by Marion Nestle
Mar 19 2014

Is saturated fat a problem? Food for debate.

What is a poor eater to do?

The latest meta-analysis of the effects of saturated fat on heart disease finds—none.

This study, reported in the Annals of Internal Medicine (doi: 10.7326/M13-1788), examined the results of

  • 32 observational studies involving 530 525 participants
  • 17 observational studies involving 25 721 participants
  • 27 randomized controlled trials involving 103 052 participants

The result?

Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats. 

This meta-analysis follows an editorial in a Mayo Clinic publication (http://dx.doi.org/10.1016/j.mayocp.2013.11.006) by authors who argue that saturated fat is not the problem.  Carbohydrates (e.g., sugars) are the problem.  The authors argue:

  • Effects of saturated fat on blood cholesterol are weak and transient.
  • Meta-analyses have found a lack of an association between heart disease mortality and saturated fat intake.
  • Stroke studies find that patients with stroke had eaten less saturated fat.
  • Long-term studies find that people with the highest dairy consumption have the lowest mortality risk, and also low diabetes and heart disease.
  • Dietary trials find trivial or no benefit at all from decreasing saturated fat and/or increasing intake of polyunsaturated fat.

On this basis, they say that advice to reduce intake of saturated fat is irrational.

The New York Times asked several experts for comment on the meta-analysis, among them Dr. Frank Hu of Harvard:

The single macronutrient approach is outdated…I think future dietary guidelines will put more and more emphasis on real food rather than giving an absolute upper limit or cutoff point for certain macronutrients…people should try to eat foods that are typical of the Mediterranean diet, like nuts, fish, avocado, high-fiber grains and olive oil.

Dr. Hu was referring to a large clinical trial (not included in the meta-analysis), which concluded that a diet with more nuts and extra virgin olive oil reduced heart attacks and strokes when compared with a lower fat diet with more starches.

The Times story contained a reminder that the American Heart Association issued dietary guidelines last year to “restrict saturated fat to as little as 5 percent of their daily calories, or roughly two tablespoons of butter or two ounces of Cheddar cheese for the typical person eating about 2,000 calories a day.”

How to make sense of this?

I vote with Frank Hu that dietary advice should focus on food, not nutrients.

Focusing on one or another nutrient—fat, saturated fat, cholesterol, or sugar—takes foods out of their caloric as well as dietary context.

My guess: If you balance food intake with physical activity and are not overeating, the specific proportion of fat, carbohydrate, and protein won’t matter nearly as much.

While the arguments about fat v. sugar go on and on:  Eat your veggies, vary the foods you eat, don’t gorge, and enjoy what you eat.

  • pawpaw

    Multiple folks familiar with the history of this field have pointed out that selective data use to fit the sat fat-disease hypothesis, by Ancel Keys in the late 50s, started an inaccurate informational cascade. One still embraced by many today. If all data avail then had been used, the sat fat–heart disease link would have been weak, if at all, the hypothesis would have been revised. Research and analysis published early 60s, and since, have been available to counter Keys’ flawed conclusions.

    See articles such as “Diet and Fat: A Severe Case of Mistaken Consensus” by John Tierney, NYT, or “End the War on Fat: It Could Be Making Us Sicker”, but Melissa Moyer at Slate. For recounting of this history, and missed opportunities to right it. In a balanced diet, processed carbs are not a healthy replacement for most fats, but that’s the path most US eaters have wandered down.

    For inclusion of the latest research you refer to, both as an article or Q&A Podcast, by James DiNicolantonio, a cardiometabolic researcher: http://openheart.bmj.com/. Click on link at upper right.

    Science tends toward self-correction; unfortunately the wrong paradigm on this issue has held sway the last 50 years, though dissenting researchers and their work has always been available to those willing to consider it. Also the eaters who, in honoring their foodways, refused abandonment of traditional, varied whole-food diets.

  • Erik Arnesen

    I really recommend dr. David Katz’ comments on this metaanalysis here: http://www.linkedin.com/today/post/article/20140318132400-23027997-the-new-dietary-fat-study-what-you-ll-hear-and-what-it-really-means.

