Explainer: what is raw milk and why is it harmful?

There is no evidence that the health benefits of milk are compromised by pasteurisation.jacqueline/Flickr, CC BY-NC

 

Authors:
Edward Fox, Food Safety and Microbiology Research Scientist at CSIRO
Narelle Fegan, Food Microbiologist at CSIRO


Milk is a highly nutritious food, and an important source of amino acids and minerals such as phosphorus and calcium, which contributes to bone health.

Historically, milk was prone to contamination by bacteria from cows that could cause severe illness in humans. This remains the case with raw (unpasteurised) milk. The tragic death of a Victorian toddler this week is a stark reminder of these risks.

Pasteurisation involves heating the product to 72°C for 15 seconds. The method was originally employed to destroy bacteria in wine and beer that caused these products to spoil. It was quickly realised that this process could also be applied to milk to destroy harmful bacteria, and make milk safer for human consumption.

Pasteurisation was first introduced in Australia in the late 1950s and remains a legal requirement for milk produced for human consumption in Australia.

Nowadays, some of the important bacteria that pasteurisation targeted, such as those that cause tuberculosis, are no longer as problematic. So why do we continue to pasteurise milk?

The animals we use for milking can sometimes carry other pathogenic organisms that are capable of causing disease in humans. They can be found on hides or shed in the faeces.

Even healthy animals may be a source of organisms that are harmful to people. Such pathogens may be present in the farm environment, including soil, water, on pasture and in animal feeds. These pathogens can enter the milk during milking and if such milk is consumed, it can cause disease.
The most common pathogens found in association with dairy farms and milking animals include bacteria such as Escherichia coli (E. coli), Campylobacter and Salmonella, but other pathogens such as parasites like Cryptosporidium, a type of gastro, may also be present.

As soon as milk is secreted from the udder, it is at risk of contamination
by many different bacteria.  cheeseslave/Flickr, CC BY

Campylobacter and Salmonella can cause severe diarrhoea and certain types of E. coli, particularly those known as Shiga toxin-producing E. coli (STEC), can cause very severe disease which impairs kidney function and may result in death.

Milk is highly nutritious to bacteria. Bacteria can quickly proliferate if their growth is not inhibited. Stopping the growth of bacteria in milk requires either heating to kill the bacteria, or chilling, which will not kill the bacteria but will slow down their growth.

E. coli, for instance, can go from ten cells to 100 million cells in just over six hours at 30°C. Only ten cells may be required to make someone ill. If such an organism is likely to be present, it’s important that any potential growth is stopped.

These harmful bacteria have caused outbreaks and disease associated with the consumption of raw milk in many countries. Data from the United States indicates that over a 13 year period to 2011, there were 2,384 illnesses, 284 hospitalisations and two deaths associated with the consumption of raw milk.

In Australia, raw milk contaminated by bacteria such as Campylobacter and Salmonella caused at least nine outbreaks of disease between 1997 and 2008, leading to 117 cases of illness.
So why do people choose to drink raw milk?

Advocates of raw milk often claim improved health benefit and nutritional value, or desiring a product which has not undergone further processing, retaining bacteria naturally present in milk.
But there is no evidence that the health benefits of milk are compromised by pasteurisation.

The defining difference between pasteurised and raw milk is the bacteria that are present. As soon as milk is secreted from the udder, it is at risk of contamination by many different bacteria as it makes its journey to our table. This includes harmful bacteria. These bacteria can lead to severe illness in humans, particularly children and the elderly.

For these reasons, raw milk continues to have a far higher risk of causing illness. Pasteurisation remains an important step in ensuring we can continue to enjoy safer, nutritious milk.

Further reading: Bath milk crisis must prompt better cosmetic safety regulation

Source: http://theconversation.com/explainer-what-is-raw-milk-and-why-is-it-harmful-35428

Health Check: does brain training make you smarter?

No one disputes that extensive training on a specific task will improve
performance on that task.  Paul Boxley.

Author: Jonathan Foster, Curtin Senior Fellow, Associate Professor & Clinical Neuropsychologist at Curtin University

No one who has kept their head out of the sand over the past several years needs to be told “brain training” is a hot topic. And it’s big business too, with advocates using claims such as “personal training designed by scientists” to market their wares.

Decades of studies in both laboratory animals and humans have demonstrated the capacity of the brain for some degree of plasticity. This can be extremely beneficial; after someone suffers a stroke, for instance, and has to relearn some basic abilities.

But is there any evidence that specific “brain training” can improve overall performance? Or is it all hype and hyperbole?

