It's not your genes, stupid.

Imagine traveling back in time and meeting your caveman ancestor of 10,000 years ago. Imagine telling him about what life is like today: that, with the tap of a finger you turn darkness into light, a cold room into a warm one and a tube in the wall of your cave into a spring of hot and cold water. You tell him...

you can fly from one place to another, and watch any place on this Earth without ever leaving your cave. You tell him you never have to run after your food, or fear that you run out of it. Your ancestor will have a hard time believing you. In his world only his gods can do all that.

Then you tell him how some of your friends think his way of life is preferable for health, which is why you are visiting him because you want to see for yourself. Before I get to your ancestor's most likely answer, let's get on the same page with those friends of ours first.

You have probably heard them talk about the past 10,000 years having done nothing to our genetic make-up. In other words, your ancestor's DNA blueprint was the same as yours. Today this blueprint collides  with a space age environment in which we don't expend any energy to get our food, and the food we acquire delivers far more energy and far less nutrients than what had been the case during 99.9% of human evolution. 

According to this view, today's epidemics of obesity, diabetes, cardiovascular diseases and cancer are simply the collateral damage of this collision. This explanation is so persuasive that it is being parroted by every media type and talking head who can spell the word  'genetics'. I'm afraid it is not that simple. Here is why:

Remember when the 3 billion letters, or base-pairs, of the human genome had first been decoded at the beginning of this century. This decryption had been delivered with the promise of revolutionizing medicine. Aside from new therapies, the hottest items were prognostic and diagnostic tools, which, we were made to believe, would lay in front of each individual his biomedical future. And with this ability to predict would come the ability to prevent, specifically all those diseases which result from an unfavorable interaction between genes and environment.

Almost ten years later we are nowhere near this goal. OK, we have identified some associations between some genetic variants and the propensity to become obese or get a heart attack or diabetes. But these associations are far from strong and they hardly help us to improve risk prediction. Just this year, Vaarhorst and colleagues had investigated the ability of a genetic risk score to improve the risk prediction of conventional risk scores which are based on biomarkers, such as the ones used in the Framingham score. Less than 3% of the study participants would have been reclassified based on the genetic risk score [1].

In a study which was released just yesterday, genetic markers for the development of diabetes in asymptomatic people at high risk, did not improve conventional biomarker risk scoring at all [2]. 

Obviously we are not simply our genes. This is because genes do not make us sick or healthy. Genes make proteins. And on the way from gene to protein a lot of things happen on which genes do not have any influence. To express a gene, as biologists call it, that gene must first be transcribed on RNA and then translated from RNA into the final protein. Whether a gene is transcribed in the first place depends on whether it is being made accessible for this transcription process. Today we know at least two processes which can "silence" the expression of a gene, even though it is present in your DNA. These processes are called DNA methylation and histone modification. Simply imagine them as Mother Nature's way of keeping a gene under wraps.

That's a good thing if the protein product of the silenced gene would be detrimental to your health. It could well be the other way round, too. Anyway, these happenings have been called epigenetics. Epigenetic mechanisms enable cells to quickly match their protein production with changing environmental conditions. No need to wait for modifications of the genetic blueprint which takes many generations and a fair element of chance to materialize. The most astonishing discovery is that these epigenetic changes may become heritable, too. Which means, there is really no need to change the genetic code. 

I believe you get the picture now. While it is true that your ancestor's genetic code is indistinguishable from yours 10,000 years later, the way your body expresses this code in the form of proteins and hormones can differ in many ways. Which is why researchers are now as much excited about epigenetics as they used to be about genetics 10 years ago.

I don't want to be the party pooper, but whenever I see such excitement I'm reminded of how it has often evaporated after some further discoveries. Here I'm skeptical because of the picture, which we are beginning to see. Insulin, for example, is known to regulate the expression of many genes. At least in rats it has been shown that insulin's suppressive effect on gene expression in the liver, can be altered by short term fasting [3]. That means, relatively minor behavioral changes may affect the way our organism expresses its genetic code.   

Observations like these support the idea that we are not our genes, but what we make of them. In plain words: let's not hide behind the "it's-our-stone-age-genes" excuse, to explain why we are fat and lazy and ultimately chronically sick.