    Anyway, this study ignores all the clinical trials on fat modified diets that shows that replacing saturated with unsaturated fats decrease cardiovascular risk in the long term (see for instance the Cochrane-metaanalysis by Hooper et al. from 2012). I believe they should weight more than the observational studies, even though the clincal trials aren’t perfect either (adherence is a big problem). Anyway, the replacement nutrients (and foods!) are possibly more important than the saturated fat per se.

    Walter Willett, Frank Sacks & Meir Stampfer just published this comment on annals.org:

    «The meta-analysis of dietary fatty acids and risk of coronary heart disease by Chowdhury et al. (1) contains multiple errors and omissions, and the conclusions are seriously misleading, particularly the lack of association with N-6 polyunsaturated fat.» (http://annals.org/article.aspx?articleID=1846638#tab9)

    To pawpaw: The Seven Countries-studies has been historically important, but today’s dietary recommendations are not based on them. For instance, the recently published Nordic Nutrient Recommendations (http://www.norden.org/no/publikationer/publikasjoner/2014-002) don’t cite Keys at all.

  • David_Brown

    Dissenting researchers generally get ignored because too much emphasis is placed on consensus of opinion. Case in point is Fred Kummerow who says that an excess of polyunsaturated vegetable oils like soybean, corn and sunflower “- exactly the types of fats Americans have been urged to consume for the past several decades – “are responsible for hardening of the arteries. http://www.nytimes.com/2013/12/17/health/a-lifelong-fight-against-trans-fat.html

    The Lyon Diet Heart Study (https://circ.ahajournals.org/content/103/13/1823.full), referred to below, seems to support Dr. Kummerow’s assertion. Excerpt:

    Traditional Mediterranean, rural Japanese, and other populations with very low CHD risk have uniformly low LA intakes. Two US prospective cohort studies have reported inverse associations between LA intake and CHD risk. However, because LA intake was uniformly high, severalfold higher than evolutionary intakes and those of modern groups with very low CHD rates, these studies provide little insight into optimal LA intakes. Moreover, both studies relied on food frequency questionnaires, which have well-known limitations and may not be able to disentangle the effects of LA and n-3 ALA. Controlled trials in which high-LA oils replaced TFA- and SFA-rich fats have shown conflicting results, despite the fact that LA was accompanied by large amounts of medium- and long-chain n-3 PUFAs. A single small trial testing the specific effects of LA without n-3 PUFAs found increased CHD risk. The only long-term trial that reduced n-6 LA intake to resemble a traditional Mediterranean diet (but still higher than preindustrial LA intake) reduced CHD events and mortality by 70%. Although this does not prove that LA intake has adverse consequences, it clearly indicates that high LA intake is not necessary for profound CHD risk reduction. http://www.ncbi.nlm.nih.gov/pubmed/19627662

    In 2010, at the end of a meeting of the International Society for the Study of Fatty Acids and Lipids, the experts agreed on the need for “… a randomized con- trolled trial to compare the effect of low and high intakes of LA. The trial should have typical US intakes of ome- ga-3 PUFAs, with 7.5% energy from LA (the current US intake) in one group and 2.0% LA (historical intake) in the other. It would study cardiac endpoints and continue for about 5 years. http://www.karger.com/Article/Pdf/324749

    Hopefully, such a trial is in progress. Meanwhile, the biochemists have furnished some clues as to what is causing the inflammation that causes arteries to clog. Excerpt from Page 191 of The Modern Nutritional Diseases: and How to Prevent Them by Fred and Alice Ottoboni:

    excerpt from Page 191 of The Modern Nutritional Diseases: and How to Prevent
    Them by Fred and Alice Ottoboni

    BIOCHEMICAL
    LESSON: The significant point is that good health depends on regulating the D5D enzyme. High insulin levels due to dietary sugar and starch and high dietary omega-6 to omega-3 ratios, stimulate the D5D enzyme, and move the biochemical set point from normal toward inflammation. On the other hand, control of dietary sugar and starch, reduction of LA in the diet, and a daily supplement of fish oil to provide EPA will inhibit the D5D enzyme so that the appropriate amounts of both proinflammatory and anti-inflammatory eicosanoids are produced. Keep in mind that all of the eicosanoids, both the so-called good and
    bad, are important. The body is designed to use eicosanoids with opposing effects to control vital functions. In a state of optimum health, the good and the bad eicosanoids balance one another. http://www.amazon.com/The-Modern-Nutritional-Diseases-Prevent/dp/0915241056

    Fred Kummerow is 99, Fred Ottoboni is 86 and Alice Ottoboni is 91. I’m guessing these scientists know something.

