Choose unsaturated fats for heart health

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{***Noah***}

Coming up on Harvard Chan: This Week in Health…

Setting the record straight on dietary fats and heart health.

{***Frank Sacks Soundbite***}

(So when they say that saturated fat does not affect health– they mean, yes, they’re comparing bad against bad. When you’re looking in observational epidemiology, you have to look at what one nutrient or one food is substituted with. I mean what’s the point of talking about, for example, red meat if you can’t compare it to something else. If you’re going to compare it to eggs and ice cream, well, maybe the red meat will come out fairly good.)

In this week’s episode: Why unsaturated fats are your best choice for heart health.

We’ll speak with one of the authors of a new American Heart Association Advisory about the state of the science on dietary fats—and some simple swaps you can make to include more healthy fats in your diet.

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{***Noah***}

Hello and welcome to Harvard Chan: This Week in Health.

It’s Thursday, July 13, 2017. I’m Noah Leavitt. Amie Montemurro is off.

This week we’re talking all about dietary fats—specifically unsaturated vs. saturated fats.

Foods high in saturated fat are things like red meat, butter, or cheese.

Unsaturated fats are broken down into two categories—monounsaturated and polyunsaturated—and are found in vegetable oils, nuts, seeds, and fish.

Coming up in a few minutes you’ll be hearing from Frank Sacks, professor of cardiovascular disease prevention here at the Harvard Chan School, and one of the authors of a new American Heart Association advisory which urges people to swap out saturated fats for unsaturated fats.

The AHA says doing so can lower a person’s heart disease risk as much as cholesterol-lowering statin drugs.

Researchers—including Sacks—analyzed hundreds of studies published since the 1950s—and they say that overwhelming evidence shows that saturated fats should be consumed in limited quantities.

The advisory comes amid conflicting research and media reports about the health effects of saturated fats.

So we asked Sacks to explain the science, why we are seeing these conflicting reports, and what you can do to add more healthy unsaturated fats into your diet.

I started our conversation by asking Sacks why the AHA felt the need to issue this advisory now.

{***Frank Sacks Interview***}

Frank Sacks: Well, the American Heart Association leadership, about two to three years ago, decided that a major reevaluation of the dietary fast that we eat is warranted in terms of relation to heart disease. One reason for the Heart Association’s decision on that is that, for a few years, there have been contrarian articles published either in the medical literature or by writers who have prominently trumpeted results that dietary fat and health had to be revised, that, in fact, it’s not really so pertinent to health what kind of fats or how much fats we eat.

Noah Leavitt: And so I know the panel reviewed decades of scientific evidence. So what does the science show us about the effects of saturated fats versus unsaturated fats?

Frank Sacks: What we found is that, very, very clearly, saturated fat caused atherosclerosis, which is plaque– cholesterol-rich plaque in the arteries of the heart were leading up to the brain and also heart attacks and strokes in comparison to unsaturated fats. And among the unsaturated fats, the polyunsaturated fats were more protective than the monounsaturated fats. So our conclusion was reduce saturated fat and replace it with unsaturated fats, preferably polyunsaturated fats.

Noah Leavitt: And so you touched on this a second ago. But if the scientific evidence on the harmful effects of saturated fat– it’s so overwhelming. So why have there been these studies that have found no links between saturated fats and heart health?

Frank Sacks: Well, there have been a few of these studies. And what the studies used, essentially, obsolete methodology in their meta-analysis. So what meta-analysis does is it combines all available studies and analyzes all the results together. And what some of them reported is that there was no relation between saturated fat and heart disease. But that’s only because people who eat low amounts of saturated fat in our populations eat a lot of junk food carbohydrate, including added sugars, deserts, white bread. And that’s no good. So when they say that saturated fat does not affect health– they mean, yes, they’re comparing bad against bad. Now saturated fat instead as compared to polyunsaturated or monounsaturated fat, there’s most definitely harm in saturated fat. And finally, if saturated fat is compared to good carbohydrate-containing foods like whole grains, then you see an advantage to reducing saturated fat. Now, I think that some of the authors of these papers were just simply unaware of contemporary methodology and nutritional epidemiology, which Walter Willett and his colleagues developed when they recognized that. When you’re looking in observational epidemiology, you have to look at what one nutrient or one food is substituted with. I mean what’s the point of talking about, for example, red meat if you can’t compare it to something else. If you’re going to compare it to eggs and ice cream, well, maybe the red meat will come out fairly good. And that’s actually what happened some years ago in some epidemiological study.

Noah Leavitt: And so, I mean, the wisdom now is that fats are good. You just have to be careful about which fats you’re choosing.

 

Frank Sacks: Yeah. Well, that’s a very important point. I mean dietary fat is good– absolutely– as long as it is unsaturated fat. And if the dietary fat contains saturated fat or is high in saturated fat, it contributes to heart disease.

Noah Leavitt: For people who maybe hear these terms but don’t know, I mean, what are some prominent examples of saturated fat and then unsaturated fat.

