Worth a Closer Look: Dietary Fat and Stroke

by Ellen

When I see a headline blaming fat for poor health, I always want to read further.  In this culture of reduced-fat, ultra-processed, sugary foods, I’m amazed that fat still gets a bad rap.

Study after study condemns fat as bad for our hearts, our brains (stroke) and our waistlines.  Mostly I just get frustrated, because different kinds of fats are not equal. Those nasty, fake trans fats usually get lumped in with saturated fats, making the good saturated fats look really deadly.  In reality, the trans fats are the ones doing us in; saturated fats are necessary and healthy.

A New Study

Results of a new study about fat intake and ischemic stroke risk in post-menopausal women were presented at the American Stroke Association’s International Stroke Conference on Wednesday.  The exciting thing about this new study is that fats were broken down by type.  Dietary intake of monounsaturated fat, polyunsaturated fat,  saturated fat and trans fat were all examined separately and as a whole.

While the study has not yet been released, I was able to obtain an abstract of the information presented at the conference as well as a better reporting of the results:  Total fat, trans fat linked to higher incidence of ischemic stroke

Post-menopausal women who reported consuming the most daily dietary fat had a 40 percent higher incidence of clot-caused strokes compared to women who ate the least amount, according to research presented at the American Stroke Association’s International Stroke Conference 2010.

The incidence of ischemic stroke also increased by 30 percent in the quartile of women consuming the highest daily amount of trans fat (average intake 7 grams per day) compared to those who consumed the least (average 1 gram/day). Two common sources of trans fat are processed foods and fried foods.¹

The analysis included data from 87,230 participants in the Women’s Health Initiative Observational Study. The bottom line is that an increased risk for stroke was found in two groups of women:

  • Women who ate the most “total” fat
  • Women who ate the most trans fat

I am really looking forward to reading the actual study when it’s released.  In the meantime, I have some questions:

1) How many women in the “high total fat” category (upper quartile) consumed trans fats as part of their diet?  If a good proportion of these women ate trans fats, which were shown to be a risk factor for stroke, then it makes sense that high total fat would also be a risk factor.

2) We do find that women with the greatest total fat consumption had even more strokes (40% more clot-caused strokes) than those in the lowest quartile of fat-consumers.  How much trans fat did they eat? I would guess that a large proportion of women eating the most total fat also consumed trans fats.

3)  How many women with high fat consumption ate no trans fat?  No other individual category of fat consumption resulted in a raised risk for stroke, so is it plausible that amounts of combined saturated, polyunsaturated and monounsaturated fats somehow together raised risk?

4) Why do study results get reported before we can read the whole study?

The study authors do say that trans fat intake should be reduced:

“I think our findings support the American Heart Association recommendations for keeping trans fat intake at less than 1 percent of energy,” said Ka He, M.D., Sc.D., M.P.H., senior author of the study and associate professor of nutrition and epidemiology at the UNC Gillings School of Global Public Health.²

So, why do we still see headlines like this one, Study: High-fat diets raise stroke risk in women, if it’s really the trans fats to blame and not the other fats?  If there were something inherently bad about high consumption of fat, unrelated to trans fat consumption, would the authors point it out?  We need to see that study!

This post is part of Fight Back Fridays at Food Renegade.  Head over there for some great discussions.

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Sources:

1) Total fat, trans fat linked to higher incidence of ischemic stroke: EurekAlert, February 24, 2010.

2) Ibid.

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chanelle February 26, 2010 at 11:18 am

My friend was over and mentioned that a food made with cream was “so fattening.” In our culture, fat is bad and fat = fattening. No matter what the source. It will be interesting to see the results of this study.

BodyEarth February 26, 2010 at 1:55 pm

Chanelle,
I know that I used to feel that way about cream and butter, but I am much happier now!
I’m especially eager to see the conclusions the study’s authors draw from their results.

Christy February 26, 2010 at 7:08 pm

Whenever I read about fat I hear Susan Powter in my head “food doesn’t make you fat…fat makes you fat!”. It is a loud voice to silence but I am working on it!

BodyEarth February 26, 2010 at 7:39 pm

Hi, Christy.
I know exactly what you mean. I remember sitting in a restaurant about 15 years ago behind a man who was explaining to his friend that fat doesn’t make you fat, bread does. I smugly told my husband that the man was wrong; bread was just broken down into simple sugar, not fat, so how could it make you fat?!
I’ve found that when I cut out desserts but still eat lots of butter and cheese and cream, I don’t gain weight. I actually lose some weight. Although I’ve read through plenty of science that supports this effect, it helps to have actual “proof!”

Denise March 1, 2010 at 5:01 pm

http://news.bbc.co.uk/2/hi/uk_news/magazine/8543172.stm I thought you might find this article interesting. It both descirbes some of the benefits of omega 3 fatty acids and wonders if the health claims are being inflated by the media. One thing I noticed in the article was the link between grass fed beef and higher omega 3 content. This made me wonder if not only the presence of the nutrient but how natural the source of said nutrient was important in its efficacy.

BodyEarth March 1, 2010 at 7:12 pm

Thanks for the link, Denise! It looks like the article has some good points about health fads, but I like the comments section even better. For good health, the right balance of omega-3 fatty acids to omega-6 fatty acids is crucial, and the article doesn’t really address that issue. Also, the source of omega-3’s is really important: omega-3 fatty acids from fish/krill/cod liver oil (EPA and DHA) are much more available for use by the body than those found in flaxseed oil (ALA), which must first be converted to EPA and DHA, an inefficient business.
You’re right about “natural sources.” Beef from cows that eat grass, as they were meant to, is naturally higher in omega-3 fatty acids, as are eggs from chickens that are pastured.

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