For many, not one

The cornerstone of scientific progress is the demonstration of evidence-based effects rather than a media vortex of gee-wizz findings in individuals, no matter how compelling these may be for the television viewer.

Sceptics argue that brain-training studies claiming to demonstrate significant effects lack more general applicability and have shown only very specific kinds of improvement.

Meanwhile, proponents of brain training argue studies failing to demonstrate effects employ flawed approaches, including unsatisfactory application of recommended methods.

The key question is generalizability of benefits – the holy grail of brain training.

The key question for assessing the benefits of brain 

training is the generalizability of benefitsDaniela Hartmann. 

No one really disputes that extensive training on a specific task will improve performance on that task. But the acid test for brain training is whether it can be reliably demonstrated that training on some tasks transfers more widely to a range of other tasks and thought processes.

In the largest study undertaken in this area to date, researchers were patently unable to demonstrate a generalisation of training across tasks.

They conducted a six-week online study in which 11,430 participants trained several times each week on cognitive tasks designed to improve reasoning, memory, planning, visuospatial skills and attention. Improvement effects were task specific and failed to transfer to other untrained tasks.

But in a more recent high-profile study undertaken in older individuals, another group of researchers used a video game in which players were required to drive and identify specific road signs.
After training, older individuals, aged 60 to 85 years, became more proficient than untrained individuals in their 20s. Their performance levels were sustained for six months, even without additional training.

Perhaps most critically, these researchers reported that older adults performed better at other attention and working memory tests as well, demonstrating the transferability of benefits from the training game to different cognitive functions.

But there’s been much criticism of the study’s findings; for example, with respect to the relatively small number of participants involved.

The bigger picture

And so it goes. Volleys are fired back and forth between the two camps against the backdrop of more general and far-reaching considerations that currently appear to stack up on the side of the sceptics.
It’s widely accepted among working scientists that it’s much more challenging to publish findings that demonstrate non-significant outcomes compared with findings that demonstrate statistically significant differences. So, there’s a potential publication bias against studies of brain training that fail to demonstrate an effect.

But where does this all leave us?

It may be that brain training will show generalizability only from some specific tasks onto others.
There have been claims, for instance, that brain training may improve intelligence (which remains an inchoate concept), or that brain training can rewire the prefrontal cortex or its connections – or both.
The latter (alluded to by researchers who did the video game study above) may be beneficial, given that prefrontal brain regions are known to be engaged in the coordination of many different processes.

It’s also been claimed from neuroimaging investigations that brain training can produce changes in the “hardwiring” of the brain. But whether these changes endure and what they truly signify remains open to question.

You could spend your time and money on
learning an instrument instead.Marco Tedaldi 

The jury is still out on brain training for otherwise healthy individuals. But if you’re considering taking it up, it’s important to consider that some of the principal proponents of brain training methods have a financial or other commercial stake in the packages they’re endorsing.

The key question you should ask yourself is the opportunity cost associated with brain training – what is it you are not doing in order to spend time “training your brain”?

In addition to financial expense, many brain-training packages involve considerable investment of your time over an extended period.

You might spend your time and money more effectively doing other things to improve your abilities, such as exercising, improving your diet, learning to play an instrument, or acquiring a new language.

These alternative pursuits confer the additional benefit of social interaction, which has clearly been demonstrated to benefit our brain health.

Source: http://theconversation.com/health-check-does-brain-training-make-you-smarter-18882

Explainer: nature, nurture and neuroplasticity

Neuroplasticity refers to the way in which the cells in the brain change in response to experience. Hey Paul Studios. Hey Paul Studios

Author: Anthony Hannan, Head of Neural Plasticity and ARC Future Fellow at The Florey Institute of Neuroscience and Mental Health


The human brain is the most complex and extraordinary structure in the known universe. And while there are many awe-inspiring facets of the brain, I will focus here on “neuroplasticity”, a term that has been bandied about a lot in the last couple of years.

Neuroplasticity refers to the way in which the cells in the brain (and other parts of the nervous system), change in response to experience. This is not simply a curious by-product of complex evolution but serves important functions such as learning, memory and response to brain damage.
Neuroplasticity is constantly occurring in both the developing and adult brain, but this article will focus on the adult brain and how some of the types of neuroplasticity affect the healthy and diseased brains.

Marvellous neuroplasticity

The human brain is thought to contain over 100 billion neurons interconnected by over a trillion synapses (the points of contact between neurons which transfer and store information). Over recent decades, it’s been shown that a key mechanism whereby we lay down new memories is via “synaptic plasticity”.

Changes occur in brain wiring, modifying the strength of connections between neurons. This form of neuroplasticity can involve adding or removing new synapses. If you remember anything you’ve read in this article, then you may have stored that new information in your brain via the formation of new connections between specific subsets of neurons.

