Saturated Fat: Facts vs. Fiction
For decades, saturated fat was considered heart-health enemy #1. But in the last few years, emerging research and media reports have called the conventional wisdom into question, leaving many people wondering what to do. Are butter and red meat OK now? Should you cool it with the skinless chicken breast? Do you switch to (gasp!) whole milk? Here, we clear up some of the common points of confusion about saturated fat.
Why is everyone now saying saturated fat is not so bad after all?
In recent years, a couple of large-scale studies have found that saturated fat consumption doesn’t actually increase heart disease risk. First, a 2010 meta-analysis, which followed 350,000 people for up to 23 years, found no significant association between consumption of saturated fat and increased risk of heart disease. Then, in March, another meta-analysis — with more than 530,000 subjects, including data from 32 studies — concluded that the science does not clearly support current guidelines to restrict saturated fat.
The media naturally jumped on these findings. After the 2014 study there was a rash of stories accompanied by photos of rich foods, with captions like “Steak — it's not so bad for you” and “Giving up fatty meat, cream or butter is unlikely to improve health.”
Yet the research does not actually say anything about particular foods, just that the current expert recommendations (restricting saturated fat to less than 10 percent of calories, or less than 5 to 6 percent according to the stricter American Heart Association guidelines) may need to be revised.
Revising nutrition guidelines can take years, even when the science is airtight. And in this case, it’s not: Both of the studies mentioned above were controversial. The 2010 study was questioned by some scientists for having flawed methodology. And the 2014 study was subsequently found to have several significant errors that may reduce the strength of its findings. The controversy isn’t reason to discount these studies, but it does mean more research is needed before any recommendations are changed.
So for now, the guidelines published by the federal government and major organizations like the American Heart Association remain the same. In light of the new research, some health professionals are already conveying less concern about saturated fat to their patients, while others are holding fast to the existing guidelines. A good middle ground would be to stick to your health care team’s recommendations, and not to add any saturated fat to your diet until more evidence emerges — especially if you have any history or risk of heart disease or obesity (more on that below).
What is the connection between saturated fat and cholesterol? And how does that relate to heart disease?
We’ve long known that saturated fat raises LDL, or “bad” cholesterol, a major risk factor for heart disease. And of course, two other important factors in determining heart risk are HDL (“good”) cholesterol, which lowers risk, and triglycerides, which raise risk. (These three factors are collectively known as blood lipids.) Saturated fat consumption increases levels of all blood lipids, the good with the bad.
People are often told to cut back on saturated fat in an effort to lower LDL and triglyceride levels. But whenever we cut back on one thing in our diet, we increase another — and for many of us that means increasing our intake of carbohydrates.
The best available science indicates that if you substitute carbohydrates — particularly refined ones — for the saturated fat in your diet, you’ll significantly decrease your good cholesterol and increase your triglycerides. In other words, routinely opting for white toast instead of eggs, or pretzels instead of beef jerky, may increase your overall heart disease risk. Not much research has looked specifically at substituting unrefined carbohydrates (e.g., brown rice, whole-grain bread) for saturated fat, but one Danish study indicates that carbs with a lower glycemic index may not be as harmful.
So if it’s a choice between sugar and butter, your heart would be better off with butter. (Margarine is a whole other story: It often contains trans fat, which is the most detrimental of all for blood lipids, so be sure to check labels and avoid anything listing trans fat or partially hydrogenated oils.)
That said, a recent study of 2,817 participants (all of whom were white and middle-aged) found that in people with a genetic predisposition to obesity, there was a positive correlation between saturated fat intake and BMI. So if obesity runs in your family, cutting back on saturated fat may still be a good idea.
Does it matter if the saturated fat is plant-based or animal-based?
Possibly, but at this point there’s not enough evidence to say for sure.
Only three plant-based oils are considered saturated (even though they also contain some unsaturated fats): coconut, palm, and palm kernel oil. Like all saturated fats, these tropical oils raise LDL levels, which is why they’ve been demonized in the past. But like other saturated fats, tropical oils also raise HDL levels, and they also contain some antioxidants not contained by their animal-based counterparts, like vitamin E and beta carotene.
One study of women in the Philippines found that coconut oil intake wasn’t associated with elevated total cholesterol or triglyceride levels, and was associated with significantly higher HDL. But as the researchers noted, “coconut oil intake was biased towards the younger, more educated women and those with smaller BMI […] Similarly, coconut oil intake was higher among women living in households with more assets and in more urban areas.” In other words, the associations found in this study may have had more to do with the subjects’ socioeconomic status or BMI than with the coconut oil itself.
Again, there may still be some validity to these findings, but don’t stock up on coconut oil just yet. (Unless it’s for high-heat cooking — coconut and other tropical oils have a high smoke point and are good substitutes for more heat-sensitive fats like olive oil when searing or stir-frying.)
What’s the bottom line?
If you’re already following the current dietary guidelines and watching your saturated fat, there’s no reason to make any changes yet, especially if you’re at risk for heart disease. If you’re not following the current saturated fat recommendations, there’s no harm in trying — as long as you replace saturated fat with a variety of unsaturated fats and not with carbs or trans fat. At worst, you’ll miss a few years’ worth of cheeseburgers before the guidelines change. At best, you’ll live to enjoy decades’ worth of turkey burgers.
Christy Harrison, MPH, is a nutritionist specializing in chronic disease prevention, weight management and eating disorders. She writes about food and nutrition for various publications and hosts Food Psych, a podcast about the psychology of eating. Find her at christyharrison.com.