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Wednesday 29 August 2012

4 cups of coffee a day 'protects against bowel cancer'

reposted from: http://www.nhs.uk/news/2012/08august/Pages/Coffeee-protects-against-bowel-cancer.aspx
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Participants who drunk six or more cups a day had a 39% reduction in risk 

‘Six cups of coffee a day could cut the risk of bowel cancer by 40 per cent’ the Daily Mail explains, while The Daily Telegraph points out that just ‘four cups a day’ leads to a 15% rate of reduction.
The news follows a long-term study that tracked the behaviour and associated health outcomes (cohort study) of just under half a million Americans over the course of 10 years.
At the start of the study participants completed questionnaires on their diet and lifestyle and during the follow-up period the researchers looked at the number of colorectal cancers (commonly known as bowel cancer) that developed.
Those who drank four to five cups of coffee (caffeinated or decaffeinated) a day had a 15% reduced risk of developing cancer, while those who drank six or more had a 26% reduced risk, compared with non-drinkers.
Sadly for tea drinkers, there was no reduction in bowel cancer risk, but being a US study, the number of tea drinkers was relatively small.
This was a well conducted study that does suggest a link between coffee consumption and reduced bowel cancer risk. However, the researchers did recommend that further investigation into the link is needed, including study of the specific chemicals in coffee that could be having an effect.
It should be noted that caffeine is a stimulant, and drinking excessive amounts of it can lead to unwanted side effects, such as restlessness, insomnia and dehydration.
There are more well established methods of reducing your risk of bowel cancer such as taking regular exercise, eating a healthy diet and quitting smoking.

Pregnancy and breastfeeding

If you are pregnant then it is recommended that you drink no more than 200mg of caffeine a day (roughly two mugs of instant coffee), as higher levels than this have been linked to complications such as miscarriage and low birth weight.
You should also avoid drinking caffeine if breastfeeding as it can pass into your breast milk which can make your baby irritable and cause sleeping problems.

Where did the story come from?

The study was carried out by researchers from the US National Cancer Institute and Imperial College, London, and was funded by the Intramural Research Program of the US National Cancer Institute.
The study was published in the peer-reviewed American Journal of Clinical Nutrition.
The media is generally representative of this research, though they do not spell out some of the inherent limitations of a cohort study. This is important as it means that it is difficult to say whether a direct link exists between coffee consumption and bowel cancer risk. There may be other unidentified lifestyle factors that contributed to bowel cancer risk.
Some news stories also report the study’s finding that tea had no effect on cancer risk, without mentioning that few heavy tea drinkers were included in the study.
The advice from the Daily Express – supposedly from an ‘unnamed’ bowel cancer charity – that you should ‘consult your GP about coffee drinking first’ seems a little bizzare. In the absence of any serious health conditions you probably don’t need to check with your doctor if it is okay to drink four cups of coffee a day.

What kind of research was this?

This was a cohort study – the National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study – which assessed various aspects of diet and lifestyle and has followed participants for a number of years looking at various health outcomes. This particular study examined information on coffee consumption which was collected at the start of the study, and looked to see how this related to the development of colorectal cancer.
Such a cohort study can demonstrate associations, but it cannot prove cause and effect as there may be other unmeasured factors that are associated with both coffee drinking and bowel cancer risk and so underlie the observed link. Also, self-reported coffee consumption at one point in time may not be a reliable measure of longer term patterns. The ideal way to investigate the effects that dietary factors have upon a specific health outcomes would be a randomised controlled trial (RCT). However, an RCT of this type is arguably not feasible due to a number of factors, such as:
  • time
  • expense
  • adherence (making sure people are not drinking too much or to little coffee)

What did the research involve?

Between 1995 and 1996 the NIH-AARP Diet and Health Study recruited AARP members, aged between 50 and 71 years old, from eight areas in the US. This study included 489,706 participants.
At the start of the study, participants completed a questionnaire which included information on sociodemographics (factors such as occupation and income), as well as:
  • diet
  • body measures
  • lifestyle (such as physical activity and smoking)
This questionnaire included a 124-item food frequency questionnaire, which included information on intake and portion sizes over the past year. The researchers used the results of the questionnaire to classify people according to their coffee and tea intake. Coffee intake was split into six categories as follows:
  • none
  • less than one cup a week
  • one cup a day
  • two to three cups a day
  • four to five cups a day
  • six or more cups a day
Tea was assessed in five slightly different categories:
  • none
  • less than one cup a month
  • one to three cups a month
  • one to six cups a week
  • at least one cup a day
Tea and coffee intake were also classified depending on whether the coffee or tea was caffeinated or decaffeinated more than half of the time. The researchers further validated their assessments by carrying out two, 24-hour dietary assessments of a sample of 1,953 participants. This assessment included information on whether the coffee was ground, instant or espresso.
Cancer cases were identified through linking to state cancer registries, which included codes for the specific type of cancer. Participants were followed for an average of 10.5 years to the end of December 2006.
The researchers analysed the association between tea and coffee intake and the development of cancer. In their analyses they adjusted for various potential confounding factors, including:
  • sex
  • age
  • education
  • smoking
  • diabetes
  • physical activity
  • body mass index (BMI)
  • red-meat consumption (a diet rich in red meat is a known risk factor for bowel cancer)
  • fruit and vegetable consumption (a diet rich in fresh fruit and vegetables can reduce bowel cancer risk)
  • alcohol intake
  • the use of hormone replacement therapy (HRT) in women

