Affordable and ubiquitous, gyudon beef-on-rice bowls are a go-to dish for many broke college students and busy businessmen. Those who hesitate are those who think the brown slivers of beef look unhealthy.

Gyudon chain giant Yoshinoya Holdings Co. is trying to allay concerns about the nutritional value of its dishes, on Wednesday releasing the findings of a study of people who ate gyudon once a day for an extended period.

Commissioned by Yoshinoya, the experiment found that eating gyudon beef daily for three months did not raise the risk of developing lifestyle diseases.

“We’re pleased to announce that consuming our beef for 12 weeks in a row did not cause our subjects to show any symptoms of heightened health risks,” the company said in a statement.

In the experiment, the 24 male and female subjects aged 20 to 65 were asked to consume the firm’s beef once a day for three months while going about their daily lives. Not all the subjects were in the best of health to begin with: Some had high blood sugar levels.

At the end of the period, Tokyo-based Chiyoda Paramedical Care Clinic put the subjects through a range of tests, from assessing changes in their weight, fat level and pulse to inspecting their blood and urine.

The tests revealed no significant increase in weight, fat percentage or pulse rate. The level of their cholesterol and blood glucose — organic molecules closely linked to problems such as metabolic syndrome — showed no worrying change, either.

Japan has witnessed a spike in people with metabolic syndrome as it shifts toward an Americanized, meat-oriented dietary culture, so a negative image has long permeated its gyudon bowls, Yoshinoya said.

It added, it hoped this study would “dispel” distrust of its products.

However, one medical expert was unconvinced. Yoshio Ikeda, a doctor who serves as chairman of Japan Preventive Association of Life-style Related Diseases, said the experiment’s methodology managed to meet only a “minimum” level of credibility.

Although describing the study’s findings as trustworthy, Ikeda cautioned that gyudon bowls served in Yoshinoya parlors were not necessarily harmless. The gyudon beef provided for the subjects weighed only about 65 grams each — about the same volume they would normally consume as a main or side dish.

“So all the subjects did is eat gyudon beef once a day in place of other types of meat” that they would have eaten anyway, Ikeda said.

It was “no wonder” that no significant change befell their body conditions, he said.

“People shouldn’t take the results as meaning that they are free to eat whatever size they want at Yoshinoya parlors,” he said. “The fact remains that devouring supersize gyudon on a daily basis will make you fatter.”

Yoshinoya said its findings did not vouch for the quality of all gyudon beef in the market — they apply exclusively to beef cooked in the proprietary broth prepared according to Yoshinoya’s own nutritional standards.

In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.