Here’s a question for you. What’s the best way to live a longer, healthier life? Diet? Exercise? Both—eating healthy while doing jumping jacks? Welcome to the Nutrition Facts Podcast. I’m your host Dr. Michael Greger and I’m here to help you answer that question. We have tremendous power over our health destiny and longevity. The vast majority of premature death and disability is preventable with a healthy enough diet and lifestyle. And, I’m here to bring you the latest peer-reviewed research to give you the tools to put it into practice.
Today vegetarian athletes are pitted against their meat-eating counterparts. In our first story we compare the diets of the Roman gladiator “barley men” to the modern Spartans of today.
Recently, the remains of dozens of Roman gladiators were discovered in a mass grave. The clue to their identities were the rather distinct types of mortal injuries they found, like being speared in the head with a trident. Using just their skeletons, they were able to reconstruct the death blows, show just how buff they really were, and even try to reconstruct their “diet of barley and beans.” You can look at carbon isotopes and see what kinds of plants they ate; “nitrogen isotopes reflect any intake of animal protein.” You can also look at the sulphur in their bones and the amount of strontium, leading commentators to submit that the best athletes in ancient Rome ate largely plant-based diets.
Then there were the legionnaires, the Roman army troopers, famed for their abilities, also eating a similar kind of diet, suggesting “The best fighters in the ancient world were essentially vegetarian.” So, if the so-called “perfect fighting machines,” the great sports heroes of the day, were eating mostly grains and beans, should that tell us anything about sports nutrition and the preferred diets of elite athletes? Well, most of the Greeks and Romans were “basically vegetarian” and centering their diets around grains, fruit, vegetables and beans, so maybe the gladiators’ diets weren’t that remarkable. Plato, for example, pushed plants, preferring plant foods for their health and efficiency.
So yes, “the Roman gladiators were known as the ‘barley men.’” But is that because barley gives you “strength and stamina”? Or was that just the basic food that people ate at the time, not necessarily for performance, but because it was just so cheap?
Well, if you look at “the modern Spartans,” the Tarahumara Indians, the ones that run races where they kick a ball for oh, 75 miles just for the fun of it, running all day, all night, and all day, maybe 150 miles if they’re feeling in the mood. What do you get if you win? “A special popularity with the ladies (although how much of a reward that would actually prove to be for a man who had been running for two days straight is questionable,” though maybe their endurance extends to other dimensions). “Probably not since the days of the ancient Spartans has a people achieved such a high state of extreme physical conditioning.” And what did they eat? The same kind of 75 to 80 percent starch diet based on “beans, corn, and squash.” And, they had the cholesterol levels to prove it, total cholesterol levels down at an essentially heart attack-proof 136. And it’s not some special genetics they have—you feed them enough egg yolks, and their cholesterol creeps right up.
Modern day Olympian runners eat the same stuff. What are they eating over there in Kenya? A 99 percent vegetarian diet centered mostly around various starches. But as in all these cases, is their remarkable physical prowess because of their diets, or in spite of their diets? Or have nothing to do with their diets? You don’t know…until you put it to the test.
“In spite of well-documented health benefits of more plant-based diets, less is known regarding the effects of these diets on athletic performance.” So, they “compared elite vegetarian and omnivore endurance athletes for aerobic fitness and strength.” So, comparing oxygen utilization on the treadmill, and quad strength with leg extensions. And the vegetarians beat out their omnivore counterparts for “cardiorespiratory fitness,” but their strength didn’t differ. Suggesting, in the very least, that vegetarian diets “do not compromise athletic performance.”
But this was a cross-sectional study. Maybe the veg athletes were just fitter because they trained harder? Like in the National Runners’ Health Study looking at thousands of runners: vegetarian runners were recorded running significantly more on a weekly basis; so, maybe that explains their superior fitness. Though, maybe their superior fitness explains their greater distances.
Other cross-sectional studies have found no differences in physical fitness between vegetarian and non-vegetarian athletes, or even worse performance, as in this study of vegetarian athletes in India. Of course, there could be socioeconomic or other confounding factors. That’s why we need interventional studies to put different diets to the test and then compare physical performance, which we’ll explore next.
In our next story, meat-eating athletes are put to the test against vegetarian athletes and even sedentary plant-eaters in feats of endurance.
In 1896, the aptly named James Parsley evidently led a successful vegetarian cycling club to victory. Their competitors evidently having to “eat crow with their beef.” Evidently some Belgian put it to the test in 1904, with those eating more plant-based supposedly lifting some weight like 80 percent more times, but I couldn’t find the primary source in English. This I could find, though: a famous series of experiments at Yale, published more than a century ago, on the influence of flesh-eating on endurance.
Forty-nine people were compared: regular athletes (mostly Yale students), vegetarian athletes, and then just sedentary vegetarians. “The experiment furnished a severe test of the claims of those flesh-abstainers.” Much to the researchers’ surprise, the results seemed to vindicate the vegetarians, suggesting that not eating meat leads to far greater endurance compared to those accustomed to the ordinary American diet.
The first endurance test was how many minutes straight you could hold out your arms horizontally: flesh-eaters versus flesh abstainers. The regular Yale athletes were able to keep their hands out for about 10 minutes on average. It’s than it sounds; give it a try. OK, but those eating vegetarian did like five times better. The meat-eater maximum, was only half that of the vegetarian average. Only two meat eaters even hit 15 minutes, whereas more than two-thirds of the meat-avoiders did. None of the regular diet folks hit a half hour; whereas, nearly half of the healthier eaters did, including nine that exceeded an hour, four that exceeded two hours and one guy going for more than three hours.