What were the basic results?

There were 6,946 new cases of colorectal cancer during the 10.5 years of follow-up. In the baseline assessments, approximately 90% of the cohort drank coffee, and 16% reported drinking four or more cups a day.
  • Compared with non-drinkers of coffee, those who drank four to five cups a day had a 15% reduced risk of developing colorectal cancer (hazard ratio 0.85; 95% confidence interval (CI) 0.75 to 0.96).
  • Compared with non-drinkers of coffee, those who drank six or more cups a day had a 26% reduced risk (hazard ratio 0.74, 95% confidence interval 0.61 to 0.89).
  • There was no significant association between coffee and cancer for those who drank three or fewer cups a day (neither increased nor decreased risk).
  • When they split into caffeinated and decaffeinated coffee, the only significant associations were a 17% decreased risk for those who drank six or more cups of caffeinated a day, and a 21% decreased risk for those who drank four to five cups of decaffeinated a day.
  • No significant associations were observed according to categories of tea intake. However, the majority of participants did not drink tea, with 62% of participants reporting no tea consumption at baseline.

How did the researchers interpret the results?

The researchers conclude that in their large US cohort, coffee consumption was inversely associated with colorectal cancer (that is, as intake goes up, risk goes down).

Conclusion

This study finds an association between coffee drinking and bowel cancer risk, and benefits from its large sample size and thorough follow-up of outcomes. It does, however, contain important limitations:
Reduction of risk was only seen at high levels of coffee consumption
The results don’t give a clear message about the effects of caffeinated or decaffeinated coffee. The only significant associations observed were for six or more cups of caffeinated coffee a day (but not for four to five); and for four to five cups of decaffeinated coffee a day (but not for those who drank six or more cups). All other risk associations were non-significant. Such seemingly random significant results makes it questionable whether these could be chance associations.
When looking at coffee overall (both caffeinated and decaffeinated) the only risk reductions observed were for those who drank either four to five or six or more cups a day

These groups of very high-levels of coffee consumers actually represented a small minority of the people actually taking part in the study. And the smaller the numbers detected by researchers (the sample size), the more likely it is that any effect detected by the researchers could be the result of chance.
Possible inaccuracies in reported coffee consumption
Coffee consumption was self-reported at one point in time only. This may not be a reliable measure, and may not be representative of longer term patterns. Also, specific information on the type of coffee consumed was only gained from the small subset of participants who completed the 24-hour recall.
As the researchers confirm, no information was taken on factors on such as:
  • the type of coffee bean
  • how the coffee was brewed
  • the amount of caffeine found in caffeinated coffee
It is also worth noting that although they found no association between tea-drinking and bowel cancer, there were few heavy tea drinkers in the cohort. So it is difficult to give a true assessment of the effects of tea drinking (again with a small sample size the potential protective effects of heavy tea drinking could be ‘scrambled’ by the effects of chance).
 
In addition, the researchers collected no information on the type of tea drunk, and therefore this category included a range of tea types, including ‘normal’, herbal, and green teas.
Possibility that other factors underlie the association
The research demonstrates an association between coffee drinking and bowel cancer risk, but it cannot prove causation. Though the researchers have made careful attempts to adjust for many other risk factors for bowel cancer that may be involved in the relationship, it is still possible that there are other, unmeasured factors, that are associated with both coffee drinking and bowel cancer risk and so underlie the observed link. As a purely theoretical example, it could be the case that drinking decaffeinated coffee has no direct preventative effect. However, people who do drink ‘de-caff’ tend to be more health conscious, eat a healthier diet and exercise more – and this could lead to the reduction in risk.
It is always difficult to specifically take into account all the different aspects of a person’s diet and lifestyle.
May not apply to other population groups
This was a study of retired US citizens, who were predominantly white and well-educated. The findings may not apply to people of younger age groups, or in other countries where different society and environmental factors may influence both their coffee consumption and cancer risk.
Further research is needed
As the researchers acknowledge, further investigation into the link is needed, in particular looking at the specific chemical constituents of coffee that could be having an effect.
For now, it is important to consider that it is alright to consume most things in moderation. Caffeine is a stimulant, and drinking excessive amounts can give other unwanted side effects. Anyone wanting to reduce their risk of cancer should ensure that they consume a healthy diet, take exercise, and stop smoking.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links to the headlines

