It's in your scenes, not your genes

The Big Health Story of last week was the Mediterranean diet is good for you story, that we blogged about at the time.  Of course, it didn't take but a couple of days before the Epidemiology Establishment--facing NIH funding cuts--decided to proclaim the need for 'more research' to see what it is in almonds or wine or olive oil that does the miracles, er, the modest reductions in heart disease--Gina Kolata broke the Big Story in the NYT, and also the follow-up.

Of course, in basic terms we've known for years or even decades that the Mediterranean diet has benefits.  The basic dietery differences between lower and higher risk components and habits are clear, even if the details down to how many ounces of McFood you can eat per year per tenth of a percent reduction in some disease risks (in some people) are not known.  The main findings were dramatically demonstrated years ago in a study in Finland, and in many others, as back issues of the NY Times will show, and components have been incorporated into a host of popular diets, and even the US government's dietary recommendations.  So, the story isn't really new, no matter how loudly it's been tooted now.

And, the new study didn't add anything at all new to the methodological toolkit of nutritional studies or epidemiological studies in general, and studies of diet and nutrition are notoriously unreliable.  Even this supposed ground-breaker did a poor job with its control group, and it's perfectly possible that the reason the experimental groups, who added nuts or olive oil to their diets, were as compliant with the diet as they were was because they were given weekly allotments.  So, how that could be translated to the general public changing their diets long-term is hard to figure, as implementing health education is a difficult task.  So why all this new research won't just be more of the same, giving us conflicting, hard-to-interpret results that are hard to talk people into anyway (well, maybe the daily glass of red wine wouldn't be so hard) is not clear.

What is afoot, rather than a massive effort to help Americans alter their diets and gain better health, is of course lobbying for 'more research'.  If you are naive (very naive) you may not realize that what every epidemiologist from here to Timbuktu will propose will be very large, very long, very comprehensive follow-up studies to determine the tenths-of-percent effects of dietary components that we absolutely need to document (and, it is not just cynical to say so, to keep each of their labs running handsomely for many years as a not-so-incidental by-product).

The nature of all of this, from the New England Journal's hoopla release of the study, to the modest findings and questionable data of the study itself, to the amnesia over the long-standing knowledge of the same basic findings, all shows the irresponsibility of so much that is wrong with NIH (and its reciprocal copy-cats in the EU science establishments).

Again, the study's findings seem almost patently plausible given what we know.  There is nothing serious to be gained by pouring huge amounts of money to fine-tune the results.  The complexity of lifestyle risk effects and their great difficulty in being accurately ascertained, are huge relative to the bottom line we already basically know.  The funds that schools of public health will suck up, relative to what smaller, but seriously focused studies, could do for countless junior, perhaps more deeply thinking investigators, nor what real changes in health-habits could do to make enormous reductions in disease and medical care burdens in western countries are a symptom of the sickness of our health establishment.  How to convince people to change their health habits--health education--is still a fundamental question; perhaps they money that's going to be sunk into figuring out just how many almonds and tablespoons of olive oil we should be eating everyday, should be diverted to figuring out how to do effective health education instead.

Environment vs genetics
It is slightly refreshing, we must admit, to see a study that doesn't slyly say we need to look for genetic susceptibility to the bad effects of not eating almonds or olive oil.  Clearly most instances of the diseases that are being GWASed and subject to other similar types of study are not in our genes but in our scenes--how we live and what we eat.

Of course, the gold standard in science is the ability to use what one thinks one understands to make predictions.  Predictions borne out tend to confirm one's understanding.  Anybody want to take bets as to how long it is before the geneticists, seeing the threat of lots of funding shifting to these epidemiological boondoggles, jump in, asserting that the key is to do the genetics of response or risk related to these diets?

We rant regularly on this here, because there is so much waste, and minor incremental research at high cost (and this, a time of budgetary restriction and lack of science jobs), that somebody needs to at least point it out again and again.  We don't have a horse in this race, and nothing to lose or gain by expressing our views.  The likelihood of change is very small, but the need for it is great.

Mediterranean diet cuts risk of heart disease!

This story is making headline news yet again, including at the New York Times, where Gina Kolata describes a new study done in Spain of the effects of adding extra virgin olive oil or nuts, fish, fruits, legumes and red wine to the diet, and reducing the consumption of red meat and processed baked goods.  (Note that the pyramid below was adapted from Consumer Reports Nov 1994.)

