Posts filed under Medical news (341)

Q:  Isn’t Friday, after the morning rush, a great time to publish a story about benefits of beer?

A:  Yes, the Herald did much better than Medical Daily or Cell Metabolism on that front.

Q: Did the researchers study beer effects in humans, or was it another mouse study?

A: It was a mouse study, but no beer was harmed during the research. The mice were fed nicotinamide riboside directly.

Q: What’s this nicotinawhatsit beer vitamin?

A: It’s related to the real vitamin niacin (B3), and the body can turn it into the same thing, called NADH or NAD+

Q: And?

A: In mice, at least, it’s good for cholesterol and also has effects on some molecules thought to be related to aging.

Q: Wasn’t that supposed to be red wine, not beer?

A: Yes, resveratrol in red wine was also supposed to affect the same molecules.  There has been some controversy about the research, though.

Q: How much beer would you need to drink to get enough nicotinawhatsit?

A: The research paper doesn’t mention beer at all, nor does the video interview linked at Medical Daily.  The researcher just say the compound is found in “milk and some other foods”.

Q: So where does the beer come from?

A: Well, it makes a good story.  And brewer’s yeast, like all organisms, does produce some of the compound, so it could be in beer.  There’s also a patent for using mutant yeast to make it. And there’s no evidence that it isn’t found in beer.

Q:  Have you seen the  new story in Stuff about chocolate being good for your heart?

A: Indeed.  A fine example of the genre.

Q:  What did the researchers find out about the benefits of chocolate this time?

A: Absolutely nothing. (Here’s the research paper)

Q: Then what is the story about?

A: They assumed that there were significant cardiovascular benefits of high-cacao dark chocolate, based on short-term studies of blood pressure and cholesterol, and worked out what the population impact of chocolate therapy would be if that was true.

Q: And is it true?

A: That’s not clear.  If you remember the last time we encountered ‘chocolate for health’, the benefits in that study were pretty marginal. This time the researchers cite a pooled set of studies giving a somewhat larger estimate of the benefits.   Also, the research showing benefits on blood pressure and cholesterol has been from very short-term studies, and extrapolating to the longer-term may well be unreliable.  Still, as Prof Reid points out, no-one is going to do any reliable studies, so extrapolation is what we’ve  got.

Q: What about the calories and fat?

A: Well, the studies that provided the estimates of benefit compared chocolate or cocoa powder to a control that supplied the same calories and fat, so we don’t know.   The researchers (and even the newspaper) admit “The study did not take into account weight gain … ”but that is something you would need to consider,” [Prof Chris Reid]  said.”

Q: Ok, if we stipulate all of that, how big were the benefits?

A: Moderate:  treating 10,000 high-risk people with chocolate would, under the most favorable assumptions, prevent about 15 fatal and 70 non-fatal heart attacks and strokes over a ten-year period.

Q: How do the benefits compare to pills?

A: Well, thiazide diuretics provide 2-3 times the blood pressure effect, and simvastatin provides maybe 10 times the cholesterol reduction. And they cost Pharmac less per month than the chocolate would cost you per day. And we really know the reductions in risk factors translate to fewer heart attacks, strokes, and deaths

Q: But didn’t the researchers say that chocolate therapy would be cost-effective?

A: They said it would be cost-effective at a cost of $42/year.   According to their website, if you wander down to your local Countdown, you can currently get Whitaker’s Dark Ghana at $3.79 for 250g. That would be $550/year for the 100g/day dose in the paper. And that’s a sale price.  It’s only cost-effective if you don’t count the cost of the chocolate.

Q: How about cocoa powder?

A: One of the studies that went into the analysis used 31g/day of cocoa powder (`natural’ not Dutch process). That’s cheaper, but it’s still a lot more than $42/year, and 5 tablespoons/day is a lot of unsweetened cocoa powder.

Q: So, should I eat dark chocolate?

A: If you like it, sure.  If you’re just choking it down for the cardiovascular benefits, probably not.

An interesting report in the Herald yesterday on methamphetamine use.   A forthcoming Health Ministry survey apparently shows a decrease in the proportion who report using P over the past year, from 2.1% in 2007/2008 to 1% now (yes, that will be larger than the margin of error; it’s a big survey).

On the other hand, an ongoing Massey University study that interviews police detainees about drug and alcohol use finds that the street price and availability of P have not really changed.

This evidence of a decrease on the demand side is encouraging for two reasons.  First, it suggests a decrease in the number of people who are dumb enough to want to take methamphetamine, which has to be progress.  Second, it suggests that the pseudoephedrine ban wasn’t responsible, as that should have acted on the supply side by driving up street prices.  Can we have our Sudafed back?

