The saturated fat saga continues

OLYMPUS DIGITAL CAMERAWhen it comes to saturated fat and health, nutrition advocates are divided into two distinct camps:

  1. Saturated fat is evil incarnate and causes all kinds of trouble
  2. Saturated fat is actually healthy and we should stop worrying about it

A recent study (actually a study of studies, or a meta analysis) did absolutely nothing to change anyone’s mind.  If you remain confused about this issue, you’re not alone.  I am, too.

The study in question combined results from dozens of studies to tease out the relationship between dietary fats and the risk for heart disease.   The number of subjects was over 600,000.  That’s a lot of data.  What did it show?

When looking at intake of dietary fats, the relative risk for heart disease (1.00 representing neutral risk) was

  • 1.16 for trans fats
  • 1.03 for saturated fat
  • 1.00 for monounsaturated fat
  • 0.98 for unsaturated omega-6 fats
  • 0.87 for omega-3 fats

In other words, trans fats increase risk, omega-3 fats seem to lessen risk, and there isn’t that much difference between saturated, omega-6 and monounsaturated fats.

Here’s the results when looking at fatty acid levels in the blood:

  • 1.05 trans fats
  • 1.06 saturated fats
  • 1.06 monounsaturated fats
  • 0.94 unsaturated omega-6 fats
  • 0.84 omega-3 fats

Again, omega-3 fats have the lower risk profile, while there isn’t that much difference between the other types of fatty acids.

The researchers conclude that there isn’t much solid evidence to recommend a diet that’s high in omega-6 unsaturated fats and low in saturated fat.

The problem with this study, and frankly with most other diet studies, is that it relies on people giving truthful and accurate information about what they eat.  And unfortunately, that’s never guaranteed.  If someone called you up and asked you what you ate yesterday, or last week, or during the past year, would you be able to give an accurate account?  Would you want to?  Do you really want to admit to the health investigator that you ate a pint of Ben ‘n Jerry’s ice cream for dinner, or that you never touch vegetables, or you eat pepperoni pizza 4 times a week?

Measuring actual blood levels of fatty acids gives a more accurate picture of a person’s status, and as you can see, even those results didn’t give much of edge to unsaturated omega-3 vegetable fats.  Nevertheless, plenty of other nutrition experts reacted negatively to this meta-analysis, even demanding that the study authors retract their findings.  The critics claim the data undermines the message of healthy diet.  Well, their definition of healthy diet.  They’re sticking to the anti-saturated fat dogma.

Then there’s the decidedly pro-saturated fat crowd.  Predictably, these voices come from people with vested interests in saturated fat foods: the palm and tropical oils and dairy industries.  They claim saturated fats raise HDL (good cholesterol) and that dairy fats have unique health properties.   No surprise, the vegetable oil industry sponsors its own nutrition-expert-mouthpieces to promote the benefits of unsaturated fat.  As always, you can’t go wrong if you Follow The Money.  Unfortunately, nutrition research isn’t immune from this effect.

Let’s add to the confusion: a recent article in the Wall Street Journal examined “Why Runners Can’t Eat Whatever They Want” (subscription required).  It turns out, highly trained, thin, muscular marathon runners with low cholesterol still end up with coronary heart disease.  Why?  Doesn’t low cholesterol and low body weight guarantee perfect health?  Apparently not.  Some studies show that marathoners have more arterial plaque than sedentary people.  As the WSJ article noted, a lot of marathon runners assume they can eat whatever they want, since they’re burning a lot of calories.  Some admit to indulging in high fat/high sugar treats.

Keep in mind, heart disease has plenty of other contributing factors, some of which haven’t been clarified yet.  As Dr. David Katz of Yale University points out, it’s impossible to just change one thing about your diet without impacting lots of other things.  He correctly points out that:

Our one-nutrient-at-a-time approach to diet and health has been a decades long public health boondoggle. Our penchant to talk about nutrients rather than food is antiquated and substantially misguided.

What should you do?  Stop worrying about eating more or less of one particular fatty acid, and think about your whole diet.  The best plan is a plant-based Mediterranean-style diet, which is linked to plenty of health benefits, as well as easier weight control.  And maybe go easy on the marathon running.

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