by Marion Nestle
Nov 7 2007

Trans Fat Dilemmas

I have long talked about trans fat as a calorie distracter. People think “trans fat-free” means “calorie-free” when it most definitely does not. Whatever replaces trans fats will have just as many calories–130 per tablespoon, meaning that each tablespoon is 5% of a day’s average calorie intake. That’s why I either laugh or cry when I see “zero grams trans fat”
on the labels of junk foods. Trans fats raise the risk of heart disease a bit more than do the saturated fats that occur naturally in foods. But trans fats are unnatural and unnecessary and it’s good to get rid of them. Yesterday’s Wall Street Journal explains how food companies are struggling to find replacements that do not increase the amount of saturated fat in processed foods. This, as it turns out, is not so easy to do. I discuss all this in the fats-and-oils chapter of What to Eat, so I’m happy to see the WSJ take it on.

  • Ok, except that naturally occuring saturated fat does not cause heart disease.

  • Hi Anna–I wish it were that easy, but that’s not what the science really says. It is true that no nutrient ever causes heart disease by itself but saturated fat, no matter where it comes from, contributes to raising blood cholesterol levels, and high cholesterol levels contribute to raising the risk for heart disease. What makes these relationships seem confusing is that this is a multi-step process, and not everyone reacts the same way to dietary and other risk factors. But plenty of evidence suggests that animal fats–which are, after all, naturally occurring–raise blood cholesterol levels. These are the same studies that show that trans fats raise blood cholesterol levels. And most people eat more saturated fat than they do trans fat. So saturated fat remains a concern. Thanks for writing, as always!

  • Anton

    Interesting, Marion. But I’m puzzled by the amount of evidence to the contrary regarding saturated fat.

    Ronald Krauss’s work clearly suggests that level the LDL itself is a poor predictor of heart disease. The size and density of the LDL particle is far more critical.

    Heart disease patients, for example, are three times more likely to show a predominance of small, dense LDL, instead of the larger, less dense variant of LDL. The larger, less dense LDL is far less atherogenic.

    Paradoxically, the more saturated fat in the diet, the larger, and less dense the LDL. Saturated fat actually appears to favor the less atherogenic form of LDL. This has been demonstrated and duplicated in a number of studies. High-sugar, high-starch diets (and diabetes) tend to produce high concentrations of the small, dense LDL, as seen in heart disease patients.

    Saturated fat, in addition, tends to raise HDL levels.

    What’s more, in Westman’s and Volek’s work, diets containing 2 to 3 times the ‘recommended’ limit of saturated fat raised LDL only slightly, if at all, provided of course, the background diet contained little carbohydrate.

    As I recall, the Framingham data, as well, showed no correlation between heart disease and saturated fat in the diet.

  • Marion, have you ever *seriously* looked into the saturated fat-cholesterol “proof” from a skeptical standpoint (like a scientist, who not only must prove a hypothesis, but must try to disprove it too?)? Not only won’t you find a smoking gun, you won’t even find the smoke or the gun. A half century+ and billions of dollars later (resources that could have been put to much better use!), the case against saturated fat not only hasn’t been proven, it has so many holes punched into it that it looks more like air than even Swiss cheese. Poorly designed studies; badly analyzed data; and political, social, and economic forces have propped up this poor excuse for a theory for far too long, with disasterous health consquences for not only the US, but now the rest of the world (arriving late to the low fat party).

    Anton outlined just a bit of the important contrary evidence, but there is even more ( is a good place to start). Uffe Ravonskov and Malcolm Kendrick also have great books that dissect what is really shown in the scientific studies about sat fat’s role (or lack thereof) in CVD (Kendrick’s book is an easy, quick read). For several decades now, the scientific evidence in CVD research has been leading farther and farther away from saturated fat (homcysteine, inflammation, hyperinsulinemia, hyperglycemia, and on and on). But it seems the diet dictocrats are stubbornly clinging to this raft of saturated fat, so afraid to let go, when the Coast Guard is waiting patiently in plain sight to rescue them.