The Herald has a story about curcumin, a component of turmeric (which, as you know, is what makes curry stains hard to get rid of).  Apparently it also has some interesting effects on  a component of the immune system. The story appears in quite a few newspapers around the world, and in Science Daily and Medical Daily, which collect this sort of story.

Often it’s hard to tell how much the stories depend just on the press release or whether someone at one of the specialised sites has actually taken a look at the paper.  It’s not hard in this example, though: the paper hasn’t appeared yet.  There seems to be some slipup at the journal. The university press release and all the sites say the paper came out Friday 25th May, but the Journal of Nutritional Biochemistry hasn’t gotten to Friday yet: at the time of writing this they are still on Thursday 24 May.

The Herald has a headline “Wanna live longer? Look on the bright side”.  The story goes on to say

A study of 243 centenarians revealed that most were cheerful and sociable. The positive personality traits may be genetically based, the researchers believe.

If it’s really genetics that produces the positive personality traits, the advice isn’t going to do much good.  The research paper that produced the story is here, for comparison

The story also says

The study involved Ashkenazi Jews from eastern Europe.

Actually, from the US, though many of them were migrants from central and eastern Europe.  Then

They are good candidates for gene studies because they’re genetically similar to one another.

which is true.  But this wasn’t a gene study, and the relative genetic and environmental homogeneity of the Ashkenazim make them a particularly bad choice for a study that compares Ashkenazi centenarians with the US population of all ages.

In fact, the point of the research paper wasn’t to compare centenarians with others.  The main point of the research paper was really to describe the questionnaire that the researchers are using in their genetic study and compare it to other questionnaires measuring similar psychological traits.  We can see this from the concluding sentence in their abstract:

Findings suggest that the POPS is a psychometrically sound measure of personality in centenarians and capture personality aspects of extraversion, neuroticism, and conscientiousness, as well as dispositional optimism which may contribute to successful aging.  

That is, the researchers assume that these personality aspects will turn out to be important (in the genetic studies) and are looking at how well they are measuring these traits.  That’s all perfectly reasonable, it’s just strange to see how it morphs into the newspaper story.

As you will have heard, excises on smoking are going up.  This will raise money (to the extent that smokers don’t quit) and reduce smoking (to the extent that they do quit).   If you’re interested in the modelling used to estimate the impact on these conflicting goals, the Treasury’s Regulatory Impact Statement is a well-written and detailed explanation.

It’s also interesting to note that Treasury agrees the excise costs are already probably higher than the costs to other people imposed by smoking, and since the smoking excise is probably a regressive tax, the only convincing motivation for smoking excise taxes is to stop people smoking and so improve population health in the long term.

In this light it’s interesting that the Herald’s bogus poll for today is on whether increasing costs will lead to fewer smokers: at the moment, only 11% of responders think it will.  Fortunately, there is strong evidence that the poll respondents are wrong.

The Herald has a story claiming that a set of chemicals that have been proposed as an antibacterial additive for meat actually have large effects on sex-hormone levels.  Usually this would be a story about the need to ban the chemicals immediately, but this time the headline is “‘Viagra effect’ from pomegranate juice”, and they’re in favour of it.

Of course, the ‘Viagra effect’ label is completely bogus (the quote marks suggest that it comes from the researchers’ press release, which would be very dodgy if true).  The researchers claim to have found an increase in testosterone levels in men and women who drank a daily glass of pomegranate juice.  Viagra is involved in blood vessel dilation; it has nothing to do with testosterone, and a previous suggestion that pomegranate juice might really have Viagra-like effects has been tested and rejected.

So, what about the testosterone effects?  Well, what we have is a story based on a press release about a small, unpublished, uncontrolled, open-label study. The most positive one could possibly be about this is “It will be worth waiting for the real publication” or,  perhaps, “I hope it’s not true, because messing with steroid hormones like that is scary”.  It’s reassuring to note that last year the same group said pomegranate juice reduced office stress.  In 2009, they said it reduced blood pressure and cortisol levels.   You will notice that the last link is a press release from a manufacture of pomegranate juice, who sponsored all these studies.  I haven’t linked to actual publications, because according to the PubMed database neither of these results has yet been published either.

There’s a lot of this around: a different pomegranate manufacturer has been sued by the US Federal Trade Commission (in 2010).  The Wall Street Journal wrote

The FTC’s target is not POM’s generally worded, eye-catching ads with lines such as “Cheat Death,” said an agency official. That ad showed a bottle of pomegranate juice with a rope around its neck.