'Coffee could protect against bowel cancer'. The Daily Telegraph, August 28 2012
'Four Coffees A Day Can Cut The Risk Of Cancer'. Daily Express, August 29 2012

Links to the science

Sinha R, Cross AJ, Daniel CR, et al. Caffeinated and decaffeinated coffee and tea intakes and risk of colorectal cancer in a large prospective study. American Journal of Clinical Nutrition. Published online, June 13 2012

Saturday 25 August 2012

IGF-1 levels

reposted from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774752/
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"Moreover, in monkeys (and by extension, humans) some benefits of dietary restriction, such as low IGF-I levels, may decrease cancer risk, but also increase the risk of osteoporotic fractures 35. Thus, it might be necessary to reduce IGF-I signalling during early adulthood to prevent cancer, but increase it at older ages to prevent non-cancerous diseases 36."

Role of the GH/IGF-1 axis in lifespan and healthspan: lessons from animal models

Role of the GH/IGF-1 axis in lifespan and healthspan: lessons from animal models

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"Consistently, two interventions, caloric restriction and repression of the growth hormone (GH)/insulin like growth factor-1/insulin axis, have been shown to increase lifespan in both invertebrates and vertebrate animal model systems. Caloric restriction (CR) is a nutrition intervention that robustly extends lifespan whether it is started early or later in life. Likewise, genes involved in the GH/IGF-1 signaling pathways can lengthen lifespan in vertebrates and invertebrates, implying evolutionary conservation of the molecular mechanisms. Specifically, insulin and insulin-like growth factor 1 (IGF-1)-like signaling and its downstream intracellular signaling molecules have been shown to be associated with lifespan in fruit flies and nematodes. 
More recently, mammalian models with reduced growth hormone (GH) and/or IGF-1 signaling have also been shown to have extended lifespans as compared to control siblings. Importantly, this research has also shown that these genetic alterations can keep the animals healthy and disease-free for longer periods and can alleviate specific age-related pathologies similar to what is observed for CR individuals. Thus, these mutations may not only extend lifespan but may also improve healthspan, the general health and quality of life of an organism as it ages.

Role of the GH/IGF-1 axis in lifespan and healthspan: lessons from animal models

Role of the GH/IGF-1 axis in lifespan and healthspan: lessons from animal models

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Control of aging and longevity by IGF-I signaling. [Exp Gerontol. 2005] - PubMed - NCBI

Control of aging and longevity by IGF-I signaling. [Exp Gerontol. 2005] - PubMed - NCBI

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"Abstract: Animal models have established the IGF-I signaling pathway as a key modulator of aging in rodents and invertebrates. Considerable evidence suggests that reduced exposure of tissue to IGF-I is associated with an extended lifespan in these species.
In humans, IGF-I is linked to various age-related diseases that are limiting factors for youthful longevity. On one hand, reduced IGF-I activity is associated with significant morbidity in adulthood with an increased risk of developing cardiovascular disease, diabetes, osteoporosis and neurodegenerative diseases.
On the other hand, elevated IGF-I levels have been linked to cancer risk given the role of IGF in mediating normal and malignant tissue growth.
Thus, IGF is clearly involved in modulating disease of aging; however, the mechanism appears to be complex and interdependent on additional modulating factors.
It is attractive to hypothesize that maximal human survival depends on tight regulation of the GH-IGF axis and maintenance of optimal IGF-I action in order to prevent morbidities associated with either deficient or excessive state. Specifically, it is possible that lower levels of IGF-I during early adulthood followed by higher levels of IGF-I later in life may be most beneficial for human longevity by addressing age-specific morbidities."

Potentially conserved pro-ageing pathways, their interconnections and possible targets for intervention

PubMed Central, Figure 1: Nature. 2008 August 28; 454(7208): 1065–1071. doi: 10.1038/nature07216 from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774752/

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In this very simplified depiction, three main pathways, the IIS (insulin/insulin-like growth factor 1 (IGF-I) signalling) pathway, TOR and mitochondrial pathway, are indicated.

