Most diet-conscious people today think of potatoes as “a starch.” They think that if you are having potatoes for dinner, you still have to add “a protein” to your meal. Yet potatoes are an excellent source of protein. Scientists have known that since the 1920s because of an interesting experiment that was done in Poland in 1925 and published in 1928 in Biochemical Journal. Thanks to the Internet, you can read the original article for yourself.
The researchers knew that populations that subsisted on a diet based heavily on potatoes seemed to be healthy and remarkably free of scurvy, beriberi, and pellagra—diseases that were known to result from vitamin deficiency. Some earlier work had suggested that potatoes can provide enough protein for human nutrition, and this study was intended to confirm those results.
For 167 days, the researchers fed a healthy young man and a healthy young woman a diet whose only significant source of protein was potatoes. Besides potatoes, the subjects ate fat and salt and a few apples and pears. They could also have the occasional cup of black coffee or tea with sugar.
The subjects thrived on this limited diet. Their health remained good and their weight remained stable, except that the man started losing weight toward the end of the study as he got more serious with his athletic training. Nitrogen balance studies confirmed that they weren’t having any trouble with protein deficiency. Most surprisingly, they didn’t get bored with their monotonous diet! To show that these results weren’t some sort of fluke, look at what happened when someone from the Washington State Potato Commission ate nothing but potatoes for 60 days.
At the end of the article, the authors thanked Dr. Casimir Funk, who directed the experiment. Funk was a superstar in the history of nutrition. In 1912, he published a landmark article describing how he had isolated thiamine, the chemical that is responsible for preventing and curing the deficiency disease called beriberi. That same year, he wrote another landmark article, which suggested that several epidemic diseases were actually the result of a deficiency of some vital chemical that was needed in only tiny amounts. He guessed that, like thiamine, the other chemicals would be amines, so he coined the term “vitamines.” After it turned out that some of these vital chemicals aren’t amines, the “e” was dropped, and they became vitamins.
As this study showed, potatoes contain plenty of protein. So the next time that you think you need to add “a protein” to your meal, eat a potato!