Fast Food and Coronary Artery Function
It has been known for a while that high-fat meals can temporarily impair artery function by causing constriction of the arteries. This is usually demonstrated in the arm (brachial artery) because that is the easiest to measure. It was also made famous in the movie The Gamechangers because it can impair function in an organ near and dear to men below the waist. But this is a temporary effect that may go away after a few hours, so you may wonder how important this phenomenon this really is healthwise.
This was answered in a study that looked at the effect of high-fat meals on coronary arteries, as reviewed in Dr. Michael Greger’s video “Exercising To Protect Your Arteries From Fast Food“. It turns out coronary artery function is also similarly impaired for a few hours . Such a meal can use up your entire “coronary reserve”, which is how much surrounding arteries can expand as needed if blood flow is restricted in an important one. The most important is the left descending coronary artery, aka “the widowmaker”. The study showed flow to be drastically reduced in this artery after a high-fat meal. Now imagine that you suddenly had to climb some stairs quickly or run to catch a train. Your heart races, but your coronary reserve is used up and your heart is no longer getting enough blood supply. This could trigger an angina attack or even a heart attack in people whose coronary arteries are already at risk due to plaque build-up.
The only good news is that exercise can temporarily mitigate this effect. About an hour of moderate exercise (like brisk walking) or 20 minutes of more intense exercise (like stair climbing), can offset the effect of a subsequent high-fat meal, but only if you do it less than about 18 hours before the meal [2,3]. You can also do the exercise up to about an hour after the meal, but it doesn’t sound like a good idea for someone with coronary artery disease to briskly go up stairs for 20 minutes right after impairing their coronary artery function with a high-fat meal.
When I saw the amount of fat in the meal given to the subjects, it seemed really high to me, but then I found out it was just a meal that might be realistically ordered at a fast-food restaurant. So I think perhaps the biggest takeaway message is to avoid such meals. For most of us there’s probably no harm once in a while as a “special treat”, but for those with coronary artery disease, especially if you’ve not been very active recently, even one such meal is not advisable.
- Hozumi, T, et al, “Change in Coronary Flow Reserve on Transthoracic Doppler Echocardiography after a Single High-Fat Meal in Young Healthy Men”, Annals of Internal Medicine, 2002.
- Teeman, C, et al “Postprandial Lipemic And Inflammatory Responses To High-fat Meals: A Review Of The Roles Of Acute And Chronic Exercise”, Nutrition and Metabolism, 2016.
- Cho, M, et al, “The Acute Effects Of Interrupting Prolonged Sitting With Stair Climbing On Vascular And Metabolic Function After A High-fat Meal”, European Journal of Applied Physiology, 2020.