How many deep knee bends can you do? One athlete could do more than 1,000, averaging 383, but they got creamed even by the sedentary plant-eaters. That’s the crazy thing—even the sedentary abstainers surpassed the exercising flesh-eaters. The sedentary abstainers were in most cases physicians who sat on their butts all day. I want a doctor that that can do a thousand deep knee bends!
And then in terms of recovery, all those deep knee bends left everyone sore but much more so among those eating meat. Among the vegetarians, of two that did like 2,000 knee bends one went straight off to the track to run, and another went on to their nursing duties. On the other hand, among the meat-eaters: one guy reached 254, went down once more and couldn’t get back up, had to be carried away and was incapacitated for days, another impaired for weeks after fainting.
It may be inferred, without reasonable doubt, concluded the once skeptical Yale researcher, that the meat-eating group of athletes was very far inferior in endurance to the vegetarians, even the sedentary ones. What could account for this remarkable difference? Some claimed that flesh foods contained some kind of “fatigue poisons,” but one German researcher who detailed his own experiments with athletes offered a more prosaic answer. In his book on what looks like physiological studies of uber-driving vegetarians—I told you I only know English—he conjectured that the apparent vegetarian superiority was just due to their tremendous determination to prove their point and spread their propaganda; so, they just make a greater effort in any contest than do their meat-eating rivals. The Yale researchers were worried about this; and so, special pains were taken to stimulate the flesh-eaters to the utmost, appealing to their college pride. Don’t let those lousy vegetarians beat the “Yale spirit.”
The experiments made it into The New York Times. Yale’s flesh-eating athletes—sounds like a zombie movie—beaten in severe endurance tests. “Yale professor believes that he has shown definitely the inferiority in strength and endurance tests of meat eaters compared to those who do not eat meat.” Some of Yale’s most successful athletes took part in the strength tests, and Professor Fisher declares they were obliged to admit their inferiority. How has the truth of this result been so long obscured? One reason, Professor Fisher suggested, is that vegetarians are their own worst enemy. In their fanaticism, they jump from the premise that meat eating is wrong—often based on scripture or some kind of dogma—and jump from that to meat-eating is unhealthy. That’s not how science works, and such logical leaps get them dismissed as zealots, and prevent any genuine scientific investigation. Lots of science, even back then, was pointing a distinct trend toward more plant-based eating, and yet the word vegetarian—even 110 years ago—had such a bad, preachy rap that many were loath to concede the science in its favor. The proper scientific attitude is to study the question of meat-eating in precisely the same manner as one would study the question of anything else.
In our final story, plant-based eating is put to the test for athletic performance.
Historical examples of successful plant-based athletes range from the gladiators in ancient Rome to the Tarahumara Indians who run 160-mile races for the fun of it: six back-to-back marathons. But, they weren’t put to the test until the last century or so, purporting to show beyond a reasonable doubt that athletes who regularly ate meat showed “very far…inferior endurance” to even sedentary vegetarians—meaning it’s not like the veg athletes just won because they were training harder or something. There are certainly advantages to plant-based eating, like more antioxidants to combat “exercise-induced oxidative stress”, and the anti-inflammatory nature of many plant foods that may “accelerate muscle repair” and strength recovery. But, do you have to eat this way for years, or decades, or your whole life to get these apparent benefits?
What if you took a couple guys in Texas, eating their regular Texan diet, put them through “a maximal exercise test,” then asked them to cut out the meat for four days, told them about the existence of bean burritos, then after four days tested again, measuring time to exhaustion, ramping up the treadmill to see how many minutes could they go without collapsing. And there was a significant difference, favoring the vegetarian diet, boosting the time to exhaustion by about 13 percent. Each of the subjects, all five, “had a higher time to exhaustion…following the vegetarian diet.”
But, who can tell me the fatal flaw to this study? Anyone catch it? They were all in the same sequence—meat first then veg. And any time you do a test a second time, you may do better just because you’re more familiar with it. If they then went back to eating meat, and their performance tanked during a third test, then you might be onto something, but this isn’t very convincing. And even if the effect is real, it may not be the meat reduction per se, but a function of improved glycogen stores from eating more carbs or something.
If you put athletes to a vegetarian versus omnivorous diet for a 621-mile race—you’ve heard of a 5k? This is a 1000k!—and you make sure to design the two diets so they get about the same percentage of carbs, the finishing rates are identical, and total times within just a few hours of each other.
Same thing with sprinting: randomize people into veg or mixed diet groups, and no significant difference in sprint power between the two groups. They conclude that “acute” vegetarianism has no apparent adverse effects, but no apparent performance benefits either.
Same with strength training. Measure “maximum voluntary contraction” of both biceps and quads “before and after each dietary period,” and no significant difference either way. Put all the studies together comparing physical performance in these kinds of randomized, controlled trials, where you have folks eat more plant-based for just a few days or weeks, and: “There appeared to be no differences at least acutely between a vegetarian-based diet and an omnivorous diet in muscular power, muscular strength, or aerobic performance.”
Long-term, though, a plant-based diet can be conducive to both endurance performance and health. “Whereas athletes are most often concerned with performance, more plant-based diets also provide long-term health benefits and a reduction in the risk of chronic disease.”
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