Obesity Panacea

Are High Glycemic Index Carbs Worse Than Saturated Fat?

Posted by Travis Saunders on June 22, 2010
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Most people know that consuming too much fat, and especially saturated fat, is bad for your health.  That’s why there has been a concerted push for several decades to get people to reduce the amount of saturated fat that they consume, and to replace it with complex carbohydrates.  Now unfortunately people often misinterpret that to mean that fat is evil, but carbs are ok. This is problematic since consuming too many simple carbs is also likely to increase the risk of obesity, diabetes, and cardiovascular disease – exactly what we are trying to prevent in the first place.  So this raises the important question – in order to minimize the risk of heart disease, is it better to reduce the intake of saturated fat, or the intake of simple carbs?  An interesting new study in the American Journal of Clinical Nutrition examines this issue and while it doesn’t provide a definitive answer, it suggests that refined carbs are pretty bad indeed.

The new study was performed by Marianne Jakobsen and colleagues at the Aarhus University Hospital in Denmark, and it has a massive sample – 53,644 healthy men and women.  At baseline (from 1993-1997) these individuals completed a detailed questionnaire regarding their diet, physical activity levels, and other health-related variables including smoking status and socio-economic status.  These individuals were then followed until they had a heart attack, died, emmigrated, or until the end of the study in April of 2008 – whichever came first.

Using the diet questionnaires, researchers calculated both the amount of saturated fat and carbohydrate in the diet, as well as the quality of the carbohydrates being consumed.  This was done using the glycemic index, which measures the impact of a given carbohydrate on blood sugar levels.  For example, sugar and white bread are foods with a very high
glycemic index, vegetables like carrots or onions have a very low glycemic index, and foods like raisins and shredded wheat fall somewherein the middle (more details here).  What did they find?

During an average follow-up of 12 years, there were 1943 heart attacks in the study sample.  Simply swapping saturated fat for carbohydrates (e.g. a 5% increase in energy intake from carbs along with a 5% decrease in energy intake from saturated fat) was not associated
with any change in risk of heart attack.  However, swapping saturated fat for carbs with a high glycemic index (e.g. 5% lower calories from saturated fat, and 5% increased calories from high GI carbs) was associated with a 33% increased heart attack risk.  

Now I should mention a few things up front.  There was no intervention here, so people didn’t actually swap saturated fat for carbs for saturated fat – this was all calculated statistically.  That doesn’t mean I would discount these findings, but I think it’s worth mentioning. Also, diet was assessed once, using self-report, so it would be interesting to see if a similar study with a bit closer monitoring shows similar results.  The authors also mention several times of the “nonsignificant inverse association” between low-GI foods and heart attack risk (HR = 0.88, .72-1.07). With 50,000+ people it’s hard to argue that this study was under-powered.  But as I mentioned the measures of diet weren’t ideal, and this is where I think another study
with more direct measurement could be of real use.  

So what’s the take home message? 

Previous studies have suggested quite clearly that consuming too much saturated fat is a bad thing.  But not surprisingly, swapping out that saturated fat for carbs with a high glycemic index isn’t such a great move either – it’s essentially trading one crappy food for another. Frank Hu lays out an excellent prescription in an accompanying editorial. In it, he suggests that excessive intake of refined carbs (and especially sugar-sweetened beverages) represent the “perfect storm” for increasing risk of chronic diseases.   Fortunately, he points out that many dietary strategies can reduce the intake of refined carbs – for example:

…replacing carbohydrates (especially refined grains and sugar) with unsaturated fats and/or healthy sources of protein and exchanging whole grains for refined ones…

And

limiting sugar-sweetened beverage consumption, a major source of dietary [glycemic load] and excess calories, has been associated with lower risk of obesity, type 2 diabetes, and IHD.

Or

A very-low-fat, high-carbohydrate diet (eg, percentage of energy
<20% from fat and >70% from carbohydrates), once typical in traditional Asian populations, has the potential to be cardioprotective if most of the carbohydrates come from minimally processed grains, legumes, and vegetables and if the population is lean and active (and thus has low insulin resistance)…

And finally

a diet with moderately restricted carbohydrate intake but rich in vegetable fat and vegetable protein improves blood lipid profile and is associated with lower risk of IHD in the long term.Benefits of the plant-based, low-carbohydrate diet are likely to stem from higher intake of polyunsaturated fats, fiber, and micronutrients as well as the reduced GL in the
dietary pattern.

