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.

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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.

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.