The pro-ageing activities of these pathways are conserved across species, with energy sensors, such as AMPK, as potentially important hubs in the complex networks that integrate them.

However, it is important to note potential dissimilarities among species as well. Most, if not all, defects in the mitochondrial respiratory chain are lethal or cause disease in humans, but can increase lifespan in nematodes or yeast. In mammals, mitochondria play an important part in signalling apoptosis, which can either drive or retard ageing, depending on the cell type.

There is evidence that many longevity signals converge on members of the FOXO and sirtuin protein families, which can interact. Effects of FOXO and SIR2 in cells can be either beneficial (for example, increasing antioxidant defence) or detrimental (for example, apoptosis), and may or may not promote organismal survival. Apoptosis can be beneficial, for example, by eliminating damaged cells and preventing cancer, or can be detrimental, by eliminating irreplaceable cells, such as neurons.

Thursday 23 August 2012

Statins for all by the age of 50 years? : The Lancet

Statins for all by the age of 50 years? : The Lancet


Shah Ebrahim, Juan P Casas
In The Lancet , the Cholesterol Treatment Trialists' (CTT) Collaborators report a relative risk reduction on statins of about 20% (RR 0.79, 95% CI 0.77—0.81) for major vascular events per 1 mmol/L reduction in LDL cholesterol across different levels of cardiovascular risk. Men and women, old and young, and people with and without cardiovascular disease all benefit. These findings confirm the efficacy of statins for primary prevention, resolving concerns about possible serious adverse effects and p ..

Wednesday 22 August 2012

biomarker tests for CR diet

reposted from: http://www.crsociety.org/resources/tests_and_biomarkers
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Lists biomarker tests for CR diet.

Aspirin: Experts reveal who should be taking aspirin every day | Mail Online

Aspirin: Experts reveal who should be taking aspirin every day | Mail Online

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Mark P. Mattson talks about Intermittent Energy Fasting

reposted from: http://mpegmedia.abc.net.au/rn/podcast/2012/05/hrt_20120507_1740.mp3 via https://twitter.com/DrMichaelMosley# 17th August 2012

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Prof. Mark P. Mattson (ChNat. Inst. Ageing in Baltimore): CR in animals reduces cancer, kidney disease, diabetes - all animals live longer. Animals in wild are geered to feast or famine so the human 3 meals a day is abnormal from evolutionary standpoint. Intermittent energy restriction (IER) (eg 2 days a week have low calorie intake) imitates evolution. IER v daily CR (calorie restricted every day): IER has more powerful effects for nerve cells to resist stress and disease.

With IER before animals become symptomatic can protect brain: reduces Amyloid accumulation (gunk ceases up the brain) of Alzheimers disease and preserves dopamine producing neurons which reduces Parkinsons disease. On alternate Day Fasting, before symptoms become symtomatic, mice live 30% longer on IER.

IER reduced Oxidative stress (reduces rusting of brain ie reduced free radicals), reduced local inflammation (reduced cytokines eg tumour necrosis factor TNF - immune system less active so brain ages less).

Fasting increases production of protein neurotrophic factors (causes nerve cells to grow), increases stem cell Brain Derived Neurotrophic Factor (BDNF wiki) which increases production of nerve cells (neurogenesis). With increased exercise AND IEF, BDNF:-

  1. Strengthens neuron synapses - maintains cognitive function
  2. Increases antioxidant enzymes (counteract free radicals), suppresses free radicals and inflammation

Muscle Analogy

This increase in stress in your brain is analogous to exciting muscle cells which make them stronger and contract. Nerve cells when exited send signal to next neuron, become more active when they are hungry.  With mild stress - nerve cells become more active and this is evolutionary important.

Downside of IER 

Reduced wound healing, increased risk of infection for cave men ancestors.

Human Trials

In breast tumour patients (with Michelle Harvie, Wythenshawe Hospital, Uni Manchester reported by Daily Mail), Press Release, full article Int. Journal of Obesity. 100 subjects split into 3 groups. 1) control diet ate normally, 2) 15% reduction in calories (CER) 3) 5:2 day fast diet (IER) - had less insulin resistance than other groups.