Now, back to your ancestor and his response to your friends' suggestions that his way of life is preferable for health. When you also tell him you live a lot longer than the 40 years he has on average, he'll tell you: You have got some nutcase friends over there. Let me live like a god first and then I'll worry about health later.

Maybe, we are not so different from our stone age ancestors after all. 

1.           Lu, Y., et al., Exploring genetic determinants of plasma total cholesterol levels and their predictive value in a longitudinal study. Atherosclerosis, 2010. 213(1): p. 200-205.

2.           Schmid, R., et al., Current Genetic Data Do Not Improve the Prediction of Type 2 Diabetes Mellitus: The CoLaus Study.Journal of Clinical Endocrinology and Metabolism, 2012.

3.           Zhang, Y., et al., Insulin-Regulated Srebp-1c and Pck1 mRNA Expression in Primary Hepatocytes from Zucker Fatty but Not Lean Rats Is Affected by Feeding Conditions. PLoS ONE, 2011. 6(6): p. e21342.

Lu, Y., Feskens, E., Boer, J., Imholz, S., Verschuren, W., Wijmenga, C., Vaarhorst, A., Slagboom, E., Müller, M., & Dollé, M. (2010). Exploring genetic determinants of plasma total cholesterol levels and their predictive value in a longitudinal study Atherosclerosis, 213 (1), 200-205 DOI: 10.1016/j.atherosclerosis.2010.08.053 

Zhang Y, Chen W, Li R, Li Y, Ge Y, & Chen G (2011). Insulin-regulated Srebp-1c and Pck1 mRNA expression in primary hepatocytes from zucker fatty but not lean rats is affected by feeding conditions. PloS one, 6 (6) PMID: 21731709

Screw Your Health?!

So, what's your excuse for not exercising enough, for smoking, for not watching your diet, for getting fatter every year, and therefore having high blood pressure, and too much glucose and cholesterol in your blood?

 That's what the American Heart Association has been telling you for so many years NOT to do. How can I be sure that you, dear reader, are one of those people who only pay lip service to health? I can't, but as a numbers guy I go with the statistics. 

And when health is concerned the statistics tell me that there are obviously only two types of people. Those who do enough for their health, and those who merely think they do. The latter make up 98.8% of the population [1]. That is, only one in a hundred meets all 7 health metrics: not smoking, eating a healthy diet, no overweight, sufficiently physically active, normal blood pressure, normal levels of glucose and cholesterol. Four out of every 5 Americans meet 4 or less of those metrics. Actually, only one in four meets 4 metrics. How can that be when having at least 6 of those metrics will cut your risk of dying from cardiovascular disease by 75% compared to those who meet one criterion or none? How much more incentive do you want?

That's the frustrating question I'm asking myself every day. Because whether it is in the US, in Germany or anywhere else in this world, maintaining health and preventing disease is a frustrating service to provide. I used to think this is so, because when you don't feel it, it is health. And what you don't feel, you don't appreciate. But if that was true, the first diagnosis of a chronic condition, such as heart disease or diabetes, should surely be a wake-up call. But it isn't. Only 40% of smokers quit when  being told that they have such a chronic disease, and that smoking will make it worse [2]. That's still a lot compared to the behavior change in exercise: Nil, no change at all.  And for every American who quit smoking in 2011 another American became obese. 

If you have read my earlier blog posts, you'll remember that I'm a strong advocate of recognizing the autonomic neurohormonal mechanisms which certainly drive our eating and exercising behaviors. But we are not exclusively controlled by those. We still have a few brain centers which give us the abilities and skills that make us human: volition, reasoning, intelligence. Of course you can use them to find the most elaborate excuses for your health behaviors, or rather for the lack thereof. But he who is good for making excuses is seldom good for anything else. That's what Benjamin Franklin said. Are you good for something else? Make that something your health. And start today. Here!

1.           Yang, Q., et al., Trends in Cardiovascular Health Metrics and Associations With All-Cause and CVD Mortality Among US Adults. JAMA: The Journal of the American Medical Association, 2012.

2.           Newsom, J.T., et al., Health Behavior Change Following Chronic Illness in Middle and Later Life. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 2011.