So it really comes down to what
many people have been saying all along – aim for a diet high in plants,
low in refined foods and saturated fat, and limit your intake of sugary
beverages.  And if you’re trying to reduce the amount of saturated fat
in your diet, make sure you’re not simply replacing it with refined
carbs.

Travis

ResearchBlogging.orgHu FB (2010). Are refined carbohydrates worse than saturated fat? The American journal of clinical nutrition, 91 (6), 1541-2 PMID: 20410095

Jakobsen MU, Dethlefsen C, Joensen AM, Stegger J, Tjønneland A, Schmidt EB, & Overvad K (2010). Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index. The American journal of clinical nutrition, 91 (6), 1764-8 PMID: 20375186

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Comments

  1. #1 Steve Parker, M.D.
    June 23, 2010

    Saturated fats are bad for your heart?

    Not according to an article in the January, 2010, issue of American Journal of Clinical Nutrition:

    Siri-Tarino, Patty, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, January 13, 2010. doi:10.3945/ajcn.2009.27725

    -Steve

  2. #2 Travis Saunders
    June 23, 2010

    This is outside of my area of expertise, so I’ll claim ignorance – although there was an editorial in AJCN in February which critiqued this article quite heavily, as well as another review in JAMA which suggests there is good evidence behind the health impact of swapping saturated fats for unsaturated fats. I’m sure there are people out there that know more about this than me, so I’d love to hear what they have to think.

  3. #3 Steve Parker, M.D.
    June 23, 2010

    For anyone with a little extra time on their hands, here are a few more scientific articles questioning the idea that saturated fats cause heart disease:

    Skeaff, C. Murray and Miller, Jody. Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials. Annals of Nutrition and Metabolism, 55 (2009): 173-201.

    Halton, Thomas, et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. New England Journal of Medicine, 355 (2006): 1,991-2,002.

    German, J. Bruce, and Dillard, Cora J. Saturated fats: What dietary intake? American Journal of Clinical Nutrition, 80 (2004): 550-559.

    Ravnskov, U. The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. Journal of Clinical Epidemiology, 51 (1998): 443-460.

    Ravsnskov, U. Hypothesis out-of-date. The diet-heart idea. Journal of Clinical Epidemiology, 55 (2002): 1,057-1,063.

    Ravnskov, U, et al. Studies of dietary fat and heart disease. Science, 295 (2002): 1,464-1,465.

    Taubes, G. The soft science of dietary fat. Science, 291 (2001): 2535-2541.

    Zarraga, Ignatius, and Schwartz, Ernst. Impact of dietary patterns and interventions on cardiovascular health. Circulation, 114 (2006): 961-973.

    Mente, Andrew, et al. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease. Archives of Internal Medicine, 169 (2009): 659-669.

    Parikh, Parin, et al. Diets and cardiovascular disease: an evidence-based assessment. Journal of the American College of Cardiology, 45 (2005): 1,379-1,387.

    Bray, G.A. Review of Good Calories, Bad Calories. Obesity Reviews, 9 (2008): 251-263. Reproduced at the Protein Power website of Drs. Michael and Mary Dan Eades. [Perhaps this doesn’t belong here.]

    Hooper, L., et al. Dietary fat intake and prevention of cardiovascular disease: systematic review. British Medical Journal, 322 (2001): 757-763.

    Weinberg, W.C. The Diet-Heart Hypothesis: a critique. Journal of the American College of Cardiology, 43 (2004): 731-733.

    Mozaffarian, Darius, et al. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. American Journal of Clinical Nutrition, 80 (2004): 1,175-1,184.

    [Related editorial: Knopp, Robert and Retzlaff, Barbara.
    Saturated fat prevents coronary artery disease? An
    American paradox. American Journal of Clinical
    Nutrition, 80 (2004): 1.102-1.103.]

    Yusuf, S., et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet, 364 (2004): 937-952. [ApoB/ApoA1 ratio was a risk factor for heart attack, so dietary saturated fat may play a role if it affects this ratio.]

    Hu, Frank. Diet and cardiovascular disease prevention: The need for a paradigm shift. Journal of the American College of Cardiology, 50 (2007): 22-24.

    [Dr. Hu de-emphasizes the original diet-heart
    hypothesis, noting instead that “. . . reducing dietary
    GL [glycemic load] should be made a top public health
    priority.”]

    Oh, K., et al. Dietary fat intake and risk of coronary heart disease in women: 20 years of follow-up of the Nurses’ Health Study. American Journal of Epidemiology, 161 (2005): 672-679.

    I’m suggesting that one of the most remarkable discoveries in the area of nutrition science over the last 40 years is that dietary total and saturated fat have little to do with coronary heart disease.

