James Stangle, a doctor of veterinary medicine in South Dakota, has sounded the alarm on the Impossible Whopper, which, he says, contains so much estrogen that the mock-meat burger could grow breasts on men who wolf down too many of the Burger King sandwiches.

In a recent report for Tri-State Livestock News, Stangle crunches some serious numbers. He compares the estrogen levels found in the Impossible Whopper to those in the original Whopper, based on their protein sources (beef for the original, and soy for the plant-based one). The Impossible Whopper, Stangle concludes, has 44 milligrams of estrogen compared to just 2.5 nanograms in the beef Whopper.

“Now let me refresh your metric system,” Stangle writes. “There are 1 million nanograms (ng) in one milligram (mg). That means an impossible whopper [sic] has 18 million times as much estrogen as a regular whopper [sic]. Just six glasses of soy milk per day has enough estrogen to grow boobs on a male.”

It’s worth noting that Tri-State Livestock News is, according to its About Us page, a trade publication for the livestock industry, and the “growth and success of Tri-State Livestock News is due to the long-term support from the publication’s stockmen and agribusiness customer base.” As The Post’s Laura Reiley noted in a story this year, “Many of the country’s 800,000 cattle ranchers have declared war on newcomers Impossible Foods and Beyond Meat,” two of the leading companies responsible for plant-based meats. Impossible Foods supplies the patties for the Impossible Whopper.

It’s also worth noting that conservative news outlets, such as National File and MichaelSavage.com, have picked up on the story. “In short, the Impossible Burger is a genetically modified organism filled with calorie-dense oils that can make a man grow breasts if eaten in sufficient quantity,” wrote Tom Pappert, editor in chief of the National File.

Soy contains a high concentration of isoflavones, which according to an Environmental Health Perspectives report “belong to a class of compounds generally known as phytoestrogens.” According to Harvard School of Public Health’s Nutrition Source, these plant compounds are “similar in function to human estrogen but with much weaker effects.”

Fears over soy are nothing new, New York University nutrition professor Marion Nestle told The Washington Post on Thursday. She remembers reviewing a wealth of research material for her 2006 book, “What to Eat.” One book, she recalls, basically came to the conclusion that “soy is poison,” while another volume said that “soy is the best health food ever.”

Whether this is good, bad or indifferent depends entirely on who you read and what you read, Nestle said. There is an enormous, enormous, enormous amount of literature on soy estrogens, and it comes to sort of baffling conclusions. Some studies show harm, some studies show benefits. What do you do in a situation like that?

What you do, Nestle said, is look to cultures that have historically consumed soy products.

Asians have been eating soy products for millennia and don’t seem to be any the worse for it. They have among the longest lifespans and best health, at least in classic diets, she said. There is a special concern about . . . men and boys who eat soy products, but again, if you look at populations that eat a lot of soy products, there is no evidence of particular problems. No, they don’t grow breasts.

Nutrition Action, a resource website produced by the Center for Science in the Public Interest, noted that the soy scare may have originated with a 2008 report in a medical journal about a 60-year-old Texas man who complained of sore, enlarged breasts and a decreased libido. Blood tests showed his estrogen levels were up to eight times higher than those at the top end of the normal range, the site reported.

The man’s elevated estrogen was apparently caused by his consumption of soy milk. He allegedly drank three quarts a day, which, according to Nutrition Action, would have given him a daily dose of 360 mg of isoflavones, about 10 times what the average man in Asia consumes. When he stopped drinking soy milk, his estrogen levels returned to normal and his breast tenderness disappeared, the site reported.

The soy products that cause the most concern are soy-based infant formulas, which have become popular with parents for a variety of reasons. On its page about soy infant formula, the National Institute of Environmental Health Sciences notes that although there have been no specific health problems documented in human infants receiving soy formula, it is recognized that infants go through developmental stages that are sensitive to estrogens. Therefore, infants are more likely than adults to be vulnerable to the estrogen-like effects of the phytoestrogens in soy.

Animal studies, the page points out, indicate that health effects of possible concern include early onset of puberty in females and alterations in development of breast tissue. But the Harvard School of Public Health warns against giving too much credence to such studies: Soy may be metabolized differently in animals, so the outcomes of animal studies may not be applicable to humans. The school also notes that soy may be broken down and used by the body differently in different ethnic groups, which is why individuals from some countries who eat a lot of soy appear to benefit from the food.

So what’s the bottom line for human adults on soy products?

My take on soy products is that they’re foods like any other, and like any other, they should be eaten in moderation, said Nestle, the nutrition professor.

And what does moderation look like?

I was afraid that you would ask that, Nestle said. I don’t know. Once in a while. Not every day.

The Harvard school’s takeaway is this: Soy is a nutrient-dense source of protein that can safely be consumed several times a week, and is likely to provide health benefits — especially when eaten as an alternative to red and processed meat.

As Nestle puts it, Eating it once in a while is unlikely to be harmful. Eating it every day and having it as a main source of calories, I don’t know anybody who does that.

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