  • http://www.the10principles.com/ the10principles

    As a teenager I set out to lose 10 pounds but I got so lost in the details. The result? I ended up gaining 20 more pounds (30 in total) that I lost and gained back 100′s of times over the 10 years that followed.

    It wasn’t until I went back to the basics (15 years ago) by eating balanced meals and doing regular activity (vs. over-exercising) that I lost the weight and food became a non issue. A healthy lifestyle is easy. We make it complicated.

    As a former chronic dieter I 100% agree with Marion Nestle’s conclusion (final 4 paragraphs).

  • http://www.stevenhamley.com.au Steven

    Hi Erik,

    The Hooper, et al meta-analysis found no benefit for CHD mortality or total mortality.

    They included the Oslo Diet Heart Study (the only trial that found consistent benefit), even though they didn’t consider it to be “free of systemic difference in care” and “free of dietary differences other than fat”.

    The Los Angeles Veterans Administration Trial found an almost significant decrease in CHD events and a significant decrease in CHD mortality, but the butter used in the control group was re-heated and so the control group had a vitamin E deficient diet.

    The Medical Research Council trial no difference, except a decrease in probable and possible angina, but bear in mind that this was an unblended trial.

    There were three other trials included in the Hooper, et al meta-analysis that suggested some harm: The Rose Corn Oil Trial, the Sydney Diet Heart Study and the Minnesota Coronary Survey (for women only).

    Before you may object to the vegetable oils back then being higher in trans fats, you should be aware that hydrogenated oils and/or junk food was generally restricted in the experimental group, but not the control group

  • MargaretRC

    I’ve been saying this for years. Sat fat is the problem and including good natural fats in your diet, saturated or not, helps make sure one doesn’t over eat anything. Sat fat is better for the heart than sugar, refined grains, or highly unstable poly unsaturated vegetable and seed oils. It’s about time this made mainstream news.

  • http://www.nutritionprescription.biz/ Michele Jacobson

    Then there is the 2009 Swedish study, one of my favorites, which states: “(d)aily intake of fruit and vegetables was associated with a lower risk of coronary heart disease when combined with a high dairy fat consumption,…but not when combined with a low dairy fat consumption..The diet-heart hypothesis from the 1950s stating that saturated fats lead to heart disease via blood lipid derangement is under re-evaluation.” One possible explanation offered up by the researchers is that “(m)any vitamins and other essential substances are fat-soluble, which might explain our finding of a preventive effect of daily fruit and vegetable intake only for individuals with a high dairy fat intake.”(Holmberg, Sara; Thelin, Anders; Stiernstrom, Eva-Lena. “Food Choices and Coronary Heart Disease: A Population Based Cohort Study of Rural Swedish Men with 12 Years of Follow-up.” International Journal of Environmental Research and Public Health. 12 October 2009.6, 2626-2638; doi:10.3390/ijerph6102626.)

    This seems to combine much of what Ms. Nestle is saying in todays column.

  • http://thejustaboutlifeblog.wordpress.com JAL

    “My guess: If you balance food intake with physical activity and are not overeating, the specific proportion of fat, carbohydrate, and protein won’t matter nearly as much.”

    Here, here, I couldn’t agree more. I’ve just started writing about this myself actually.

    Too many people get hung up on the fine details and lose focus of the big picture: the simple equation involving total calories in and total calories out (i.e. burned through doing exercise).

    Eat sensibly, do some exercise :)

  • Kevin Klatt
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  • http://macsmiley.tumblr.com/ MacSmiley

    And Ancel Keys lived to 100 on a Mediterranean diet while living in Italy.

  • David_Brown

    And, as noted above, the so-called Mediterranean diet is, almost by definition, low in omega-6s and added sugars.

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  • Nick Wilson

    Saturated fats are somewhat a problem but , If someone balance his/her diet and do exercise daily, then their will be no specific proportion of fats. So regularly Exercise. http://www.hghenergizerplus.com

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