Richard David Feinman

The King in Hamlet says “you cannot speak of reason to the Dane and lose your voice” and most Americans do feel good about the Danes. We hold to the stereotype that they are friendly folk with a dry sense of humor like Victor Borge.  That is why Reuben and Rose Mattus, the Polish-Jewish immigrant ice-cream makers from the Bronx who tried to find an angle that would allow them to compete with Sealtest^® and other big guns, picked Häagen-Dazs^® as the name for their up-scale ice cream, even including a map of Denmark on the early packaging. (Never mind that there is no Scandinavian language that has the odd-ball collection of foreign-looking spelling; Danish does not have an umlaut and I don’t think any Indo-European language has the combination “zs;” there is Zsa Zsa Gabor, of course, but Hungarian is a Uralic language related only to languages that you never heard of).

The original post here held that the Mattuses would have been very surprised to see that products like their high-butterfat ice cream are now a target of the Danish government which instituted a tax on foods containing saturated fat on October 1 of 2011. The tax, I am happy to say has since been repealed.  In a brilliant turn-around that gives a great insight into the mind of the tax man, the Times reported that ” the tax raised $216 million in new revenue. To offset the loss of that money, the Legislature plans a small increase in income taxes and the elimination of some deductions.” Get it? They are going to increase taxes to cover the money that they hoped to have, never mind, that the intention was to stop people from buying the stuff that would bring in the revenue.

The original idea for collecting taxes on a number of items including “sugar, fat and tobacco,” came from  Jakob Axel Nielsen (right), then Sundhedsminister.  A graduate of the law school at Aarhus, Nielsen is reputed to know even more about science than Hizzona’ Michael Bloomberg.  The LA Times points out, however, that “for those who may be tempted to call for Nielsen’s job, please note that he stepped down…last year.”

One of the things that is surprising about all this is that, in  2009, a combined Danish and American research group whose senior author was Dr. Marianne Jakobsen of Copenhagen University Hospital published a paper showing that there was virtually no effect of dietary saturated fatty acids (SFAs) on cardiovascular disease.  The study was a meta-analysis which means a re-evaluation of many previous studies. The authors concluded that the results “suggest that replacing SFA intake with PUFA (polyunsaturated fatty acid) intake rather than MUFA (monounsaturated fatty acids) or carbohydrate intake prevents CHD (coronary heart disease) over a wide range of intakes.”

As in many nutritional papers, it is worthwhile to actually look at the data.  The figure below, from Jakobsen’s paper shows the results from several studies in which the effect of substituting 5 % of energy from SFA with either carbohydrate (CHO) or PUFA or MUFA (not shown here) was measured.  The outcome variable is the hazard ratio for incidence of coronary events (heart attack, sudden death).  You can think of the hazard ratio as similar to an odds ratio which is what it sounds like: the comparative odds of different possible outcomes. The basic idea is that if 10 people in a group of 100 have a heart attack with saturated fat in their diet, the odds = 10 out of 100 or 1/10.  If you now replace 5 % of energy with PUFAs for a different group of 100 and find only 8 people have an event, then the odds for the second group is 8/100 and the odds ratio is 0.8 (8/100 divided by 10/100).  If the odds ratio were 1.0, then there would be no benefit either way, no difference if you keep SFAs or replace.  So in the first figure below, most of the points are to the left of the point 1.0, suggesting that PUFA is better than SFA but the figure on the right suggests that SFA is better than CHO.  But is this real?

You probably noticed that you would have the same odds ratio if the sample sizes were 1000.  In other words, a ratio gives relative values and obscures some information. If there were a large number of people and the real numbers were actually 8 and 10, you wouldn’t put much stock in the hazard ratio; decreasing your chances of a low probability event is not a big deal; you double your chances of winning the lottery by buying two tickets.  In fact, whereas heart disease is a big killer, if you study a thousand people for 5 years there will be only a small number of coronary events. I discussed this in a previous post, but giving Jakobsen the benefit of the doubt that there were really differences on outcomes, we need to know whether the hazard ratios are really reliable.  In this case, Jakobsen showed the variability in the results with “95% confidence intervals,” which are represented by the horizontal bars in the figure.

The 95% confidence interval (95% CI) is a measure of the spread of values around the average. It tells you how reliable the data is. Technically, the term means that if you calculate the size of the interval over and over, 95% of the time the interval will contain the true value. Although not technically precise, you could think of it as meaning that there is a 95% chance of the interval containing the true value.

There is one important point here. It is a statistical rule that if the 95% CI bar crosses the line for hazard ratio = 1.0 then this is taken as indiction that there is no significant difference between the two conditions, in this case, SFAs or a replacement.  Looking at the figure from Jakobsen, we are struck by the fact that, in the list of 15 different studies for two replacements, all but one cross the hazard ratio = 1.0 line; one study found that keeping SFAs in the diet provides a lower risk than replacement with carbohydrate. For all the others it was a wash.  At this point, one has to ask why a combined value was calculated.  How could 15 studies that show nothing add up to a new piece of information. Who says two wrongs, or even 15, can’t make a right?  The remarkable thing is that some of the studies in this meta-analysis are more than 20 years old. How could these have had so little impact?  Why did we keep believing that saturated fat was bad?

Taxing Saturated Fat.

Now the main thing that taxes do is bring in money.   That’s why it is not a good idea to tie it to a health strategy unless you are really sure (as in the case of cigarettes). For one thing, there is something contradictory (or pessimistic) about trying to raise money from a behavior that you want people to stop doing.   In any case, given that during the epidemic of obesity and diabetes, saturated fat intake went down (for men, the absolute amount went down by 14%), and that there was no effect on the incidence of heart disease (although survival was better due to treatment), there is every reason to consider  the possibility of unexpected negative outcomes (think margarine and trans-fat).  Although now repealed, it is worth considering possible unintended consequences (since the sugar tax is still alive).  Suppose that the Danes had reduced consumption of saturated fat but still ate enough to bring in money. And suppose that this had the opposite effect — after all, if you believe the Jakobsen study, substituting carbohydrate for saturated fat will increase cardiovascular risk.  So now there would be a revenue stream that was associated with an increase in cardiovascular disease.  What would they have done?  What would we do? Well, we’d stop it, of course.  Yeah, right.