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

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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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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

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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.