IER and CER are equally effective for weight loss, comparable reductions in: leptin, C-reactive protein, total and LDL cholesterol, triglycerides, blood pressure, increased IGFBP-1 and IGFBP-2, negligible changes in total and free IGF-1.

on IER:-
  1. sugar reaching breast cells decreased 
    1. breast cells divide less frequently, reducing chances of cancer
  2. had fewer cancer-causing hormones in their blood six months later 
    1. Leptin fell by 40 per cent 
    2. Insulin fell by 25 per cent
    3. C-Reactive Protein fell by 15 per cent

Thursday 16 August 2012

Egg Yolks study

reposted from: http://www.nhs.uk/news/2012/08august/Pages/Eating-egg-yolks-as-bad-as-smoking.aspx
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"Eating egg yolks is as bad as smoking in speeding up coronary heart disease" the Daily Mail says, reporting that egg yolks contribute to the clogging up of arteries which, in turn, can increase the risk of heart disease.
The news is based on a Canadian study which used ultrasound to look at the fatty build-up in the arteries of around 1,200 adults who were attending a clinic because they had pre-existing risk factors for heart disease.
The adults were questioned on their smoking history, the number of egg yolks eaten per week and how long they had eaten this amount of egg yolks.
They found that a combination of smoking and egg yolk consumption was related to a fatty build-up in the arteries, which could increase the risk of heart disease as well as other conditions that can affect the heart and blood vessels (cardiovascular diseases or CVDs).
This study does contain some important limitations, such as:
  • the accuracy of the participants’ recollections of their egg yolk consumption
  • a lack of detailed information on how the eggs were cooked
  • there may have been additional risk factors contributing to artery ‘clogging’, not assessed by the study, such as lack of exercise or alcohol consumption
  • while it is reasonable to assume that fatty build-up in the neck arteries can increase the risk of heart disease, it is uncertain exactly what the increased level of risk would be
This study perhaps best supports the notion of “all things in moderation”. Eggs are a good source of protein. Without further study, there is no firm evidence that egg yolks are as bad for you as smoking.

Where did the story come from?

The study was carried out by researchers from the Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, and other research institutions in Canada and was funded by the Heart & Stroke Foundation of Ontario.
The study was published in the peer-reviewed medical journal: Atherosclerosis.
While the Mail reports that eating egg yolks is two-thirds as bad for you as smoking when it comes to artery build-up, this cannot be concluded when you consider the limitations of this single piece of research. Also, the headline does not make it clear that the researchers were only looking at people with pre-existing risk factors for heart disease and not the population at large.

What kind of research was this?

The authors report that although high cholesterol contributes to heart disease, there is a general lack of consensus on whether eggs actually raise blood cholesterol and contribute to heart disease.
This study aimed to examine whether egg yolk consumption was related to the fatty (plaque) build-up in the arteries of a consecutive series of adults attending a vascular clinic in Canada.
The design of this study includes several limitations:
  • it recruited a small, selective sample of adults
  • egg yolk consumption is being estimated through questionnaire responses which may contain inaccuracies
  • other factors not studied by the researchers, such as less exercise or a diet higher in other saturated fats, may also contribute towards a build-up of plaque

What did the research involve?

The observational study included 1,231 consecutive patients (average age, 62) referred to a vascular prevention clinic at a hospital in Canada. The total plaque area of their carotid arteries (the main arteries in the neck supplying blood to the head) was measured by ultrasound scan. At the time of referral lifestyle information was also measured by questionnaire. This included smoking history and the frequency of egg yolk consumption. From these responses the researchers calculated:
  • pack-years of smoking: the number of packs of cigarettes per day multiplied by the number of years of smoking
  • egg-yolk years: the number of egg yolks per week multiplied by the number of years consumed
The researchers specifically say that they did not assess:
  • alcohol intake
  • exercise taken
  • liquorice consumption (high intake of liquorice can increase blood pressure and cause problems in people with heart disease)

What were the basic results?

Overall the researchers found that, as would be expected, the extent of plaque build-up in the carotid arteries increased with age. They also found that both increased smoking and increased egg yolk consumption were associated with more plaque build-up.
Average plaque area in the carotid arteries of patients consuming less than two eggs per week (388 people) was 125mm2 compared to 132mm2 in those consuming three or more eggs per week (603 people). This was a statistically significant difference (not the result of chance).
The association was not affected by adjustment for age.
The researchers did additional analysis adjusting for other cardiovascular risk factors, such as:
  • sex
  • total blood cholesterol
  • blood pressure
  • diabetes
  • body mass index (BMI)
  • smoking
The researchers do not give figures for the build-up in the arteries associated with smoking, but say that the increase in total plaque area with increasing egg consumption followed a similar, linear pattern to that of cigarette smoking.
The highest consumption of eggs (eating more than 200 yolks per year) was said to be equivalent, in terms of plaque build-up, to two thirds of the effect of the highest amount of smoking – the figure quoted by the Mail.

How did the researchers interpret the results?

