Saturated Fat Shows Unexpected Benefit

Diana Parsell

It's been an article of faith in the medical community for more than 40 years that diets high in saturated fats put people at risk of heart disease. Most saturated fats boost blood concentrations of harmful, low-density-lipoprotein (LDL) cholesterol and lead to the buildup of plaque in arteries. So researchers at the Harvard School of Public Health were "surprised" by the results of a new study showing exactly the opposite effect in a group of postmenopausal women.

Dariush Mozaffarian and his colleagues examined the daily diets and coronary artery conditions of 235 U.S. women. The women's average age was 66 at the beginning of the 3-year study, and all had some plaque buildup at that time.

The scientists took X-ray images at 10 places along each woman's heart arteries at the start and end of the study. The women all provided comprehensive records of what foods they ate and how much, including details such as the kinds of oils used for frying and baking.

The researchers analyzed the women's intake of various nutrients in relation to plaque buildup during the study, adjusting for factors such as age, education, smoking habits, and use of medication. The X-rays after 3 years showed that those women who had regularly eaten the highest amounts of saturated fats had the least amount of additional plague buildup in their arteries.

The women who ate more saturated fat also had a healthier balance of good and bad cholesterols, as well as more desirable blood concentrations of various kinds of fats.

The body needs a variety of dietary fats for energy, for proper functioning of the body, and for processing the fat-soluble vitamins A, D, E, and K. But excessive saturated fat can increase blood cholesterol, which circulates through the body in molecules called lipoproteins. When cholesterol builds up on the lining of blood vessels—a condition known as atherosclerosis—it constricts blood flow and can cause heart attacks and strokes.

Saturated fats come from meat and dairy products, as well as oils in some tropical plants such as coconut and palm trees.

No single answer

The Harvard researchers also examined the women's carbohydrate intake in relation to plaque progression. The women with the highest amounts of carbohydrates in their diets over the 3 years had the most plaque buildup. This was especially evident among women who ate a lot of low-fiber carbohydrates and those who had less physical activity.

Mozaffarian says the results, published in the November American Journal of Clinical Nutrition, shouldn't be construed as an endorsement of diets that advocate eating high amounts of fats and avoiding carbohydrates.

The outcome does support the advice of nutritionists who argue that people should be careful about what kind of carbohydrates they eat, he adds. "The women [in the study] who ate carbs in the form of whole-wheat grains did fine," he says. "The problem was with women who ate highly-refined carbohydrates."

An important distinction in this study, Mozaffarian cautions, is that the participants weren't typical in a number of ways.

For one thing, all the women were postmenopausal. Moreover, three-fourths of them were overweight, and 40 percent were obese. A quarter had diabetes.

Other studies have shown that women generally experience changes in their lipid, or fat, levels as they age. Concentrations of good, high-density lipoprotein (HDL) cholesterol tend to decline after menopause, for example.

Most other dietary studies have linked saturated fat intake with high blood concentrations of bad LDL cholesterol. That effect wasn't seen in this study, however.

Another significant trait of the group that may help explain the results is that most of the women consumed relatively low amounts of fat compared with those in typical U.S. diets. About 25 percent of this group's calories came from fats, whereas the fat content of most U.S. diets may be 40 percent or more.

In the study, "the beneficial effects [of saturated fats] were the greatest in women with the lowest fat intake overall," Mozaffarian points out.

He speculates that similar antiplaque benefits might also have occurred if the women had eaten more heart-friendly monosaturated fats, such as in canola and olive oils, in place of the saturated fats, so long as overall fat intake was low.

Dietary mystery

What interplay of factors affected plaque formation among the menopausal women in the study is a "paradox" that can't be fully explained, lipid experts Robert Knopp and Barbara Retzlaff of the University of Washington in Seattle acknowledge in an editorial accompanying the published study.

Knopp says the answer probably lies in the specific combination of characteristics of the women in the group.

Most of them, he notes, were "sort of a model for metabolic syndrome"—a set of physiological conditions that puts a person at risk of diabetes and other diseases involving problems processing insulin. Furthermore, he points out, two-thirds of the women were taking hormone supplements.

