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I've been taught since I was a kid that eating fat is bad for my health. Later on, I found out that unsaturated fats (especially ones containing Omega-3 and Omega-6) are actually good for your health.

Now I've heard that there's dispute among professionals on whether saturated fats are unhealthy. What's the evidence for either side?

I do realize that a balanced diet is probably good, and I assume that just about anything can be had in excess. If there's any information on what constitutes a moderate/safe amount, I'd be interested.

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You may be interested in the meta post on the health/medicine tags. – Jason Plank Mar 24 '11 at 2:15
I think you are confused about omega-6. I have heard that we consume way too much omega-6 and need to consume more omega-3. Omega-6 is plentiful in the plant based oils that people use instead of animal fats, since saturated fat is allegedly unhealthy (I however, think saturated fats are a very healthy source of calories). – Muhd Feb 15 '12 at 23:48

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Intake of saturated fat can raise one's blood cholesterol and increase the risk of developing coronary heart disease (the research is vast). There is no question that high blood cholesterol is a bad thing, but this does not mean eliminating or reducing saturated fat from you diet will necessarily lower or eliminate your risk of developing CHD or any other disease.

"Now I've heard that there's dispute among professionals on whether saturated fats are unhealthy."

1984: Meat consumption and fatal ischemic heart disease.

For 45- to 64-year-old men, there was approximately a threefold difference in risk between men who ate meat daily and those who did not eat meat. This is the first study to clearly show a dose-response relationship between meat consumption and ischemic heart disease risk.

Possible interpretation: Do not eat meat (or butter). Ever.

2010: Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat

...Reduced saturated fat (SFA) consumption is recommended to reduce coronary heart disease (CHD), but there is an absence of strong supporting evidence from randomized controlled trials (RCTs) of clinical CHD events...(1)

Possible interpretation: Eat as much meat as you want (with butter even).

The rub: Politicizing either interpretation is child's play (and I'm not gonna touch it*).

A good explanation and general summary of the state of fat.....

Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review

Key points from the paper:

  • In the past several decades, reduction in fat intake has been the main focus of national dietary recommendations to lower risk of coronary heart disease (CHD).
  • Metabolic studies have long established that the type of fat, but not total amount of fat, predicts serum cholesterol levels.
  • Results from epidemiologic studies and controlled clinical trials have indicated that replacing saturated fat with unsaturated fat is more effective in lowering risk of CHD than simply reducing total fat consumption.
  • Prospective cohort studies and secondary prevention trials have provided strong evidence that a higher intake of n-3 fatty acids from fish or plant sources lowers risk of CHD.
  • Recent national dietary guidelines have shifted the emphasis from total fat reduction to distinguishing different types of fat.

The bottom line: Moderation in all things seems good advice.

*It is usually a good idea to check out the authors’ responsibilities and/or acknowledgments section of any research papers you might read.

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Thanks for an excellent review of the question. I guess if it's controversial, there won't be a consensus on what is 'moderation'. – dancek Mar 24 '11 at 20:15
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"There is no question that high blood cholesterol is a bad thing" actually, there's a very big question about this, according to many people. See this study, available online, or this book. – Flimzy Nov 1 '11 at 4:36
A problem with so many studies is defining simple things like "what is meat" and "what is butter." If you take a group of people eating double whoppers daily over a 10 year period, you are likely to see bad results. You can easily (though irresponsibly) correlate those results to "meat." Yet if you take a group who eats a variety of meats and vegetables cooked at home, you'll more likely see cholesterol, blood pressure, and other measurements that are on target. Look into studies on 'primitive' diets, those lacking highly processed foods. – Rab Sep 11 '12 at 13:02
Food that are high in saturated fat tend to be ones that are high in calories and generally considered not good for you. You can eliminate saturated fats(or high fructose sugars) and still not eat healthy. But limiting your intake of them and eating a healthy diet are almost always good choices. – Chad Sep 11 '12 at 13:38
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How about this possible explanation: { 1. Ppublic education about the dangers of saturated fats cause those concerned with health to avoid saturated fat. 2. Those concerned with health take other measures to improve their health than avoiding meat; those not concerned with health take other actions than eating meat to damage their health 3. It looks like eating meat causes unhealthiness. } Isn't that just as likely in some of the cases of research showing one thing or another? – ErikE Jan 1 at 22:57
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up vote 4 down vote

According to Saturated Fat and Cardiometabolic Risk Factors, Coronary Heart Disease, Stroke, and Diabetes: a Fresh Look at the Evidence (Micha & Mozaffarian, 2010):

Based on consistent evidence from human studies, replacing SFA with polyunsaturated fat modestly lowers coronary heart disease risk, with ~10% risk reduction for a 5% energy substitution; whereas replacing SFA with carbohydrate has no benefit and replacing SFA with monounsaturated fat has uncertain effects. Evidence for the effects of SFA consumption on vascular function, insulin resistance, diabetes, and stroke is mixed, with many studies showing no clear effects, highlighting a need for further investigation of these endpoints.

Very recent Cochrane systematic review (Hooper et al., 2011) is going along the same lines

This review suggests that modified fat intake, or modified and reduced fat intake combined (but not reduced fat intake alone) are protective against combined cardiovascular events. No clear effects of these interventions on total or cardiovascular mortality were seen.

According to these sources saturated fats are fairly neutral, however it would be good to replace some saturated fats in the diet with polyunsaturated fats. I think especially notable point is that replacing saturated fats with carbohydrates offers no benefits re CHD.

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The original "fat is bad" dietary advice was based on the fact that people consume excess calories and fat is the densest (in calorie per unit weight or volume). Hence the widespread advice to eat less fat. As a social experiment this was a major failure as people in countries who issued the advice are a lot fatter than they were before the advice was issued. This was probably because of carbs-fat substitution made worse because fat suppresses appetite in a way that carbs don't. – matt_black Jan 8 '12 at 14:29
@matt_black: Do you have reference for the appetite suppressing effect of fat? I'm curious as that has been the claim of many lowcarbers, however I've understood that the lower appetite during lowcarbing comes from increased protein intake and steadier blood sugar. I do agree that the energy content of fat has been one of the reasons for demonizing it. Also the whole lot of fat causes heart disease claptrap that came originally from Ancel Keyes and the Seven Countries Study. – Illotus Jan 8 '12 at 15:07
This isn't an unbiased source but does quote some proper scientific studies: coconutresearchcenter.org/article10065.htm I don't have the originals to hand. – matt_black Jan 8 '12 at 15:22
@matt_black: Thanks, I'll check those out. – Illotus Jan 8 '12 at 15:42
up vote 4 down vote

Actually, researchers led by Dr. Ronald M. Krauss, of the Children's Hospital Oakland Research Center in California, compared data from 21 studies that included a total of nearly 348,000 adults, and found that there was no difference in the risks of heart disease and stroke between people with the lowest and highest intakes of saturated fat. The results were published in the American Journal of Clinical Nutrition in 2010.

Also, this article quotes a study in the New England Journal of Medicine which showed that subjects who were on the low-carb diet ate the most saturated fat (compared to those on the low-fat diet and the medditerranean diet) and ended up with the healthiest ratio of HDL to LDL cholesterol.

As quoted by Wikipedia, similar conclusions were reached by popular science writers: Gary Taubes ("Dietary fat, whether saturated or not, is not a cause of obesity, heart disease, or any other chronic disease of civilization.") and Micheal Pollan ("The amount of saturated fat in the diet probably may have little if any bearing on the risk of heart disease...").

The bottom line is: there appears to be no clear relationship between the risk of heart disease and the amount of saturated fat intake.

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