BMJ: What is junk food and what is the harm?

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Adapted from: BMJ 3 Sept 22 People need nourishing food that promotes health, not the opposite by Carlos Monteiro et al.

Everybody needs food, but nobody needs ultra- processed food with the exception of infants who are not being breast fed and need infant formula.

The foods that are “ultra- processed” include: soft drinks, packaged snacks, commercial breads, cakes and biscuits, confectionery, sweetened breakfast cereals, sugared milk based and fruit drinks, margarine and pre-processed ready to eat or heat products such as burgers, pastas and pizzas.

These foods are industrial formulations made by deconstructing whole foods into chemical constituents, altering them and recombining them with additives into products that are alternatives to fresh and minimally processed foods and freshly prepared meals.

In low amounts, they wouldn’t necessarily be a problem. But most ultra- processed foods are made, sold and promoted by corporations, typically transnational, that formulate them to be convenient, ready to eat, affordable, due to low -cost ingredients, and hyperpalatable. These foods are liable to displace other foods and also to be overconsumed.

Systemic reviews of large well -designed cohort studies worldwide have shown that consumption of ultra-processed foods increase: obesity, type two diabetes, hypertension, cardiovascular and cerebrovascular diseases, depression, and all- cause mortality.

Other prospectively associated conditions include dyslipidaemias, gout, renal function decline, non-alcoholic liver disease, Crohn’s disease, breast cancer and in men colorectal cancer. They also cause multiple nutrient imbalances.

It is calculated that ingestion of these foods compared to fresh ingredients, matched for macronutients, sugar, sodium and fibre adds a typical 500kcal daily, which leads to the inevitable fat accumulation.

US investigators have found that dietary emulsifiers and some artificial sweeteners alter the gut bacteria causing greater inflammatory potential, so replacing sugar with these isn’t a good idea either.

In the UK policies to limit promotion and consumption of ultra-processed food have recently been rejected, mainly because of the belief that in our current economic situation people need access to cheap food. As no one really wants to support foods that cause illness, the obvious solution is to promote foods that are fresh and minimally processed, available, attractive and affordable. Such a strategy would improve family life, public health, the economy and environment.

There are physiological reasons why your brain feels full up after a day’s work

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Adapted from Medscape, Why our brains wear out at the end of the day, F Perry Wilson Aug 15 2022

We can all recognise from our own experience that as a long day goes on, our performance on mental tasks gets worse. In chess players for example, as the game goes on over several hours, they take longer to make decisions, and they make more mistakes. This is known as cognitive fatigue.

It has been found that the cognitive control centre in the brain is in the left, lateral, prefrontal cortex.(LLFC).

The LLFC is responsible for higher level thinking. It is what causes you to be inhibited. It shuts down with alcohol and leads to impulsive behaviours. It has reduced activity in functional MRI studies as you become more and more cognitively fatigued. The LLFC helps you think through choices. So how does cognitive fatigue happen? As a matter of interest the role of glucose has already been studied and it has been found that this does NOT vary in non- diabetic subjects.

Researchers did experiments with people to induce cognitive fatigue. They had to look at letters and indicate whether the letter was if it was a consonant or a vowel if it was red or if it was upper or lower case if it was green.

Both groups did this for six hours, but one group had much less switching around than the other, so that there was an “easy” group and a “hard” group. They all sounded terribly tedious to me!

The hard group made more mistakes than the easy group, but of course the task was harder to start with. The hard group got a little bit more tired at the end, but both groups were pretty fatigued. The hard group took longer to respond all through the testing hours, but they didn’t take longer by the end of the task. So, overall, there was no clear indicator that could determine who had done the easy tasks or the hard tasks.

The researchers then started adding a new game after the six hours. The subjects were told that they would now play a “reward game”. For instance:

Would you rather have a 25% chance of earning $50 or a 95% chance of earning $17.30?

Would you rather earn $50 but your next task session will be hard or earn $40 and your next task session will be easy?