From www.womensheart.org

The total study group of about 7000 men (aged 55-80) and women (aged 60-80) was divided into 3 subgroups, and asked to follow the Mediterranean diet (MD) with extra virgin olive oil, the MD with nuts, or a low-fat diet.  They weren't asked to lose weight or to exercise.  The MD groups were given olive oil or nuts every week, and counseling as to how to follow the diet, while the low-fat diet group (the control group) was given a pamphlet on how to follow the diet when enrolled in the study, and then annually until 2006, when it was recognized that their adherence to the diet was poor, at which point researchers added further intervention. This group still never could consistently follow the low-fat diet, and instead were essentially eating their usual diet. 

Recruits were people without heart disease but with type 2 diabetes, or at least three major risk factors ("smoking, hypertension, elevated low-density lipoprotein cholesterol levels, low high-density lipoprotein cholesterol levels, overweight or obesity, or a family history of premature coronary heart disease").  They were followed up until either they dropped out or until the year 2010. The total person-years in the study was about 12,000, 11,000 and 10,000, by group. 

The paper is published in the New England Journal of Medicine.  The researchers assessed primary and secondary outcomes, with the former being heart attack, stroke or death from cardiovascular disease, and the latter being heart attack, stroke, death from cardiovascular disease or death from any other cause. 

The median follow-up period was 4.8 years. A total of 288 primary-outcome events occurred: 96 in the group assigned to a Mediterranean diet with extra-virgin olive oil (3.8%), 83 in the group assigned to a Mediterranean diet with nuts (3.4%), and 109 in the control group (4.4%). Taking into account the small differences in the accrual of person-years among the three groups, the respective rates of the primary end point were 8.1, 8.0, and 11.2 per 1000 person-years.  Outcomes According to Study Group.). The unadjusted hazard ratios were 0.70 (95% confidence interval [CI], 0.53 to 0.91) for a Mediterranean diet with extra-virgin olive oil and 0.70 (95% CI, 0.53 to 0.94) for a Mediterranean diet with nuts.

And,

In this trial, an energy-unrestricted Mediterranean diet supplemented with either extra-virgin olive oil or nuts resulted in an absolute risk reduction of approximately 3 major cardiovascular events per 1000 person-years, for a relative risk reduction of approximately 30%, among high-risk persons who were initially free of cardiovascular disease.

There was no effect of diet on mortality from all causes.  That is, the difference in total number of deaths between groups was not statistically significant.  The effect of diet on cardiovascular disease was apparently through stroke, not heart attack.  People following the Mediterranean diet did not lose weight, nor reduce the amount of fat in their diet, so the effect, the researchers say, was of dietary components alone. 

Interestingly, when researchers compared the merged MD groups with controls recruited before and after 2006, they found that "adjusted hazard ratios were 0.77 (95% CI, 0.59 to 1.00) for participants recruited before October 2006 and 0.49 (95% CI, 0.26 to 0.92) for those recruited thereafter (P=0.21 for interaction)."  Remember that the researchers decided to do more intervention with the control group after 2006. 

But how is that to be interpreted?  Were controls adhering better to the low-fat diet after 2006, and it turns out to be significantly worse than the MD?  Or vice versa?  Did the act of intervention itself made a difference somehow, or were the people recruited after 2006 metabolically different, older, sicker or something else from those recruited before?  Whatever the reason for the difference, it does suggest that comparison between the three groups is not a simple comparison of three different diets.

If this study is as significant as the write-ups are saying, it means that the effect of changing diet can be significant enough to be detectable within a relatively short time span (this study spanned 2003-2010, with subjects apparently included for varying lengths of time).  This suggests that the effect of a non Mediterranean diet over a lifetime is reversible, and thus that risk isn't as genetic as some think (not a surprise!), risk factors like blocked arteries may be reversible by diet, cholesterol can be changed by diet (this is also well-known), being overweight is not a significant risk factor (results on this issue go back and forth), and low-fat diets aren't protective (this, too, has been shown before, though doesn't seem to have caught on with the public). 

And, while this study does confirm things that have already been known, actually rather well and for quite a long time, it also means that people on the Mediterranean diet still die of cardiovascular disease, particularly heart attacks.  Rather than 11 CVD deaths per 1000 person-years, there were 8.  So, the difference may be statistically significant, but it's not qualitatively huge, like 25 vs 2, or even 11 vs 2.  Though, of course if you're one of those three, that's an incalculable difference.  Further, we don't know whether it's eliminating red meat and baked goods rather than adding olive oil and wine and nuts that makes the difference.

One can ask to what extent we should even be doing more and more studies of the same basic idea, once we have systematic data in its favor (dramatic disease benefits were found in a major North Karelia Finland project a long time ago, for example, in a huge dietary intervention study in a place that had, at the time, the highest CVD rates in the world).  There are various ways to measure effects and benefits, and to define outcomes, and these are relevant to evaluating any studies of diet and health.

If nothing else, this study is a reminder that if you reduce deaths from one cause, deaths from other causes go up.  People do still die of something.