Yang, Q., Cogswell, M., Flanders, W., Hong, Y., Zhang, Z., Loustalot, F., Gillespie, C., Merritt, R., & Hu, F. (2012). Trends in Cardiovascular Health Metrics and Associations With All-Cause and CVD Mortality Among US Adults JAMA: The Journal of the American Medical Association, 307 (12), 1273-1283 DOI: 10.1001/jama.2012.339 

 Newsom, J., Huguet, N., McCarthy, M., Ramage-Morin, P., Kaplan, M., Bernier, J., McFarland, B., & Oderkirk, J. (2011). Health Behavior Change Following Chronic Illness in Middle and Later Life The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 67B (3), 279-288 DOI: 10.1093/geronb/gbr103

How to get those vegetarian zealots off your back.

Does red meat kill you? Only in a vegetarian's dream!

Red meat is the favorite enemy of nutritionists nowadays. Their studies and publications are often (ab-)used by those evangelical vegetarian types who would love to impose their no-meat religion on the rest of us. Don't buy it. Now let me show you how you can profess your love for steak AND support it with the data from the same studies which the zealots use for their vegetarian crusades.

Earlier this year Pan et al. published a study titled "Red meat consumption and mortality" [1]. They had pooled the data of two large prospective studies, the Nurses' Health Study and the Health Professionals' Follow-up Study. Collectively these studies had followed 121,000 people, who were free of cardiovascular diseases at baseline, for more than 20 years. Altogether, the participants accumulated close to 3 million person years for observation. During the observation period close to 24,000 deaths occurred of which 6,000 were of cardiovascular causes, that is heart attack, stroke, heart failure.

The researchers discovered that for every increase of 1 serving of unprocessed red meat per day the hazard ratio of dying from any cause was 1.13 and the hazard ratio of dying from a cvd-cause was 1.2. That means for every increase of a serving of red meat per day the chances of dying from any cause and from a cvd-cause increased by 13% and 20% respectively. Those rates were a little higher for processed red meat. To put this into perspective the researchers also calculated that if all participants had eaten less than half a serving of red meat per day (42g/d), 9% of deaths in men and 7.6% of deaths in women could have been prevented. Wonderful. Sounds impressive, but it isn't for one simple reason:

Unreliable data acquisition. Just ask one question: how did the researchers know how much red meat those people ate? This question cuts to the heart of many, if not most, studies on diet-disease associations. Data on food consumption are typically acquired through food frequency questionnaires (FFQ). These FFQs ask you about your consumption of food items over the past days, weeks or even months. And as you can imagine, such recall can be terribly unreliable. So much so, that other researchers wanted to quantify this effect. So they used FFQs and compared the results with objective quantitative measurement of energy intake and protein intake [2]. And lo and behold, they discovered that if relative risks (such as the hazard ratio mentioned above) were calculated from FFQs they overestimate the true diet-disease association very severely. In fact so severe, that a hazard ratio of, say, 2 would in reality be around 1.3.

What does that mean for a hazard ratio which is, as in the study of Pan and colleagues, less than 1.3 to begin with? It means possibly nothing. You certainly can't conclude from these data that red meat kills you. That's what it means.  And mind you, this inaccuracy of FFQs shows up with recall periods of a few weeks. Pan and colleagues had to rely on FFQs which were conducted YEARS apart. In fact,  data acquisition based on FFQs is so flawed, that the question been raised "is it time to abandon the food frequency questionnaire?" [3]. And the authors state: "We should be very circumspect about analyses of current studies that have used FFQs for dietary assessment." That was 7 years ago. We still have those FFQs and you  still have the media telling you  how bad red meat is for you.

And I'm going to have a real nice steak now. How about you?

1.           Pan, A., et al., Red Meat Consumption and Mortality: Results From 2 Prospective Cohort Studies. Archives of Internal Medicine, 2012: p. archinternmed.2011.2287.

2.           Kipnis, V., et al., Structure of dietary measurement error: results of the OPEN biomarker study. American Journal of Epidemiology, 2003. 158(1): p. 14-21; discussion 22-6.

3.           Kristal, A.R., U. Peters, and J.D. Potter, Is it time to abandon the food frequency questionnaire? Cancer Epidemiology, Biomarkers and Prevention, 2005. 14(12): p. 2826-8.