It has been previously shown that as people become more fatigued they will tend to pick the low- cost choice over the high- win choice. Perhaps we all recognise that after a difficult workday we may be more likely to go with the flow and do something easy rather than the “best” thing. We often don’t feel we have much decision- making power left. I know this is a factor for prescribing more antibiotics on a Friday afternoon.

Interestingly pupil dilatation is a physiologic measure that demonstrates when your brain is “full up”.

When you are interested in something your pupils dilate a little. In the hard group, as time went on, pupil dilatation stopped and constricted in some people. In the easy group however, the dilatation continued through the tasks.

By doing a very fancy labelled hydrogen MRI on the subjects they looked at differences in brain metabolites in the LLPC area of the brain during the tasks.

They found that the level of glutamate and glutamic acid rose in the LLPC but not other metabolites and not in other parts of the brain. They also found that the glutamate leaked from inside the cells to outside the cells.

It is statistically significant that the higher the levels of glutamate in the LLPC, the more likely you are to just make the easy decision as opposed to really think things through.

Perhaps a good night’s sleep is clearing out the excess glutamate in the LLPC and allowing you to perform well the next day.

My comment: The hours pilots and air traffic controllers work are highly regulated because of the effect of fatigue on decisions and performance. Yet, this does not extend to GPs and hospital doctors to anything like the same extent. It is considered important for lorry drivers. For all drivers and for all students, particularly before exams, it is a good idea to recognise that we are all human. Tiredness isn’t something that you can really overcome with will power.

Colorectal cancer is affected by your experience in the womb

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Adapted from BMJ: 18 Sept 2021

A longitudinal study of women from Oakland California has been following 19 thousand of their offspring since the early 1960s.

So far 68 people have been diagnosed with colorectal cancer.

Risk factors include: obesity in the mother, weight gain during pregnancy, and a high birthweight. This suggests that uterine life has something to do with why this cancer develops. This could explain why there has been a relatively recent increase in colorectal cancer in younger aged adults. Unfortunately there is little you can do yourself about these factors.

Sleep deprivation gives you a fatter belly

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In young adults sleep deprivation has been found to cause fat accumulation in the belly for the first time.

Naima Covassin from the Mayo Clinic Rochester Minnesota studied 12 healthy slim young people aged between 19 and 39. The poor souls were randomised to two weeks of just 4 hours sleep a night or 9 hours sleep followed by a three day recovery period. During this time the subjects were kept in hospital and factors such as calorie intake and energy output were measured.

Over the two weeks of sleep deprivation, the subjects put on an average of a pound or half a kilogram and all of it on the belly.

This was because they consumed an extra 308 calories a day compared to the 9 hours a night group.

Despite stopping the study after two weeks and then during recovery sleeping more, eating fewer calories and their total weight coming down, their bellies continued to get bigger, by an average of 3 cm by day 21 of the study.

This could be why shift workers are so prone to gaining fat around the belly.

The continued rise in belly fat could have been missed if body weight, BMI and overall body fat percentage were the only factors measured.

Dr Harold Bays who is an endocrinologist and president of the Louisville Metabolic and Atherosclerosis Research Centre says “Sleep disruption results in fat dysfunction and this may result in increased cardiovascular risk factors and unhealthy body composition including an increase in visceral fat.”

What do white rings round your corneas indicate?

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Adapted from BMJ 23 Nov 2021

In a German study of ten thousand people aged between 40 and 80 years old, 21% of men and 17% of women had white rings round their irises of the eyes. You may have noticed these in your parents or yourself and may have wondered what this means.

The average age of the group was 60. Researchers noted that corneal arcus is more likely in men than women, increases with age, and increases with lipid levels.

Corneal arcus has no relevance to socioeconomic status, body mass index, arterial blood pressure or HbA1c levels.

A ketogenic drink has been found to improve cognitive performance in those with mild cognitive impairment

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Adapted from A ketogenic drink improves cognition in mild cognitive impairment: Results of a 6 month RCT by Melanie Fortier et al. Alzheimer’s and Dementia. 2021.