Another form of neuroplasticity now known to occur in the brains of humans, and other mammals, is known as “adult neurogenesis”. It was thought for most of the 20th century that new neurons could not be born in the adult brain of mammals, such as humans. But part of the scientific revolution of brain research in recent decades has been the realisation that there are specific regions within the brain where neurons can be born throughout life.

Adult neurogenesis in a part of the brain called the hippocampus is thought to contribute to memory formation. In another part of the brain, the birth of new neurons is thought to contribute to our sense of smell.

This neuroplasticity gives the brain another of its many unique features, the fact that it never really ceases to develop. Indeed, the formation of new neurons and synapses in the adult brain constitutes a process of “microdevelopment”, which forms a continuum with the “macrodevelopment” of the embryonic and postnatal periods.

Neuroplasticity’s limitations

All of this neuroplasticity occurs in the healthy brain, so why can’t the brain repair itself following the onslaught of devastating brain diseases such as Alzheimer’s, Huntington’s, Parkinson’s and dementia? The implication is that the toxicity of these disease processes, due to both genetic and environmental factors, may overcome the brain’s capacity for self-repair and functional compensation.

But other brain disorders, such as stroke and traumatic brain injury, have revealed that neuroplasticity can occur in response to brain insults. Researchers have shown that substantial remodelling occurs to allow some recovery of function following a stroke, and can happen within hours of the event if the patient is encouraged to begin rehabilitation as soon as possible.

Research I’m involved in has shown that environmental enrichment, with increased levels of cognitive stimulation and physical activity, can delay disease onset and slow progression in a genetic model of the fatal inherited disorder, Huntington’s disease.

Prior to this work, Huntington’s had been considered the “epitome of genetic determinism”. But this discovery suggests there’s no such thing as a purely genetic brain disorder and that “exercising the brain” can influence or even delay the progress of a disease.

Therapeutic neuroplasticity

Our recent work is influencing the design of new clinical trials, with the demonstration that dementia and depression in Huntington’s can also be delayed by increased cognitive activity and physical exercise. Environmental enrichment has been found to be beneficial in models of schizophrenia and autism spectrum disorders, which involve abnormalities of brain development.

The findings show that neuroplasticity may be harnessed to delay onset, slow progression and possibly even reverse symptoms of various brain disorders.

One idea which has emerged from these experimental findings is that of “enviromimetics”. We are exploring the possibility of enviromimetics as a class of new drugs that mimic or enhance the beneficial effects of enhanced cognitive stimulation and physical exercise. No, not a drug that means you don’t have to exercise!

The idea is that these putative drugs would complement the beneficial effects of exercise and environmental stimulation. Enviromimetics could possibly achieve therapeutic effects via enhancement of neuroplasticity, thus providing a “brain boost” to help this extraordinary organ protect and repair itself.

These new discoveries in the field of neuroplasticity have implications for how each of us may protect our brain from the relentless weathering of ageing and disease. It’s known that lifestyle factors that are good for the body, such as regular physical exercise and a healthy diet, are also beneficial for the brain. And those who keep their brains stimulated with regular complex mental activities (such as reading The Conversation and conversing) may also help delay onset of common brain diseases, such as Alzheimer’s and dementia.

The harsh reality of life is that we are each dealt a genetic deck of cards at conception, which we can do nothing about. However, our growing knowledge of neuroplasticity demonstrates that we can all engage in healthy lifestyles to help protect our brains. Neuroscientists are now attempting to develop new therapies to enhance neuroplasticity, to combat the enormous and expanding burden of brain and mind disorders.


Source: http://theconversation.com/explainer-nature-nurture-and-neuroplasticity-10734

How to protect your skin while getting enough vitamin D

 

 

 

Author: Terry Slevin, Honorary Senior Lecturer in Public Health at Curtin University; Education & Research Director, Cancer Council WA; Chair of the Occupational and Environmental Cancer Committee at Cancer Council Australia

 

 

It’s been more than 30 years since Sid Seagull first urged us to slip, slop and slap while out in the sun. But while we’ve made enormous progress fighting skin cancer, melanomas.

It’s been more than 30 years since Sid Seagull first urged us to slip, slop and slap while out in the sun. But while we’ve made enormous progress fighting skin cancer, melanomas are still the fourth most common cancer in Australia and one of the most deadly. Add to the the huge burden of non-melanoma skin cancer.

From Cairns to Hobart, Brisbane to Perth and all points between, the UV Index will reach the “extreme” range most days this summer.