The researchers say that their findings suggest that regular consumption of egg yolk should be avoided by people at risk of cardiovascular disease. They do acknowledge though, that their theory should be tested in a prospective study that includes more detailed information about diet and other possible confounding factors, such as exercise and waist circumference.

Conclusion

This study found that egg yolk consumption was associated with increased fatty build-up in the arteries of the neck, though this was small when compared to the build-up expected with age. This study has important limitations which mean that it cannot be concluded that egg yolks are as bad for you as smoking:
  • Average egg yolk consumption per week and duration was evaluated through a questionnaire response. These are only estimates and may include a considerable degree of inaccuracy. Consumption may vary over time. We also don’t know how these eggs were prepared (boiled, fried in oil, scrambled in butter, etc).
  • This wasn’t a trial, and so people are choosing the number of egg yolks they eat. People who ate more egg yolks may differ in other health and lifestyle factors from people who ate less, and this may account for their different artery build-up. For example, as the researchers rightly acknowledge, they did not thoroughly assess other dietary factors, exercise or waist circumference. It is possible that higher egg yolk consumption could be associated with less exercise and higher overall saturated fat intake – both well known risk factors for heart disease. The small changes in fatty build-up in the arteries seen with higher egg yolk consumption could have been accounted for by these other factors.
  • None of the participants in this study were reported to be suffering from heart disease and the heart arteries were not examined.
  • We do not know how or whether the extent of fatty build-up in the neck arteries was associated with build-up in the heart arteries.
  • This is a relatively small, select sample of people attending a vascular clinic in Canada, and further quality studies would be needed to better assess the question.
This study perhaps best supports the notion of all things in moderation. Eggs are a good source of protein in addition to other vitamins and minerals and most experts advise that they can form part of a healthy, balanced diet.
If you have been told you have pre-existing risk factors for heart disease, or other CVDs, your GP will be able to provide more detailed advice about a recommended diet. 
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.







Links to the headlines

Links to the science

Spence D, Jenkins DJA, Davignon J. Egg yolk consumption and carotid plaque. Atherosclerosis. Published online July 31 2012

Wednesday 15 August 2012

Patrick Holford on Michael Mosley 'Eat, Fast & Live Longer"

reposted from: http://www.patrickholford.com/index.php/blog/blogarticle/1237/
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Posted Tuesday, August 07, 2012
Patrick Holford says inter alia ...


Readers of my newsletter, or latest book Ten Secrets of Healthy Ageing will be familiar with the reasons behind the benefits of modified fasting, which lowers blood sugar levels and insulin production. This, in turn, reverses metabolic syndrome and burns fat. The Horizon programme emphasized the need to bring down levels of insulin-like growth factor (IGF-1) to extend life and reduce disease risk. In Issue 55 I explained in detail how IGF-1 is associated with disease risk and, in Issue 61, why it is critical for health to keep insulin down. Horizon recommended eating less protein to bring down IGF-1, but failed to mention that the biggest promoter is dairy products. This is why my low-GL diet, which is specifically designed to keep insulin down, includes very little meat or dairy products.

If your goal is to live long and be healthy it’s better to have lower IGF-1 levels, achieved by eating a more plant-based, less meat and dairy based diet. The key is to keep blood sugar levels stable, which means less insulin release. These are the key principles in my low GL diet.


Emma Rourke reviews Horizon: Eat, Fast, and Live Longer

reposted from: http://blogs.bmj.com/bmj/2012/08/14/emma-rourke-reviews-horizon-eat-fast-and-live-longer/
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14 Aug, 12 | by BMJ Group