Brain energy rescue is being tested to see if it can reduce cognitive decline in patients with mild cognitive impairment. It has previously been discovered that the brain has problems using glucose for fuel even before symptoms develop, but brain ketone use remains constant in both Alzheimers (A) and Mild Cognitive Impairment (MCI). Increasing ketones available to the brain has been shown to improve cognitive symptoms.

A really easy way to increase blood ketone levels is to give a drink containing ketogenic medium chain fatty acids. This has been found to increase brain energy uptake via PET scans. This follow on trial was done to assess whether improvement in cognition after six months occurred.

This study was conducted in Quebec Canada. Very strict entry criteria were applied and the patients were randomised to the ketogenic drink or to a placebo drink. The drinks appeared and tasted identical.

122 participants were enrolled. In total 39 completed the ketogenic arm and 44 the placebo arm. They were well matched regarding age, sex, education, functional ability and cognitive scores, absence of depressive features, blood pressure, blood chemistry and APOE 4 status. ( A genetic variability that greatly increases the chance of developing dementia).

More participants dropped out of the ketogenic group mainly due to gastrointestinal side effects. The drop out rate overall was 32% and 38% in the ketogenic group. None of the side effects were serious.

The results showed that performance on widely used tests of episodic memory, executive function and language improved over 6 months in the ketogenic group compared to the placebo group. Improvement was directly correlated with the plasma level of ketones.

The dose used was 15g of kMCT twice a day.

This seems to be a very reasonable intervention for early cognitive decline particularly since no drugs are approved for MCI and drugs used for Alzheimers do not delay cognitive decline in MCI. It is possible that effects would be enhanced if patients also undertook a ketogenic diet. Further trials are now warranted to see if diagnosis of Alzheimers can be delayed in those suffering from mild cognitive impairment.

Writing down your thoughts can boost your mood

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Adapted from Human Givens No 1 2013 Brinol P et al. Treating thoughts as material objects can increase or decrease their impact on evaluation. Psychological Science 24.1, 41-7. 2013.

Writing down negative thoughts, crumpling them up, and throwing them away, as often advocated by therapists, really does reduce negative thinking. Conversely, writing positive thoughts down, and keeping them safe in a purse or pocket helps you feel better.

Teenage School students in Spain were asked to write down either positive or negative thoughts about their bodies and then Mediterranean diet and they were then evaluated on how much they became influenced by their lists later on.

What they found was that people who threw the list in the trash right away were not influenced, those who kept the list in their desk were somewhat influenced, but that those who kept the list more personally in a pocket or purse were most influenced.

To see if the effect worked with word lists via a computer, the experiment was repeated. The thoughts were put into storage or the trash list. Repeating the experiment but simply asking the students to imagine putting the list in a particular location without physically doing anything was also done.

Professor Richard Petty, a co-author of the paper from Ohio University said, ” The more convinced the person is that negative thoughts are really gone, the better. Just imagining that you throw them away doesn’t seem to work”.

So, to get over a difficult event, write it down, and then bin it and be physical.

If you want to boost your mood, write positive facts or feelings and keep it close and personal.

6.5 to 7 hours sleep a night is about average for adults

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Adapted from BMJ 13 Nov 2021 from American Journal of Epidemiology.

Measurements using an Actigraph were taken from 13,000 adults and children in the USA to determine what a “normal” sleep duration was. The amount of sleep taken by individuals can be highly variable, and this can also change due to their age and stage of life and occupation.

For females, the 50th centile, the middle of the sleep range, was 8.3 hours a night, starting from age 6. As a young adult, this reduced to just over 7 hours and stayed constant till there was a small increase at age 65.

For males, the middle of the sleep range was 8.1 hours at age 6 and reduced to 6.5 hours in early adulthood and increased slightly at age 60.

