold dose for the effect. And to add to the problem it is almost impossible to prove in epidemiological studies that acrylamide is a human carcinogen as its presence is too common to find a group that is not exposed at all.

Therefore, the united verdict of organisations like the International Agency for Research on Cancer, the World Health Organisation, the European Food Safety Authority (EFSA) and UK scientific advisory committees is that acrylamide has the potential to cause human cancer by interacting with the genetic material in cells. In 2015, EFSA published their risk assessment of acrylamide in food confirming that acrylamide levels found in food potentially increases the risk of cancer for all age groups. This means that acrylamide might contribute to our lifetime risk of developing cancer; although it is not possible to estimate how big this contribution may be.

Time for action

With that united front I suggest that you better follow the recommendations issued by the UK Food Standards Agency. I know that you feel safer when driving your own car compared to flying, although the probability of an accident is much higher on the road. I know that it is so much easier to blame the food industry for all ills, rather than take some responsibility for your own food handling.

Maybe it’s time for some action!