Fears about hormones in beef production are completely unwarranted, says the science director of the Beef Cattle Research Council.
“There are no health risks associated with growth promotants, but producers spend a lot of time answering the public’s questions to explain the facts and dispel some of the myths,” Reynold Bergen said during a recent Beef Cattle Research Council webinar.
Hormonal implants in cattle have been around for about 60 years and contain natural and synthetic hormones, he said. They have been rigorously tested for efficacy and are safe for humans and animals, he said.
Common hormones include progesterone, estrogen, and testosterone; and are administered in a small pellet implanted between the skin of the ear and the cartilage. The implants dissolve very slowly over time, releasing a small amount of hormones that boost growth rates.
They do not end up in the food chain following slaughter, said Bergen.
“If there were any residual hormones in there, it wouldn’t find its way into meat,” he said.
According to a recent survey done by the Western Beef Development Centre, about a third of cow-calf producers use implants on a regular basis. A set of ear implants that would commonly be used in a feedlot situation contains 200 milligrams of trenbolone (a steroid used in beef cattle to increase muscle growth and appetite) and 20 milligrams of estradiol (estrogen).
That implant would last a feedlot steer for 120 days and would have no effect on a human, who produce more hormones in a single day than they could possibly absorb from beef, said Bergen.
“A prepubertal boy produces so much estrogen on his own that he would have to eat eight entire cows’ worth of beef every single day to get as much hormone as he is already producing. An adult female would have to eat 95 cows’ worth a day to replace what she is already producing,” he said.
Many plant and animal foods naturally contain hormones and estrogens with hormonal activities.
“Those are called phytoestrogens and so you hear the comment that the bun has more hormones than the burger and that’s true,” he said.
Some foods may contain more hormones than beef, but there is no cause to worry about those, because of a concept called ‘oral bioavailability,’ which means that it is easier to absorb hormones when they are injected rather than ingested orally, he said.
“If you eat hormones, only a tiny fraction of it ever reaches the tissue,” said Bergen. “The other 90 to 95 per cent gets broken down and inactivated in the digestive tract and liver, and it never reaches your tissues. That’s why bodybuilders inject themselves with this stuff rather than eating implants.”
The fear that beef hormones can cause early puberty has been dispelled by a number of studies, he added. In one study, pigs — who have digestive systems, anatomy and physiology similar to humans, — were given four different diets. The control group was given a diet of corn and canola meal. One group was given 200 grams of tofu burger every day, while the third group was given a quarter-pound burger from an implanted steer, and the fourth a quarter-pound burger from an unimplanted steer.
The piglets were fed this diet until they reached puberty, when their blood was monitored for hormone levels. They were then slaughtered and their reproductive tracts were measured. The scientists found no difference between the control and the pigs that had been given the unimplanted beef burger. The pigs that had received the implanted beef burger had low levels of estrogen activity, while the tofu burger diet had the highest level of estrogen activity, due to the phytoestrogens in tofu. (Phytoestrogens are much weaker than human estrogen, and do not pose a health risk to humans.)
“Even when there was a different level of estrogen in the diet, there was no difference as to when those pigs came into puberty,” said Bergen. “That goes back to bioavailability. When you eat hormones, 95 per cent of them get broken down before they reach the body.”
Nor were there any differences in the weight of the pigs, muscling, fatness, and serum progesterone and serum estrogen levels.
“Their conclusion was that these pigs could eat a quarter-pounder every single day and they’re not going to hit puberty any faster. And pigs are very similar to people and so this same thing is true for girls as well.”