My comment: I’ve always needed a lot more sleep than this. 10 or 11 is better for me and in autumn, just after the clocks change, I can sleep for 14 hours a night if I am not disturbed. I perk up a little bit in the spring and can cope with 9 hours a night. For much of my life, particularly working as a doctor on call and having young children I had a lot less sleep than I really needed. I have seen that sleeping a lot is associated with a higher rate of dementia, but too bad!

In California, a longitudinal study of more than 50,000 women, looked at how environmental influences affected how long it took to get to sleep and how long the sleep lasted.

Shorter sleep duration was associated with exposure to artificial light at night and air pollution. (Associated with cities). Where there was a lot of environmental noise, it took longer to fall asleep.

Contrasting with this, living in areas with more green space led to women falling asleep faster and staying asleep longer.

Consistent exercise improves your survival if you have a heart attack

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Adapted from BMJ 27 Feb 2021

After a heart attack, the risk of sudden death is influenced by your past levels of physical activity.

People who performed moderate levels of leisure time exercise reduced their risk by 33% and those who performed high levels of exercise reduced the risk by 45%.

This study combined data from ten European longitudinal studies and found 30,000 people who had a heart attack. Around 5,000 people (18%) died within 28 days. Of these, 3,000 (62%) died instantly.

European Journal of Preventative Cardiology

Fish oil supplements however had no worthwhile cardioprotective effects according to a Cochrane Systemic Review done several years ago. A study looking at secondary prevention in 70-80 year olds, recently found similar effects. There was no difference between the omega 3 fish oil supplemented group and placebo over two years.

Cochrane Database Systemic Review and Circulation

Babyhood antibiotics increase the risk of type one diabetes in childhood

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Adapted from Diabetes in Control Antibiotic Treatment increases risk for type one diabetes by Chardae Whitner May 15 2021

Both prenatal and first year of life antibiotic exposure may increase the risk for developing type one diabetes in childhood.

It is believed that early life risk factors which include antibiotic treatment can influence the risk of type one diabetes by affecting the gut microbiome. This affects the development of the immune system. Type one diabetes children have been found to have lower microbial diversity in their gut compared to children without diabetes. Antibiotic exposure in early life delays microbiota maturation.

Sweden has the highest rates of type one diabetes in the world despite a relatively low antibiotic prescription rate. They studied siblings, some affected by diabetes and some not. They looked at antibiotic prescriptions, mode of delivery, sex, birth year and genetic predisposition to type one diabetes. The children studied were born between 2005 and 2013. 797,318 children were studied.

Overall 800 prescriptions for antibiotics were issued in the first year of life. These were most commonly for ear infections, then respiratory tract infections, urinary tract infections, and then skin and soft tissue infections.

Exposure to antibiotics prenatally was associated with an increase in type one diabetes in childhood of 1.15 (so weakly associated). Antibiotic exposure in the first year of life raised this a little to 1.19. (still weak. You would need to have 1,475 babies have antibiotics to have one extra case of childhood diabetes before the age of ten).

Siblings of type ones have a risk of 1.36, so this is a stronger risk than antibiotic exposure.

Caesarian section did give an increased rate of type one diabetes in childhood but sex, genetic predisposition and birth year did not. The risk was 1.10 in vaginally delivered babies and 1.60 in the little caesars. So this was again a bit stronger than sibling risk.

Wernroth, Mona-Lisa et al. Early childhood antibiotic treatment for otitis media and other respiratory tract infections is associated with risk of type one diabetes. Diabetes Care May 2020.

My comment: My son Steven has type one diabetes and had a strong family history on his dad’s side of autoimmune disorders including type one diabetes in several generations. He also was a caesarian section delivery and also had a peri-orbital skin infection when he was about seven months old that required antibiotics. Poor wee soul! These days no one gets a caesarian section without a good reason and antibiotics are well thought out. There isn’t much you can do about being a sibling of someone with diabetes. What you can do is take vitamin D in pregnancy and give it to your children from birth onwards.