A letter appeared in today’s New England Journal of Medicine from a group of Danish researchers who had traveled throughout the world and sampled McDonald’s French fries and KFC chicken for trans fats.

We determined the content of industrially produced trans fatty acids in 43 servings of fast foods bought in 20 countries between November 2004 and September 2005. We and our colleagues decided which cities to include in the study on the basis of planned visits for other purposes. The foods (chicken nuggets and french fries) were purchased from McDonald’s and KFC outlets.

They discovered great geographical disparity in the trans fat content of these same food purchased in different countries.

The content of trans fatty acids varied from less than 1 g in Denmark and Germany to 10 g in New York (McDonald’s) and 24 g in Hungary (KFC). Fifty percent of the 43 servings contained more than 5 g per serving.

Why the big difference in trans fat content from country to country? It’s all in the cooking oil.

The cooking oil used for french fries in McDonald’s outlets in the United States and Peru contained 23 percent and 24 percent trans fatty acids, respectively, whereas the oils used for french fries in many European countries contained only about 10 percent trans fatty acids, with some countries as low as 5 percent (Spain) and 1 percent (Denmark). At KFC, some values for trans fatty acid content were above 30 percent. Within the same chain in the same country, large variations in these values were observed — for instance, between KFC outlets in Hamburg and Wiesbaden in Germany and between Aberdeen and London in the United Kingdom.

The take home message from all this is that it is not only the carbohydrate content of French fries and breaded fried chicken, it is the trans fat content too. Especially in foods made outside the home. It’s easy to wolf down a chicken sandwich and an order of fries and come away with the effects of 20-30 grams of trans fats swirling in your blood. Data from the Zutphen Elderly Study published a few years back in Lancet showed that consuming 5 grams of trans fats per day increased the risk of developing cardiovascular disease by 25 percent. Now I’m not sure I buy those figures as being exact, but I do believe there is little doubt that trans fats cause problems and are best avoided. And 25-30 grams per day is a whopping large dose, but it is a dose being consumed by us and our children every single day that we and they eat at fast food franchise outlets.
My advice is to avoid McDonald’s French fries and KFC breaded chicken like death. But if you’ve just got to have some, well, make sure you get it in Denmark.


  1. A few thoughts concerning trans fats and saturated fats. First, the National Academy of Sciences stated that there was NO safe level of trans fats. People get concerned about PCB’s, Aspartame, the toxic waste dump a mile down the road, etc. However, here is an item that is known to be toxic, albeit as a long term poison. There is no urgency to ban it from the food supply, although I suspect it will gradually disappear due to consumer pressure.
    Which brings me to the other item. Unless you are able to eat entirely organic items that you grew yourself, it is going to be almost impossible to avoid some exposure to trans fats, for example when eating out or possibly in purchased grocery items especially baked goods, the best strategy to reduce their toxicity would be a low carb high fat diet, with the fats used being cold pressed monounsaturated like olive oil or almost completely saturated like coconut oil or palm kernel oil. These fats will hopefully crowd out the trans fats, which are typically monosaturated to nearly saturated, in your cellular membranes. Thanks for the space to express my ideas.

  2. I completely agree. There is no way of knowing what you are served when eating out.
    My husband has a very good cafe where he works, and as soon as he walks up to the line, the cook recognizes him and puts real butter on the grill. Everyone else gets partially hydrogenated soybean oil.
    I’m thankful for that thoughtful cook, but worried about everyone else.
    BTW, in Denmark, the pastries are made with genuine dark European chocolate and real cream. With the exception of their excellent potatoes, the Danes know how to eat well.

  3. I eat McDonald’s fries only as a treat about once a month or every other month.
    The rest of the time I prepare and pack both my lunch and my dinner to take to work.

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