Instead, the government complaint is directed at more specific health claims.In addition to talking about arterial plaque and blood flow, some POM ads describe company-funded clinical trials that, according to the company, show POM juice products can slow the progression of prostate cancer by lowering the level of antigens in the body called PSAs.

The agency’s complaint says that some of POM’s studies did not show heart disease benefits and that the prostate cancer study wasn’t conducted in a standard, scientifically rigorous manner.

The findings about pomegranate juice could be true, but it’s clear that the target isn’t people who actually care whether they are true.

The Herald has a story about premature birth rates across the world, which I will hijack to write about an important NZ scientific contribution, and a revolution in medical statistics.

One of the basic treatments for premature babies, which unfortunately is not available everywhere, is a simple $1 shot of corticosteroids.   This treatment was discovered accidentally by the great NZ medical researcher Graham Liggins.  Liggins was interested in what triggered preterm birth, and hypothesised that steroids were involved.  In experiments on sheep he didn’t find any effect on prematurity, but noticed huge differences in lung development in premature lambs given steroids.   A clinical trial in people found a dramatic reduction in deaths, but no-one really paid attention. After rejection from the Lancet, the trial results were published in another journal in 1972.

Over the following 20 years several additional trials were conducted, most of them too small to show a convincing effect. Finally  all the evidence was put together and obstetricians accepted that corticosteroids had an almost magical effect on lung development in premature babies.  The results of all the trials and the summary of their collective evidence forms the logo of the Cochrane Collaboration, an organisation dedicated to ensuring that randomized trial data doesn’t get lost, but ends up being incorporated in medical knowledge.

This September, the annual meeting of the Cochrane Collaboration is being held in Auckland, so if you see nerdy medical types roaming the streets, be nice to them. They can be useful.

The Herald has a headline “Scientists call for urgency on cancer-phone link”.  The actual content is ok, but the story does give the impression that it’s scientific consensus vs evil cellphone companies, which is not remotely true.  There’s a more balanced story in the Daily Mail (and that’s not a sentence you want to find yourself writing too often).

The facts:  there has been an increase in frontal lobe and temporal lobe brain tumours in the UK over the past decade, though not in total brain tumours.   If you lump together the two regions of the brain with increases and exclude all the ones with  decreases, you get about a 50% increase in rates, which comes to a bit less than one extra case per 100,000 people per year.   For context, that’s a bit less than the estimates of numbers of deaths due to phone use while driving.    There was a Danish study last year that did not find any differences between cell phone users and non-users, or differences in side of the head for users, but that doesn’t quite contradict the British results, for two reasons.  Firstly, there’s quite a bit of uncertainty in both sets of estimates, and they are just about compatible with, say, a 25% increase.  Secondly, the Danish study was mostly of non-malignant tumours, which are the most common ones, and the British statistics are for malignant tumours, so it’s possible the effect could be different, though there’s no known reason that it should be.

The increase could be chance (it’s statistically significant, but still), or an increase in diagnosis, or be due to something else entirely.  Or it could, perhaps, be due to cellphones.  In order to be confident it is cellphones we’d need much better evidence, especially as there isn’t really a convincing story yet of how cellphones could promote tumour growth.

The obvious textbook example of time trends revealing a cancer cause is smoking and lung cancer: smoking took off during World War I and lung cancer rates followed. Except that really isn’t the story.  When Richard Doll and Austin Bradford Hill set out to do their pioneering case-control study of lung cancer in London they were both smokers.  They were expecting the increases in lung cancer to be something to do with the dramatic increase in cars and bitumen roads — perhaps car exhaust, or perhaps some of the pollutants that evaporate off as roads are laid.  The real explanation was enough of a surprise that they were planning to extend the study to four additional cities as confirmation before publishing (until confirmation came instead from a parallel US study).   In that case the relative risk was 20 rather than 1.5, and the absolute lifetime risk increase was about 15% rather than about 0.05%, so it was a lot easier (and much more important) to find the real cause.

The Herald has a very good story about a breast-cancer genomics project, where researchers looked at mutations in 2000 stored breast-cancer tumour samples, and used these to pigeonhole the tumours into 10 groups.  The hope is that this information can be used, eventually, to work out which tumours respond to which treatments, resulting in more effective treatment with fewer side-effects.

The researchers are properly careful about the implications

“I want to be very cautious here. This is a very important first step, and now what follows is to validate its clinical use,” Caldas said.