There’s a new intervention being trialled. It will help you lose weight, it will delay the potential onset of dementia, and best of all it will enable you to live in the fullest of health for longer. Perhaps the main virtues of this intervention centre on its sheer simplicity: it doesn’t involve putting any chemicals into your body, it doesn’t involve surgery, and it doesn’t cost anything—it may even save you money. All you have to do is deprive yourself of one of life’s great pleasures—food.
The BBC aired Horizon: Eat, Fast and Live Longer earlier this week. During this one hour programme, Michael Mosley visits a number of institutions seeking to understand the ageing process. He meets a variety of experts, all of whom extol the virtues of caloric restriction (CR), and tries methods they advise in attempts to improve his performance on physiological testing. The most extreme of these methods involved 3 days and 4 nights of fasting, wherein Mosley consumed only water, black tea, and a single sachet of powdered soup.  Subsequently, he tried alternate day fasting, where consumption is limited to around 500 calories on one “fast” day and completely unlimited the following “feed” day. He finally settled for a 5 day “feed” period followed by a 2 day 500 calorie fast period.
For a supposedly scientific programme, however, the science was rather scant. The focus was strongly on the insulin-like growth factor 1 (IGF-1) as mediator of the benefits of CR. This signalling pathway has been widely studied and is known to stimulate growth and inhibit apoptosis of cells. Perhaps unsurprisingly given this role, it has been implicated in the pathogenesis of cancer [1]. It has several key functions in the body, including growth and maintenance of the skeletal system [2]. Interestingly, in vivo deficiency of IGF-1 in combination with testosterone correlates with reduced survival [3].
CR (without malnutrition) has been shown to increase lifespan in laboratory animals. In rodents, for example, CR postpones onset of age-related pathology and prolongs lifespan [4]. Is this explained solely by IGF-1 levels? Studies have sought to test the popular oxidative stress theory of ageing, and indeed noted reduced markers of oxidative damage in calorie restricted rodents [4]. This alternative mechanism by which CR may affect ageing is not even touched upon by the programme. As with much human science, it is more complicated than it seems and there is still no consensus on the role of antioxidant levels in CR—there’s something else at play [4]. That something may involve the nutrient-sensing pathways of target of rapamycin (TOR), it may involve the forkhead transcription factor (FOXO), and it may involve sirtuins [5]. In fact, the one thing we can be sure about is that the molecular determinants of lifespan are incredibly complex, and far from fully understood [6].
The programme furthermore neglected many social factors complicit in the ageing process. Humans are not laboratory animals and their environment cannot be so strictly controlled. Nevertheless, somewhat controversial experimentation in humans is ongoing. Accordingly, some may question whether it is responsible for a qualified doctor to so emphatically endorse such an approach in a prime time television slot? “This could radically transform the nation’s health,” he says.
The programme was littered with health warnings—“don’t do this without supervision” and “for some fasting can be dangerous”—but within hours online weight loss forums were overflowing with posts from people saying they’d give it a go. Mosley’s wife, a GP, appears to support his desire to pursue a 5 days feeding 2 days fasting regime, thus reinforcing to the public that this is a safe and worthwhile method.
Perhaps the diet Mosley ultimately adopts is not that radical, and perhaps it doesn’t even represent CR (the level at which CR is defined varies from 10-25% reduction in overall calorie intake in humans). Any attempt to encourage reduced calorie intake in a nation with such high rates of obesity as our own may be commendable, but critics will likely find little new in the advice Mosley dishes out: reduce your calorie intake, reduce your weight, reduce your cardiovascular risk factors. Perhaps that’s the message to hope people take forward from this.
References:

More exercise in your 50s 'cuts heart disease risk'

reposted from: http://www.nhs.uk/news/2012/08august/Pages/Never-too-late.aspx via Netvibes
crabsallover highlightskey pointscomments / links.

Tue Aug 14, 2012 10:32 
"Exercise in midlife protects heart," says BBC News, while the Daily Mail tells us that "gardening, walking and DIY in your fifties can cut risk of heart disease".
The news is based on a large study looking at the health of middle-aged people. Researchers found that those who met physical activity recommendations of at least 2.5 hours of moderate to vigorous exercise a week had lower levels of inflammation in their body compared with people who did not get enough exercise.
Reducing levels of inflammation is important as persistent inflammation, even at relatively modest levels, is thought to contribute to the adverse effects of ageing. For example, it is thought to contribute to loss of muscle power and strength, cardiovascular disease or CVD (conditions that affect the heart and blood vessels) and depression.
Interestingly, the results were independent of body fat. This suggests that exercise was still of significant benefit for people with no, or little, previous history of exercise.
The study had some limitations, including the fact that it measured markers of inflammation rather than CVD rates themselves. Nevertheless, this was a well conducted study that reinforces the health benefits of even moderate exercise.

Where did the story come from?

The research was part of the Whitehall II study ... The study was published in the peer-reviewed journal Circulation.
This story has been covered by the BBC, The Daily Telegraph and the Daily Mail. The news coverage was accurate.
The media coverage of the study focused on the fact that the average age of the participants was almost 50. However, although this was the case, the study did not address when in your life exercise is the most beneficial. The Department of Health recommends that all people, whatever their age, take part in regular physical activities.

What kind of research was this?

This was a prospective cohort study that aimed to examine the association between long-term physical activity behaviour and low-grade inflammation over a 10-year follow-up period.
Although a cohort study was the appropriate study type to investigate the association between exercise and inflammatory markers, it cannot prove that exercise directly caused the differences.
randomised controlled trial (RCT) with a long follow-up would be required to show direct cause and effect (causation). However, such a trial would be unethical to perform as people in a control group who were told not to exercise could damage their health.

