A recent study reported that l-carnitine supplements improved patient outcomes after heart attacks. The supplement readily available and is claimed to increase energy, weight loss, and athletic performance. Carnitine is also found in high amounts in red meat.
But wait! A week or so before this story appeared, another study was published that reported that bacteria in the gut of meat eaters converted carnitine into a compound called TMAO (trimethylamine-N-oxide) and that high TMAO levels were associated with heart disease.
They found that the gut bacteria in vegetarians did not make this conversion and concluded that regular meat eating, and especially red meat, with its high content of carnitine, was unhealthy.
I think this is just another attempt to discredit red meat. We’ve had studies that lumped red meat together with processed meats like hot dogs and luncheon meats. The people who ate red meat and hot dogs had poorer cardiac outcomes than those who ate chicken and fish. But the headlines claimed that it was the red meat that was the problem.
When researchers tried to separate red meat from processed meat, they found no effect of the red meat.
The TMAO study had a similar bias. The researchers said it showed a link between red meat and heart disease. But red meat isn’t the only food that contains carnitine or TMAO. Some fish have very high levels of TMAO, and its degradation products are responsible for the “fishy” smell of old fish. One study showed that of various foods, only seafood, but not meat, caused an increase in TMAO excretion.
But the researchers of the recent study didn’t mention fish, just red meat.
What does all this mean for us?
First, I’m not a big fan of nutritional studies. Many of the results are based on food-frequency questionnaires, in which participants are supposed to indicate how frequently during the past week, month, or whatever they ate certain foods. I can’t recall exactly what I had for breakfast, and I certainly can’t recall what I ate last week.
Further, there are many ways to interpret any diet. You can eat a healthy low-fat diet by eating mostly whole foods. You can also eat an unhealthy low-fat diet by eating mostly processed foods. You can eat a healthy low-carb diet by eating mostly whole foods. Or you can eat an unhealthy low-carb diet by eating a lot of low-carb snack bars and shakes.
So when researchers lump participants into groups and then analyze them statistically, what exactly have they shown? Sometimes not much.
Second, this is a good example of the media going wild with simplistic conclusions that the authors of the study may or may not have endorsed. If you see a story trumpeting the fact that whoopieberries reduce diabetes rates and the study was funded by the Whoopieberrie Association, you may suspect that the researchers were biased.
In addition, such studies often take the food in question, powder it, and feed very high levels of the powder to rodents or humans. Eating the food is probably not a bad thing to do, but it may not have the result shown in the study.
Third, no result is trustworthy before it’s been replicated by several different research groups. Sometimes results occur simply by chance, and until they’re consistently found, they can’t be taken too seriously.
Finally, if you’re a whiz at statistics, you can check the statistics used by the research groups. Some researchers simply put their results into some software program and don’t really understand the mathematical implications. For that matter, neither do I in many cases. Statistics is not my strong suit. So I have to hope they knew what they were doing.
But I think we shouldn’t be afraid of red meat, or deep-sea fish, or most real foods. We should use common sense. It’s probably not a good idea to eat 16-oz steaks every night, simply because that’s a lot of meat, and too much protein will convert into glucose and raise your blood glucose levels. If you test after large protein meals, you’ll find out how much meat you can safely eat.
As for carnitine supplements, I think the fewer supplements we take, the better. If you find some supplement really helps you, then go ahead and take it. But don’t believe the hype the supplement pushers will bombard you with.
Published On: April 30, 2013