    I grant you that a few studies suggest replacing saturated fat with polyunsaturated fat tends to reduce heart disease.

    I’m not a bench scientist; I’m a clinician. I spent about 80 hours last summer reviewing the pertinent literature. Could I be wrong? Sure, but I don’t think so.

    -Steve

  4. #4 Christina RD
    June 23, 2010

    I have read comments from some health professionals and members of the public that have suggested that people like the idea that saturated fat is not harmful to your health. We know the top sources of saturated fat in the Canadian diet are:
    high fat processed meats such as sausage, bologna, salami and hot dogs
    • fatty meats such as prime rib and regular ground beef
    • full fat dairy products such as whole milk, high fat cheese, cream, and butter
    • coconut, palm, palm kernel oil
    • lard

    In addition to saturated fat the above includes high sources of calories, fat, sodium, and nitrites. There are other reasons to limit these food choices.

  5. #5 Dr. Lavinia Rodriguez
    June 23, 2010

    If we all focus on increasing our nutritional intake we automatically decrease saturated fats and high glycemic foods as well as make other healthful changes. The question of whether saturated fat is bad for us or not can continue to be an intellectual question until it’s proven one way or another, but eating nutritiously will be good regardless.

  6. #6 Harlan
    June 23, 2010

    I believe there’s also a newish argument that the badness of saturated fats has a lot to do with the Omega-3/Omega-6 ratio, which has a lot to do with the food eaten by the animals whose meat or milk is the source of the fat. So if you’re eating fatty meat from pastured (not grain-fed) animals, you’re in much better shape than someone who’s eating lean mean from grain-fed animals. It’s all a tradeoff. I’d rather eat salt and (healthier) fat than more sugar and other highly processed foodstuffs.

  7. #7 x-ine
    June 23, 2010

    I’m growing weary of the saturated fat vs. refined sugars battle. Focusing on one single culprit is ineffective when we know that there are a myriad of factors that can contribute to chronic disease. With regards to diet, we know that the quantity and type of fat, quantity and type of sugar, quantity of sodium, and the quality of foods can play a role. Instead of pin-pointing single factors, we really need to start taking a more holistic approach.

  8. #8 Travis Saunders
    June 23, 2010

    That’s a great point. Whether sugar or saturated fat is worse doesn’t really matter – reducing your intake of refined foods, sugary drinks, and animal products (and upping your intake of plant-based foods) will deal with pretty much all the issues you mentioned.

  9. #9 Andreas Johansson
    June 24, 2010

    minimally processed grains

    I note that spaghetti has one of the lowest GI values in the table Travis links to. Surely spaghetti is anything but minimally processed? Or is there a non-GI reason it’s bad for your heart?

  10. #10 Keith Grimaldi
    June 24, 2010

    Good post highlighting a very good study. The AJCN study was also interesting but the conclusion about sat fats being neutral was not really valid as has been discussed elsewhere. The study sponsors included the Dairy Council – doesn’t necessarily mean anything but it would have been better if it was completely independent. Nutrition studies are notoriously difficult to construct, carry out and interpret which is why we have every possible combination from sat fats=great to sat fats=evil, and the same for every other food or beverage (caffeine/coffee probably comes out on top for being good and bad for everything it has been linked to).

    there has been much talk about the human genome project and developing new drugs. The real promise will be in developing better nutritional studies and hopefully also getting better data from the well-designed studies already performed (e.g. the SELECT trial claimed no benefit for Vitamin E/selenium re prostate cancer, but a genetic stratification revealed selective benefits (see http://bit.ly/a6s4Ku). Together with powerful monitoring of metabolism with nutrigenomics tools (to reinforce/replace error prone dietary assessments) the genetics will hopefully bring some much-needed clarity to the field

  11. #11 Keith Grimaldi
    June 24, 2010

    PS – another study I discussed (at http://bit.ly/d1gn2h) was interesting and relevant to this discussion. The authors described their diet as the “Low Carb Med” diet and found it to be better than the traditional Med or the ADA diet. The study was pretty good but they were a bit disingenuous with the diet description – Low Carb Med is catchy and tunes in with this tiresome (as alluded to by x-ine above) low-carb vs. low fat argument, the better description of the diet is the less catchy but more accurate low GI/high MUFA diet – this embraces everything – refined carbs, low GI carbs and all fats – there is no one-trick diet

  12. #12 WIll
    June 24, 2010

    Grains can be sustaining, but ultimately, except in small amounts, I don’t think they are nutritious. Grains need to be near the top of the food pyramid. Eat butter instead.