So how can you protect your skin while getting enough of the sunshine-derived vitamin D?are still the fourth most common cancer in Australia and one of the most deadly. Add to the the huge burden of non-melanoma skin cancer.

From Cairns to Hobart, Brisbane to Perth and all points between, the UV Index will reach the “extreme” range most days this summer.

So how can you protect your skin while getting enough of the sunshine-derived vitamin D?

Benefits and harms of ultraviolet radiation

While limited dietary sources of vitamin D are available, exposure to ultraviolet radiation (UVR) is the most effective source of vitamin D for the majority of the world’s population.

Vitamin D deficiency is unquestionably linked to compromised bone health. While levels of evidence vary, it is also associated with a wide range of other potential health problems.

On the other hand, excess UVR exposure is strongly linked to increasing risk of skin cancer.

To confuse the issue further, a recently published paper suggested sun exposure might help reduce blood pressure and influence heart disease risk. But not through vitamin D. This research is still in its early days, but it may be that some of the benefits previously ascribed to vitamin D occur through other mechanisms related to sun exposure.



Getting enough vitamin D and protecting your skin is all about balance. CC BY-NC-SA



 

How much is enough?

Active debate continues about where cut points for deficiency and sufficiency should be drawn.
Serum levels of 25-hydroxy vitamin D (also called 25-OHD) are used to measure vitamin D adequacy. The Institutes of Medicine (IOM) 2011 report recommended deficiency be defined as 25-OHD less than 30 nanomoles per litre nmol/L and adequacy as 50 to 125 nmol/L.

The range of 30 to 50nmol/L is defined as “insufficient”, indicating some health risk to some but not all individuals. The report advises:

Use of higher than appropriate cut-points for serum 25-OHD levels would be expected to artificially increase the estimates of the prevalence of vitamin D deficiency.

The level of UVR exposure necessary to establish and maintain optimum levels of vitamin D varies across the world. It is influenced by geography, season, age, skin type and more. However, in higher UVR locations like ours, minimising UVR exposure during summer, and in particular in high UVR times of the day, remains a health priority.

How many of us struggle to get enough?

This is an age-old question. Of course, the answer depends on the definition of what is enough. The Australian Bureau of Statistics reported in April this year on 25 D measures taken from the National Health Survey in 2011/12 that:

Just under one in four (23%), or four million adults, had a vitamin D deficiency, which comprised 17% with a mild deficiency, 6% with a moderate deficiency and less than 1% with a severe deficiency.

The cut points and definitions are crucial. Australian researchers Robyn Lucas and Rachel Neale propose a different presentation of those data:

However these data are analysed, it is clear that about three-quarters of us have perfectly adequate levels of vitamin D.

By one interpretation, there are similar proportions of us who may have too much (which may contribute to some disease states) as have too little (which undoubtedly contributes to bone health problems).

As for the “vitamin D twilight zone” – levels of between 30 and 49nmol/L – Lucas and Neale question whether there are any adverse health effects at all. “It may be normal in mid to late winter. It may be a concern in late summer,” they say.

In May, 700,000 vitamin D were tests carried out in Australia. More than four million tests were done in the last financial year. This cost A$145 million, of which about A$98 million (two-thirds) was the cost of the test for women.

As a result of this burgeoning cost, changes were made to the Medicare Benefits Schedule, so only high-risk patients will get a rebate when they get vitamin D levels screened. Eligible patients include those with deeply pigmented skin, osteoporosis or those with chronic lack of sun exposure.

What should we do?

So what does make sense when it comes to sun exposure, skin cancer and vitamin D? The trick is, of course, getting the balance right and avoiding extremes, in one direction or the other.

Adjusting sun exposure according to the time of year and time of day is important. The UV Index will be in the extreme range in the middle of the day through most, if not all, of summer. So avoiding exposure for the few hours in the in the middle of summer days is smart. The World Health Organization recommends sun protection once the UV Index reaches or exceeds three.

Protect your skin during peak UV times. Alex Liivet/Flickr, CC BY

Skin type and geography are the other key factors: darker skin, a little more; lighter skin, a little less; further north, less exposure; further south, a little more.

People in special circumstances – who are immobile or infirm, or who routinely cover their skin for cultural or other reasons – should talk to their doctor about vitamin D.

Depending on where you live, five minutes of mid-morning or mid-afternoon sun two to three times a week – and certainly avoiding any sun burning – is a helpful rule. But it’s best to keep the head, face and neck protected as they get lots of sun and are at highest skin cancer risk.

Terry Slevin is editor of Sun, Skin and Health, CSIRO Publishing.

Source: http://theconversation.com/how-to-protect-your-skin-while-getting-enough-vitamin-d-34143

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