Mozaffarian says the study highlights the complex way in which dietary fats interact, which is not well understood. "Fats are not just inert metabolic substances, they have wide-ranging metabolic effects in the body, and these effects are different for different kinds of fats," he says.

Also, he says, "there's greater appreciation today of the fact that the effects of dietary nutrients are different in different people."

The researchers were "initially surprised by the findings, but not so much so" after considering possible explanations, Mozaffarian says.

Results of studies of saturated fat intake and coronary artery–disease risk have been inconsistent. And most of those studies have focused on men, while the effects of diet on heart disease may differ in men and women.

The volunteers in the Harvard dietary study were a subset of women from six cities who were enrolled in a randomized trial designed to evaluate whether hormone replacement therapy curbs atherosclerosis. The results, which showed that female sex hormones did not prevent coronary artery disease in the postmenopausal women, were "a great disappointment," Knopp and Retzlaff note.

References:

Knopp, R.H., and B.M. Retzlaff. 2004. Saturated fat prevents coronary artery disease? An American paradox. American Journal of Clinical Nutrition 80(November):1102-1103. Available at http://www.ajcn.org/cgi/content/full/80/5/1102.

Mozaffarian D., E.B. Rimm, D.M Herrington. 2004. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. American Journal of Clinical Nutrition 80(November):1175-1184. Abstract available at http://www.ajcn.org/cgi/content/abstract/80/5/1175.

Further Readings:

Raloff, J. 2004. Fighting cholesterol with saturated fat? Science News 166(Oct. 9):238. Available to subscribers at http://www.sciencenews.org/articles/20041009/note13.asp.

______. 2003. Another way saturated fats can hike heart risks. Science News Online (April 5). Available at http://www.sciencenews.org/articles/20030405/food.asp.

______. 1988. A saturated fat to enjoy without guilt. Science News 133(May 21):332.

Sources:

Dariush Mozaffarian
Harvard School of Public Health
665 Huntington Avenue
Building 2, Room 315
Boston, MA 02115

Robert H. Knopp
Northwest Lipid Research Clinic
University of Washington
School of Medicine
325 Ninth Avenue, #359720
Seattle, WA 98104

http://www.sciencenews.org/articles/20041127/food.asp

Doesn't it just make you want to bang your head against a wall?



Maybe because they don't have a cause-and-effect relationship!

It's amazing how, if a study results do not agree with the pre-conceived ideas of the researchers, the researchers expend a lot of effort explaining away the results.

So now that a test of the high saturated fat = rapid cardiac damage and death theory has shown it false, will the scientists who have been predicting this outcome all along be noticed rather than ignored? Yeah, right!!
Nyah Levi
PS: There is no sorrow in my heart that that pseudo-scientist (i.e. bald faced liar) Ancil Keyes is finally dead.

There's something terribly wrong with the teaching of science in this country. If a study doesn't support their original assumptions, the researchers call it a paradox and ignore the evidence right in front of their eyes. Another problem is that those reporting these studies in the popular press haven't the background to see these problems and call the scientists on it. It's just pathetic!

Kind of makes you appreciate how essential instincts have allowed so many animals to stay alive and evolve over the years...

This is more of a mess for Harvard - no mention of Willett's findings that polyunsaturated fats are what everyone needs more of.

My, that is messy. Enough to get you to the grocery store and leave you frozen in your tracks, unable to recall what you actually eat anymore.

So, a few questions/comments related to this saturated fat issue...

- Can anyone who's been reading this thread say what happened to their own cholesterol on more/less saturated fat? (And would be helpful to know what the situation was with your intake of other fats - that is, were you careful about using cold-pressed polyunsaturates vs. junky heated oils and transfats etc.?)

- My own cholesterol (speaking mainly of the bad LDL here) first rose out of range as a teen after a year of dieting involving very, very, very little saturated fat. And very little fat outside of that... ate mainly 1,000 or so calories per day of green salads, fish and dry-grilled chicken, with likely a little olive oil... would only use lite dressing that was very low fat or would drizzle about a teaspoon of olive oil only on a meal-sized salad. No bread type products to speak of. Many years later, my cholesterol dropped when I started a thyroid hormone prescription. Has since crept up again, hard to tell over the years if it has anything to do with what I eat or don't.. no clear trends. (Am trying oat bran and phytosterols now, along w/niacin, to see if I can bring my cholesterol down.)

