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· Mo Yoder ·

When I first learned that Mo Yoder, Buhler, Kansas, had been a research subject involved in testing by the military during the Vietnam War, I had a bad feeling.
That’s because I recalled hearing stories of soldiers unknowingly being used as human guinea pigs while experiments were done on them testing hallucinogenic drugs.
I shuddered at the thought, but I wanted to talk to him about his experience.
Mo graciously agreed to be interviewed about his one and one-half year adventure that took place during 1964-65 while he and other conscientious objectors (COs) were research subjects at the US Army Medical Research and Nutrition Laboratory, Fitzsimons General Hospital, in Denver, Colorado.
Before asking Mo about the tests that had been performed on him after he volunteered for this duty, I wanted to understand his options back in 1964. I mean, I’m an organ donor but I’ll do that upon my death. I’m unlikely to offer my body to science until then.

To understand how Yoder chose to volunteer to be a research subject, it helps to look at his upbringing. Born and raised in Pennsylvania of Amish descent, and later becoming Mennonite, meant Mo was surrounded by a church community whose creed and principals forbade its members from taking part in war.
Yoder set off for Kansas to follow the wheat harvest at age eighteen. Four years later he traveled by train from McPherson to Kansas City for his government induction physical—which he passed.
At the time, most Mennonite COs chose to work in hospitals for their two-year obligation, but Yoder wasn’t intrigued by that. A hospital job was too ordinary for him, too much like a regular job. After Yoder learned from a minister about the opportunity to contribute to medical science by being a research subject, he was up for the challenge.
As mentioned earlier, the research program took place in Denver. It was on a military campus run by the Army in conjunction with the University of Colorado. The work was usually seven days a week, twenty-four hours a day. And because of this, the volunteers fulfilled their obligation six months earlier than the hospital orderlies who worked regular shifts.
All the tests were diet related. The first one was a high-gluten diet. Mo recalled the six week experiment: “I gained weight like a pig. They fed us well, lot to eat. We had to eat it all. Everything was monitored. We had to save everything that came out.”
“Save?” I asked for clarification.
Sure enough, Mo explained that everything was monitored which meant trips to town were a bit unusual. Mo and other test subjects would go into the men’s bathroom, excrete in a plastic bottle they carried with them, and walk out.
The nutrition and metabolism research project carried out in the Metabolic Ward was “designed to achieve complete control over the test subjects’ diet, fluid intake, activity, and to assure complete collections of excretory products.” (See link for more information about the program and footnotes. The Metabolic Ward)
“On one experiment they gave us a card to carry to prove we weren’t druggies, we had so many marks in our arms,” said Mo.
I asked Mo if his body had time to recover between tests. He explained that at the end of each experiment the men would take capsules that had a red dye. Once they passed the red dye in a stool then the men got time off. Sometimes, especially at Christmas, Yoder had the opportunity to return to Kansas. Since he owned his own car, he could hit the road and return to see the Inman gal he was dating, Karen Ann Kroeker.