    It’s past time to say it like it is: saturated fat has no clothes.

  • Jane

    And, let’s just step back and look at saturated fat from a ‘common sense’ point of view.

    I don’t need studies to tell me that eating natural animal fat is perfectly good for the human body. Evolution explains it clearly enough for me.

    That said, I would prefer to eat the saturated fat from grass-fed, free roaming healthy animals than feed-lot products, for both health and ethical reasons.

  • I partially agree with Jane’s comment when it comes to evolution, but the reality is, when humans evolved to be omnivorous, the animals they ate were WILD and studies have shown that they were much leaner and contained more monounsaturated fats. Even though grass-fed, free roaming animals are a healthier choice, I highly doubt their fat composition is still the same because of domestication.

    In terms of the saturated fat research, I’m interested to see how many studies there are showing a link between sat fats and cholesterol for every study that doesn’t show one. As much as we try to be accurate with our science, it certainly is not, especially in the field of nutrition where individual response plays a role. It takes a LOT of studies for scientists to finally agree on something, and it can’t be disproved by just a handful.

  • Anton

    I’d also wonder this: if saturated fats are so deadly, why does the body create reserve fuel stores that are 30% to 40% saturated fat? The fuel that our ancestors relied on between meals, or on those occasional lean hunting days, was triglyerides from body fat, which are about 35% saturated fat. Not all that different from today’s domestic pork.

    In fact, the fat your body creates from food — even from wholesome whole grains — is predominantly palmitic acid. A saturated fat.

  • I enjoyed the comments today while I ate my three pastured eggs, over easy, cooked in a liberal amount of grass-fed raw butter. Sometimes I even throw away an egg white (the boring part) and add an extra yolk (the best part!).

    Vincci, I highly suggest reading at least one of the books that I mentioned in my earlier comment, or the latest book from Taubes. It’s always good to look at important issues from more than one angle. You may begin to see why a LOT of scientists agreed on something that was not on very sound scientific ground. And as my husband (a research scientist, though not in nutrition) always says, “something is wrong when all the scientists agree”.

  • Jane

    Vincci, you have a good point about animal fat composition of wild vs. domestic. I never thought about that.

    Anna, you’re making me hungry!

  • Look up “rabbit starvation” if you think a steady diet of only lean wild animal protein (boneless, skinless chicken or turkey breasts?) is a good thing. The Native American’s figured it out ages ago.

    And consider that the current practice among most meat eaters is to primarily eat the skeletal muscle meats, the leanest cuts at that; the rest is now so unprofitable (but not inedible) that one cannot even find many cuts, organs, and bone parts at most butcher counters anymore – it goes directly from the processor to the “mystery meat” industry (hot dogs, spam, etc.) and the pet food industry (that’s the best part of the commercial pet food, though, the rest is primarily garbage).

    But our ancient ancestors went for the fattiest and most nutrient dense parts first — the organs, the heart, the brains, & other luscious tidbits (!), then the lean muscle meat.

  • Question about acrylamide:

    I heard on the radio today that a study has demonstrated that the cooking of potatoes in oil, whether on top or in the oven, raises acrylamide to dangerous levels.

    In my novice readings, I have learned that traditional, more saturated fats may be more stable than the industrial veggie oils.

    So, to what extent are these results impacted by the frying fat?

  • Pingback: What to Eat » Bad news about acrylamide()

  • Jill Princehouse

    Good research has shown we need 7-10% fat in our diet. We can obtain that amount of fat in a plant-based diet-no dairy, no meat, and no added fats. Plants contain all the fat we need. We should not add any fat. In “What to Eat” it’s stated we need 2 tablespoons of fat daily. That implies we need to add it-like olive oil to our salad dressing. If we add any fats/oils to a plant-based diet, we have more than 10% fat, which is unhealthy.