- I sometimes notice I feel better shortly after having saturated fat - this doesn't happen with other types. (Not certain if it's all types of saturated fats though.) Wonder if it does some blood sugar stabilizing... I tend to feel a little warmer, non-achy and might be getting some endorphins or similar out of the deal.

When I started Atkins my saturated fat intake went up a lot, my trans fat intake dropped alot. I changed out butter for margarine, started eating cheese, cream, fatty meats. My total cholesterol dropped 60 points to 199, my LDL cholesterol stayed about the same (under 120) and my triglycerides dropped a huge amount. My HDL went up some.

So, there is a lot of debate whether or not cholesterol is even a worthwhile predictor of anything, but if it is, then it appears that Atkin's and saturated fats improved things for me by a significant amount.

Recently I changed to a much higher fat version of atkins where I am trying to get 70-80% of my calories from fat. I'm sure my saturated fat has increased quite a bit. I haven't had any lipids tests since the change, I'll have to keep my eyes peeled from some store doing cheapie tests so I can see what the scoop is.

Nancy,

Can I ask background as to why you want to go to the ultra-high-fat diet? Are you aiming for more body fat loss this way - or trying to cut down on protein/carbs for another reason? (And, will you be limiting cals?)

Well the theory is that excess protein gets converted to glucose, whereas its a little harder to store fat you consume. The reason I'm trying this is because I stall out on Atkins. It seems to work insofar as it really kills my appetite probably because I'm in ketosis and I seem to be able to consume a few more calories than I was before.

Yes, I also limit carbs to about 20g per day and I'm trying to keep to about 1400 calories a day. I simply don't lose if the calories get too high, no matter what I eat.

I'm not positive it works better than high protein, lower fat, for me. I'm still experimenting with it.

Well, good luck - sounds interesting. I tend to feel better on a non-lowfat program, I know that.

You might find it of interest to test your blood sugars throughout the day... they have kits under $20 now, and test strips as low as 50 cents each. It's helping me figure some things out.. for instance, I can see that my blood sugar levels fall when I have coffee.

Another thing that's proven useful to me it to get a salivary cortisol test done (several places online you can order them yourself.. do at least two test periods in a day). Found out my cortisol's high at night when it's supposed to be low but low in the morning when it's supposed to be high. If I recall correctly (for instance, reading at www.mercola.com), excess cortisol can stimulate the burning of protein. (I'm taking 100-400 mg of phosphatidyl serine in the afternoon/evening to combat the cortisol rise.. so far am feeling better but it's early days yet.)

I eat plenty of satfat. I fry plenty of meat, and just generally ignore the chicken littles that warn of the poisonous nature of heating oils.

The study results are interesting and certainly not unexpected. The interpretation is the same old tired BS, showing the deep-rooted bias of the medical and nutrition community. There isn't a darned thing paradoxical about these results.

And since when is it allowed to say something ignorant like, "well, monounsats would have had the same effect"? Do the darned study if you want to make those conclusions!

I read the original article of Mozaffarian et al. and the editorial comment by Knopp and Retzlaff. There is none of the "antilowcarb comments" that Diana Parcell refer to in her popular article and it is impossible to know what comments are her own. I just get tired of seeing everyone here trashing every scientific article without ever reading them.

I think the authors (Mozaffarian et al.) give a non-biased and fair picture of their result (which is not always the case). For example the abstract conclusion is this:
In postmenopausal women with relatively low total fat intake, a greater saturated fat intake is associated with less progression of coronary atherosclerosis, whereas carbohydrate intake is associated with greater progression.
The end of the discussion is this:
... Our findings also suggest that carbohydrate intake may increase atherosclerotic progression, especially when refined carbohydrates replace saturated or monosaturated fats. Confirmation of these findings in other studies and examination of potential mechanisms and alternative explanations are warranted.

I think a lot of times we hear the reporter's bias who is reporting on some study. They're drawing conclusions the scientists didn't necessarily draw.