Just one high-fat meal can alter proper blood vessel functioning, according to a UM cardiologist
Recently, Dr. Gary Plotnick, a cardiologist at the University of Maryland Medical Center and professor of medicine at the University of Maryland School of Medicine, published a study in the Journal of the American College of Cardiology which indicated that fruits and vegetables may reduce the immediate adverse effects of high-fat meals on blood vessels. We spoke to Dr. Plotnick about the study results and its implications.
Your recent study compared blood vessel responses in 36 volunteers after consuming a 900 calorie high-fat meal consisting of an Egg McMuffin, Sausage McMuffin, two McDonald's hash browns and a beverage. The volunteers received four weeks of daily supplementation with a fruit and vegetable juice concentrate (capsule). Can you tell us about the study and the implications?
This study was done to see if we could block the detrimental effect of a high-fat meal. Our goal was to evaluate the mechanism of a high-fat meal and learn whether we could block or at least blunt the effect by antioxidants because we assumed the bad effect of a high-fat meal was an oxidant stress and antioxidants might block that.
We know if the inner lining of a blood vessel is working well in an individual, that individual doesn’t develop hardening of the arteries, whereas it is known that people who eat healthy meals, like the Mediterranean diet, tend to have less cardiac events.
So we wanted to see if you ate healthy meals over a period of a month, would it blunt the detrimental effects of a high-fat meal. In order to look at that question we looked at phytonutrients in the form of pills that contain a lot of fruits and vegetables.
So our subjects took these phytonutrients over a month’s time in a randomized fashion. At the end of the month we had them eat that one single high-fat meal to see what the effect would be.
What was the result?
In fact, if you took these phytonutrients for a month you had a blunted effect, meaning that you may not have quite as bad an effect with the high-fat meal if you take the phytonutrients over a period of time prior to ingesting the meal.
Does that mean that you can eat high-fat meals as long as you take a fruit and vegetable capsule first?
No. I think people are looking for a magic bullet. People would like to say “Here, I’m going to take this pill and then I can eat whatever I want.” I think that’s a mistake. It’s better to have the appropriate diet. I think a well-balanced meal with fruits and vegetables is the way to go.
Plus, the calories are important. You can’t take pills and then go to McDonald’s (or any other fast food restaurant) and eat these excess calories because even if you don’t have this bad acute effect to the blood vessels, you have other effects — you gain weight so that puts you at high risk for multiple other reasons.
What about if you eat a lot of fruits and vegetables in general? Will that counter the effect of a high-fat meal? Is that just as good as taking a pill?
There are multiple nutrients in fruits and vegetables and you can most likely attain the same beneficial effect. In fact I think it’s more attractive to try to get the same effect by eating fruits and vegetables because there may be phytonutrients in those in addition to those found in pills. So we say “maybe your mother was right: you should eat a lot of fruits and vegetables.”
If you eat well-balanced meals with fruits and vegetables I think that will accomplish the same thing as the pills, and in fact it may accomplish more.
Also, taking high -dose vitamins may have long- term side effects whereas I think a balanced diet makes a lot of sense.
In the recent movie Super Size Me, the narrator/film director (Morgan Spurlock) ate a 30-day diet of McDonald’s food, which had a dramatic impact on his health. Doctors who monitored Spurlock in the movie seemed surprised at the quick negative effect of the food on his health — in 30 days he gained 25 pounds, his cholesterol levels rose 65 points and he damaged his liver. Are you surprised at this effect?
No, not really. In fact they should have expected those responses. We know that a high-fat meal has multiple effects. It increases a fat in the bloodstream called triglyceride. When the triglyceride levels are high, there may be acute detrimental effects on blood vessels that result. In addition, the metabolism of LDL, which is the bad cholesterol, is affected. That’s probably why, over time, the cholesterol went up.
These effects were not that unexpected with that amount of fat he had in his diet. Most people who eat and gain a little bit of weight usually don’t raise their cholesterol that much in a month’s time. But I think these responses were probably predictable. Perhaps the doctors were surprised at how fast it happened.