  13. #13 Travis Saunders
    June 24, 2010

    Can I ask why?

  14. #14 x-ine
    June 24, 2010

    Butter > grains? Energy-density wise, yes. Whole grains are a good source of fibre, which is beneficial for our digestive tracts. A healthy gut means a healthier body, yes? Not sure why all grains are lumped into the same category of “not nutritious.” What’s wrong with whole wheat, quinoa, or kamut, to name just a few?

  15. #15 Lou Doench
    July 7, 2010

    “Grains need to be near the top of the food pyramid. Eat butter instead.”

    Mmmmmm… Buttered Grains…

  16. #16 Tyler
    July 7, 2010

    Hi Travis. I’ve run into these people before, that claim that saturated fat is good for you, and vegetable fats are bad.

    Its pretty easy to debunk, but its very pervasive because it has a lot of emotional power(we SHOULD eat more bacon? YESPLXKTHXBAI).

    The worst offender is here: http://www.fathead-movie.com/index.php/no-bologna-facts/

    Going from top to bottom:
    -Wrong. Many studies are available.
    -Mid 1900′s? Strange phrasing. Does he mean 1950′s? Does he mean 1905? Either of those, however, is incorrect, as animal consumption(as well as animal fat) has been on the increase for over the last century in the western hemisphere.
    -No study link?
    -I’m pretty sure these high rates of heart disease are due to genetic factors, which is a pretty blatant twisting of facts.
    -A congressional committee informed by many dietitians.
    -I thought the brain was made of neurons, not fat? Oh maybe he means the myelin sheath on neurons? How can we tell? Its such a blatantly twisted and unsupported statement.
    -Study please?
    -Study please?
    -Only correct statement he’s made here.
    -Testosterone has almost no connection to sexual performance… it does start the erection process as I understand it, but only a minimal amount is needed.

    These were things I found by actually looking at the science(papers mostly), with a basic knowledge of biology and chemistry. The documentary itself is even worse.

    Shortline: Saturated fats are still bad for you, but as this study indicates, not AS bad as refined carbs. Thats not necessarily a good distinction, as saturated fat is still very bad for you.
    -

  17. #17 rhonan
    July 7, 2010

    @Andreas Johansson: Spaghetti has a poor score on the Glycemic Index because it is made of pasta, which is mostly starch, and very high on the Glycemic Index, and tomatoes, which are actually on the high end of the Glycemic Index for vegetables, without much fiber to balance it off.

    The healthiest way to consume grain requires that the grain be first fermented, and possibly distilled. In moderation, it is a way to capture the healthful attributes of the grain, without the excess sugars and starches that can be so detrimental to good health.

  18. #18 theshortearedowl
    July 9, 2010

    The healthiest way to consume grain requires that the grain be first fermented, and possibly distilled. In moderation, it is a way to capture the healthful attributes of the grain, without the excess sugars and starches that can be so detrimental to good health.

    …like whiskey? I’m off t’ pub!

  19. #19 Chris
    July 15, 2010

    @rhonan: Wait, what? Spaghetti on the page linked to has a GI of 30, which is *LOW* (i.e. good for you), comparable to whole beans or lentils or All-Bran cereal. That’s what’s odd. Fettucine is also down there in the 30s (32).

    Both plain fettucine noodles (no sauce) and plain spaghetti (ditto) are almost entirely made of processed wheat, although it’s usually a relatively high-protein type of wheat. I can’t tell from the referred page whether the GI values are for the plain noodles or for noodles mixed in with sauce, meatballs etc. but I’d think if it was the latter they’d say so. If it’s the former, it’s definitely counter-intuitive that a highly processed wheat product could score so well.

  20. #20 Marty
    July 20, 2010

    @chris and rhonan: the list is a bit odd–Snickers Bar, corn chips and–please note, Travis–Nutella are all listed as low GI, too. Is this list very reliable?

  21. #21 LQ
    July 26, 2010

    @Marty Given the other things you listed, I can only assume they do mean “spaghetti with meat sauce,” because the other items all have fat and either fiber or protein (nuts).

  22. #22 Kate
    August 3, 2010

    yes Marty, chocolate bars or Nutella aren’t really high GI, but it doesn’t mean they are healthy.

  23. #23 Parker
    December 13, 2010

    I think it all has to do with the balance of carbs and sat. fats… You can’t just binge on fats and cut out carbs… your arteries will clog…

    but you can’t carb it out to the max, or your pancreas will explode! Dilemma… Dilemma….

    How bout just a balance diet…