Yoder also emphasized that the program required the men to get daily exercise. They walked hundreds of miles on the treadmill machine and played a lot of ping-pong and volleyball. Mo said he can still hear the words today: “Okay guys, get out there; you’ve got to play volleyball!”
Have you ever heard of someone having a Vitamin B6 deficiency? The potential dangers are many. To me, the most notable signs and symptoms include: mood changes that can contribute to depression, anxiety, irritability and increased feelings of pain; seizures; and high blood pressure levels which can ultimately lead to heart disease and stroke.
Yoder recalled that “during this Vitamin B6 deficiency test the monitor took our car keys away from us because they wouldn’t let us drive.” Mo said that at one point in the test he “flew off the handle pretty good. I was irritated at a guy and I was going to pick up a chair and hit him.”
“Did you?” I asked.
“I guess I calmed down,” Mo replied.
The most memorable study for Yoder utilized a high altitude chamber to determine how well the subjects could adjust to the sudden changes in altitude. After being flown to San Antonio, Texas, the tests were monitored at Fort Sam Houston.
This diet-related test took place while the test subjects were on a Coffeemate and Metrecal liquid diet. They had mixed teams of COs and GIs enter a high altitude chamber at three different elevations (6,000′, 11,000′, and 15,000′) for 48-hour periods.
After the GIs completed the lowest altitude they started congratulating one another, but by the end of the highest altitude they were promising each other to never volunteer again.
The first six hours at 15,000 feet were uneventful for Yoder but the remaining period of time he had a splitting headache. Another subject developed fluid in his lungs. Fortunately, the subjects were monitored by physicians and psychiatrists.
When Yoder felt his worst, the monitor asked him how he would respond to the enemy. Mo replied: “I’d let them get me.”
One visibly odd test required each man to swallow a tube so that one end remained temporarily in the small intestine. It was used to extract specimens for biopsies. When the men walked around in public with their tubes hanging out of their mouths, they must have been a sight! I wonder if they got a break from playing volleyball.
It’s safe to say that with the exception of the high altitude tests, the others were pretty dull and monotonous. But someone had to do it. Whether it was eating food with the taste and consistency of refined sawdust (Avocel) for a nine-week stretch, or eating unsalted food for two weeks, Yoder was disciplined and dedicated.
If you think Yoder’s alternative service stint was a piece of cake, consider this: When was the last time someone else decided what you were going to eat for meal after meal? Do you always eat all the food on your plate, including the crumbs? What if you were required to get up every day for an hour of exercise? Would you do it? How long would you relish getting poked for blood tests every day even when you weren’t feeling well? Though the research subjects had breaks from the testing and observation, the nearly constant monitoring took people with a strong state-of-mind.

I was surprised, yet pleased to learn from Yoder that COs were treated with the greatest respect during their entire eighteen months of alternative service. U.S. colonels, well-known scientists, and high ranking officials from all over the world visited the ward. The experimental studies were of international importance.
Mo summed up his thought process: “By testing things on me, the doctors might be able to discover something which would benefit others. It was a great experience. If you can contribute to mankind, that’s all well and good.”
And fortunately for Mo there have been no negative physical problems due to his time as a human guinea pig some fifty-four years ago although, with an infectious laugh, he claims “that’s the reason I am the way I am.”
Now that I know Mo’s story, I thank him for his service.
Until next time, happy writing and reading!
That was a great story about Mo. I have heard about other veterans used as guinea pigs but I have never met one. Keep up the good work. Tom
Tom, thanks for your encouragement. I was hoping you wouldn’t hold any ill will towards Mo. I like to think that everyone was just doing their best during an incredibly difficult time. Thank you for your military service. Jim
Nice blog today. Interesting character.
Yes, Mo sure is interesting! The stories we have to tell.
My husband was a CO. Mennonite and Amish don’t believe in going to war.
Linda, do you know if he had an interview in order to obtain his CO status?
Your article reminded me of a book I read a few years ago about the harrowing “starvation experiment” that was done in the mid 1940s with World War II era conscientious objectors at the University of Minnesota, in conjunction with military researchers. If you have not read this book, I recommend it as a comparison/contrast source for what you were able to learn from Mo about his experiences in Denver two decades later.
The book is titled, The Great Starvation Experiment, author Todd Tucker, University of Minnesota Press.
Rachel, thanks for your feedback. I just ordered the book. It sounds fascinating! Jim
Interesting story. You should do more like this.
Thanks for your encouragement, Phil!
Thanks for the story…It was insightful.
Thanks for your encouragement, Shara.
Hi Jim, interesting blog about Mo. It must have been a fairly scary situation even if he did have plenty to eat. Good for him for doing it. Sean
Sean, I learned that there’s a big difference between having enough of something to eat and having appetizing meals to eat. Mo said they each had a rubber spatula to make sure they ate all the crumbs as part of the dietary study. But agreed, much better than a starvation diet. Jim
Good work Jim. Mo was a good subject and well known in this area. A man of high integrity and role model for many who know him. I think it is that integrity that would be very important in carrying out experiments that some one else designs. How tempting it would be to cheat. Lewis
Lewis, I absolutely agree! Mo is the greatest guy. He’s a joy to be around. A brief phone call can easily turn into a phone marathon. And you’re right. Mo was totally dedicated to helping mankind during his research. He wanted to help improve the world by his sacrifice. I’m lucky to count him as a friend. Jim