So what are the effects of a high-fat meal, even just one?
That’s actually what we studied. We did a test to look at the health of a blood vessel and what we found is that 3 to 5 hours after the very high-fat meal, the blood vessel’s function became abnormal.
Now that doesn’t mean if you have a single meal once in a while, you’re at risk. However, if you already have coronary disease and you eat that high fat meal, it’s possible during that period you could be at high risk of having a cardiac event.
For a normal, healthy person, one high-fat meal may not have any detrimental effect and you might be okay, but that may be true if you’re at high risk because of heart disease. But certainly, eating that way chronically, as a lot of Americans do, is detrimental.
But is this effect temporary?
Yes. It seems that the effect of one meal is probably gone in six hours.
Can you tell us more about how you check how healthy blood vessels are affected? What’s the name of this test and how does it work?
We use the Brachial Artery Reactivity Test (BART) that works by putting a stress on the vessel. It shows how a vessel would react to a normal situation and then whether a high-fat meal makes it respond abnormally. With the BART test, the way we see whether the vessel is working well is to stimulate it with increasing flow.
First we measure the size of the vessel using echocardiography (sound waves) and so we know the baseline size. Then we put a blood pressure cuff on the upper arm and blow it up for 5 minutes. When we release it, blood flow increases substantially. If the vessel lining is healthy, it releases a chemical called nitric oxide that makes the vessel enlarge. So we can image the blood vessel before we do anything and we can image it after we release the blood pressure cuff. If the vessel is normal, the vessel will enlarge by about 15 to 20 percent.
One of your earlier studies indicated that blood vessels do not dilate normally after a high-fat meal. This study, done in 1996, found that taking high doses of vitamins C & E right before a fatty meal may counter the effects of high fat on blood vessels. How did that study lead you to your most recent work?
The original study went back eight years ago. That study indicated that a high-fat meal makes the blood vessel respond abnormally. The question was, could we make the blood vessel respond normally by using vitamins or phytonutrients? Thinking the detrimental effect of the high-fat meal was an oxidant stress, we wanted to see if an antioxidant would block it so we initially evaluated high doses of vitamin C and E. And we found that if we took these vitamins immediately before eating the same high-fat meal, the bad effect seemed to be blunted. But that was just an acute effect. However, we didn’t know when to take them or at what dose. Plus we thought that it might be more important to see what the effect of healthy food was.
What are the trends in obesity in the United States today? Has the rate increased in the last two decades? And is this affecting both adults and children?
If you look at the weight of the population compared with 20 years ago we see a marked increase. The trends show a marked increase in obesity and weight gain. If you look at kids in school there’s also a marked increase in obesity.
The scary thing is children are becoming obese, and once you become obese as a child you set a life pattern for yourself. It’s very hard to lose weight long term. And even if you do lose your weight on a diet, what’s been found is the vast majority of people gain weight back unless they’re in a support group. Support groups do tend to help. If you are in support group, you usually will still gain weight back but not as much as you would otherwise.
Society has not done well by having oversized portions available at fast food restaurants. McDonald’s has decreased the super size after the movie was released. That’s wonderful. But the best thing would be for people to change their eating habits. People really need to change, and they need to be aware of what’s in these foods.
What’s your bottom line advice on eating habits?
Basically you want enough calories to maintain an ideal body weight but not increase your weight. If you’re heavy, decrease your intake of calories. And eat balanced meals with fruits and vegetables making up a large part of your meal. Make sense?
Yes. The answer seems so easy, yet it’s so hard for people to follow that advice.
People want a magic bullet. Food is great; it tastes terrific. It’s a large part of life and people would like to be able to eat whatever they want. But you pay a price. So you have to prioritize and balance things. Once in a while a high-calorie meal would be fine as long as it doesn’t become a habit. It’s your overall lifestyle that’s important.
By Michelle W. Murray