Frank Sacks: OK. Well, one way to differentiate saturated from unsaturated is that saturated fat is solid at room temperature. Unsaturated fat is liquid at room temperature. So if you want some examples of solid at room temperature, you can think of butter, lard, beef tallow, pork fat, coconut fat, palm kernel or palm oil is mostly solid. And liquid oils would be corn oil, peanut oil, soybean oil, sunflower, safflower oil, olive oil, of course.

Noah Leavitt: And so you talked about coconut fat and coconut oil. I mean there were a lot of headlines specifically focusing on coconut oil. Why do you think that has become such a kind of a lightning rod food.

Frank Sacks: Well, there’s been tremendous hype about coconut oil purportedly being healthy. And there really is no basis in science for that. And what we know is that coconut oil is mostly saturated fat. It raises LDL cholesterol, which is the cholesterol that directly causes heart disease, just as much as butter does or other high-saturated-fat foods. So there’s nothing really special about saturated-fat-rich coconut oil beyond its saturated fat. Now, there have been speculations that there are some other ingredients in coconut oil that may be protective. But those are not yet, at least, backed up by any credible scientific evidence yet. There are things that we know about coconut oil– the saturated fat content, the increase in LDL cholesterol, which is bad. And then there’s speculation maybe based on a small number of studies in animals or cells or whatnot that need to be followed up that are not established fact that we can use in human clinical practice or guidelines.

Noah Leavitt: So I think when it comes to– and we’ve touched on this. But when it comes to dietary fats, there can be a lot of conflicting information in the media. I mean there’s always headlines– butter is back! Butter is not back. I mean so what would your advice be to consumers, people at home, as they’re attempting to make healthy choices? What things should they keep in mind?

Frank Sacks: Well, I think, first of all, people should look at established health guidelines produced by organizations like the American Heart Association or the National Institutes of Health or, say for diabetes, the American Diabetes Association and use those guides because they are very, very carefully evaluated, written, framed, vetted in several levels of peer review, especially something like the dietary fats advisory. And those are guidelines that people should look at. What they should not do is sort of look at the latest story in the media because the media approaches science and health findings totally inimically to inform consumers in public health. And what I mean is that the model for the media is to trumpet the latest study. And if the latest study is different from conventional knowledge, they will trumpet it even more. Well, that’s not right. I mean there is context. In the media, if they’re going to do a decent job of it, they’re going to study the context and not just listen to the authors of some research result that may not be done well or may be contrarian for a methodological reason. They need to look at the context. They can do it. There are good investigational reporters. And if they use that skill and investigational journalism onto food guidelines and health guidelines, then that would serve the public much better than the current situation.

Noah Leavitt: So if I’m a person who is looking to get more unsaturated fats in my diet, what are some easy ways to start doing that? What are some maybe healthy swaps people can make?

Frank Sacks: Well, for example, I mean I cook with corn oil because it’s very high in polyunsaturated fats. So I use that for sautéing and on salads. I like the taste of extra virgin olive oil. So I have my favorites and I use that for example. People can deep fry. Deep fried foods– they’re fine. There’s nothing wrong with deep fried foods as long as they’re deep fried in healthy unsaturated oil– sunflower, safflower or canola oil, corn oil. They are all just fine for deep frying, and they will add to the healthfulness of what you’re deep frying for example like fish– deep fried fish. Nothing the matter with that– in fact, it’s very good if the oil is unsaturated.

Noah Leavitt: So like donuts are still not healthy. But if you take something healthy and put it in unsaturated oil, it’s not going to make it suddenly worse for you.

Frank Sacks: Well, yeah. I mean, for example, take eggs. If you fry eggs in corn oil, for example, the net healthfulness of the eggs will be enhanced. But if you fry it in butter or bacon grease or something like that, well, you’re going to create a very unhealthful breakfast.

Noah Leavitt: One of the key messages from the advisory was this idea of replacing saturated fat would healthier fats in the diet can lower heart disease risk as much as cholesterol-lowering statin drugs. So how do making these dietary changes fit into an overall heart disease-prevention strategy?

Frank Sacks: What we concluded in this advisory is that the cornerstone for healthy eating is a healthy dietary pattern– a healthy dietary pattern, for example, like the DASH diet, Mediterranean diet, vegetarian diet. Those are healthful dietary patterns. Now, we say within the healthy dietary pattern, the oils should be unsaturated rather than saturated. And food should be chosen so that the fats that they contain in them will be unsaturated, like nuts for example.

{***Noah***}

That was our interview with Frank Sacks about a new American Heart Association advisory on unsaturated fats.

And we know that making healthy choices when it comes to fat can be confusing, so we’ll be putting several resources up on our website, hsph.me/thisweekinhealth.

We’ll have definitions of the kinds of fat, and examples of foods to eat more of—and ones to try and limit.

That’s all for this week’s episode. A reminder that you can subscribe to listen to us on iTunes or Stitcher, or stream episodes at soundcloud.com/harvardpublichealth.