What did the research involve?

Participants were part of the Whitehall II population-based cohort, which aimed to investigate social and occupational influences on cardiovascular disease risk. This study used data from 4,289 men and women who were recruited from the British civil service, who were 49 years old on average.
These people answered questions about the frequency, the amount and the intensity of activity they did in a week. This information was collected in 1991-1993 (the study start), 1997-1999 and 2002-2004 (the study end). The participants were analysed separately depending on whether they followed physical activity guidelines of at least 2.5 hours a week of moderate to vigorous physical activity.
Moderate-intensity exercise is defined as working hard enough to raise your heart rate and break a sweat, such as walking fast or pushing a lawn-mower. Vigorous-intensity exercise is defined as any exercise that causes a person to breathe hard and fast and significantly accelerate their heart rate, such as jogging or riding a bike at speed.
During each of the three time periods, the study participants were also clinically examined, had their height, weight, waist and hip circumference and blood pressure measured, and answered health and demographic questions.
A fasting blood sample was also taken, so the levels of two proteins known to be associated with inflammation – C-reactive protein and interleukin-6 – could be measured.
C-reactive protein Normal concentration in healthy human serum is usually lower than 10 mg/L, slightly increasing with aging. Higher levels are found in late pregnant women, mild inflammation and viral infections (10–40 mg/L), active inflammation, bacterial infection (40–200 mg/L), severe bacterial infections and burns (>200 mg/L).[23]
The researchers examined associations between baseline physical activity and long-term physical activity and inflammatory markers, after adjustment for:
  • age
  • gender
  • smoking
  • employment grade
  • body mass index
  • chronic (long-term) illness

What were the basic results?

The researchers found that approximately half of the study’s participants stuck to the recommended 2.5 hours a week of moderate to vigorous physical activity across all three assessments over the 10 years. Fulfilling the physical activity recommendations was associated with lower levels of inflammatory markers at baseline. There was no significant association between physical activity levels at baseline and change in the levels of inflammatory markers over time. This meant that the difference remained stable.
People who fulfilled the physical activity guidelines at all points during follow-up had lower levels of inflammatory markers than those who only fulfilled the guidelines at one point of follow-up, if at all. In addition, people who reported an increase in physical activity of at least 2.5 hours a week during the study had reduced inflammatory markers compared with those whose activity levels remained stable.
The researchers found that these associations were independent of measures of ‘fatness’ such as BMI or waist circumference. This is important because fatness could be used to explain the association seen, as people who adhered to the physical activity guidelines tended to have lower BMI, and fat tissue is a key site for the production of several inflammatory markers.
The fact that the association remained even in people with higher BMIs or waist circumference suggests that exercise can still benefit people who are overweight or obese with no previous history of exercise. As the Mail’s headline says, “it is never too late” to start exercising.
The researchers also found that people with higher levels of inflammatory markers at baseline had reduced physical activity over the follow-up period. This may be because inflammatory processes are thought to be involved in loss of skeletal muscle and functional decline. 
So, while exercising in middle-age can bring important benefits, to achieve the greatest potential benefit from exercise, people should aim to remain physically active throughout their lives.

How did the researchers interpret the results?

The researchers said: “Regular physical activity is associated with lower markers of inflammation over 10 years of follow-up and thus may be important in preventing the pro-inflammatory state seen with aging”.

Conclusion

This study has found that people who did at least 2.5 hours of moderate to vigorous exercise regularly had lower levels of inflammatory markers over 10 years of follow-up. Levels of inflammatory markers gradually increase with age, and they are thought to play a role in the development of cardiovascular disease and other age-related conditions.
This was a prospective cohort study, which used people from a well understood cohort (the Whitehall II cohort, which recruited participants from the civil service). Participants in the study were followed for a long period, and measurement of all the exposures and outcomes of interest were taken repeatedly. However, although a cohort study was the appropriate study type to investigate the association between exercise and inflammatory markers, it cannot prove that exercise directly caused the differences as other unmeasured factors may have contributed. Also, when interpreting the results it is important to consider that the researchers measured inflammatory markers rather than the incidence of cardiovascular disease. Also, the study collected levels of activity using a questionnaire, which means that levels may not have been reported accurately. Finally, most of the people in the active group were men, so this finding may not apply to women.
However, this study adds weight to the case for regular exercise. The news coverage has focused on the fact that the average age of the participants was almost 50 years old, showing that exercise is beneficial at any age. 
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links To The Headlines

Exercising later in life can ward off heart problems. The Daily Telegraph, August 14 2012

Links To Science