Two slices of white bread has 45,000 nanograms of estrogen; a serving of implanted beef has two. Photo: Dr. Reynold Bergen
Canada’s Beef Cattle Research Council (BCRC) has collected some interesting stats on the estrogen level in beef.
A 75-gram serving of beef from cattle treated with hormone implants contains two nanograms (ng ~ one billionth of a gram) of estrogen.
“A person would need to eat 3,000,000 hamburgers made with beef from implanted cattle to get as much estrogen as the average adult woman produces every day, or 50,000 hamburgers to get as much estrogen as the average adult man produces every day,” says BCRC’s science director, Dr. Reynold Bergen.
“Beef is a really excellent source of protein, zinc, iron and a lot of other essential nutrients. It’s a really poor source of hormones.”
Considering there are about 45,000 ng of estrogen in 75 grams of white bread, the bun probably has far more estrogen than the beef!
If you need an explanation to go with the stats, the short of it is that cattle, alongside people and all other animals and plants, naturally produce hormones that are vital to growth, development and health. That’s why meat and plants can never be hormone-free.
Some of those natural hormones are steroid hormones, which are nothing more than a class of hormones that have the distinct four-ring nuclei known as a steroid nucleus. The word “steroid” comes from cholesterol because the hormones are derived from cholesterol and transported in the bloodstream to do their work in other parts of the body.
Promoting beef as raised without the added use of hormones and steroids seems rather redundant as far as beef production goes, Bergen says.
The long of it
Cortisol, primarily produced in the adrenal cortex, isn’t used to improve feed efficiency or growth in beef cattle, but is one of the most commonly prescribed steroid hormones in human medicine because of its anti-inflammatory and immunosuppressive effects.
Estradiol (an estrogen) and progesterone (a progestin) are the two female sex hormones produced in the ovaries. Oral contraceptives are synthetic versions of these steroid hormones.
Testosterone, produced primarily in the testes, has an anabolic effect in people, that is, it helps repair and rebuild muscle and bone tissue. In human medicine it’s often used to treat people with wasting diseases or recovering from surgeries. Synthetic forms of testosterone were developed to give people the benefits without the unwanted side effects, mainly the development of secondary male characteristics. Synthetic steroid hormones that have this anabolic effect are called anabolic steroids.
Abuse of anabolic steroids and substances that the body converts to steroids is most often associated with athletes trying to build muscle, strength and endurance, but their illegal use is also reported to be growing among teens wanting to buff up.
Beef producers don’t abuse the use of steroid hormones in beef production, as evidenced by a compliance rate greater than 99.9 per cent on residue tests. They achieve high compliance by choosing appropriate products for specific classes of cattle and using them according to manufacturers’ instructions.
The Canadian Food Inspection Agency (CFIA) conducts ongoing random spot checks at packing plants and has zero tolerance for hormone levels that exceed specified limits.
Use of growth promotants (hormones, ionophones and beta agonists) in beef cattle production isn’t anything new or covert. The products must be manufactured, tested and proven safe for beef cattle and beef consumers in accordance with Health Canada’s Food and Drugs Act regulations.
The Canadian Animal Health Institute reports that steroid hormones have a long safety record without incident for cattle and consumers dating back to their introduction in Canada in the 1960s and 1950s in the U.S. They are also approved for use in Mexico, Australia, New Zealand, South Africa, Japan, Chile and another 24 countries. The World Health Organization, United Nations Food and Agriculture Organization, the European Community Scientific Committee and the Joint Expert Committee on Food Additives agree that hormones used in beef cattle production don’t pose a health risk to humans.
Steroid hormones and beef cattle
Zeranol, which is the active ingredient in the name brand, Ralgro, isn’t a steroid, but acts like a steroid by binding to the estrogen receptor. It is a synthetic form of the natural estrogen, zearalenone, produced by Fusarium spp. fungi.
According to The Merck Veterinary Manual, natural testosterone isn’t used on its own in farm animals because of the difficulty in achieving effective blood concentration levels over a long period of time (100 days) with current delivery systems. The synthetic form, TBA, has greater anabolic activity, especially in feeder heifers and feeder cows and when combined with estradiol for steers.
Estradiol naturally occurs in relatively large quantities in male and female cattle and has potent anabolic effects at very low blood concentration levels in cattle. Supplementing estradiol is more effective in steers than for feeder heifers and feeder cows.
Most of the approved implants are combinations of estradiol with TBA and/or natural progesterone added because the latter two seem to have the effect of slowing down estradiol release. Zeranol is a stand-alone product.
The forms of estradiol, testosterone and progesterone in implants aren’t orally active. If eaten they would be broken down by digestive acids and enzymes in the liver before entering the bloodstream.
That’s why steroid users who abuse veterinary steroid hormones inject them rather than eat them, Bergen explains. Oral steroid hormones for people are alkylated so they bypass the liver and enter the bloodstream.
Implants for beef production are commercially available in compressed pellets or silastic rubber to be implanted under the skin of the outer ear, which is easily discarded during processing. Release of hormones from compressed pellets is rapid at first, then slows over the course of 120 to 200 days, depending on the product.
MGA is approved as a feed additive for feeder heifers, mainly to suppress reoccurring heat cycles and the associated riding activity, thus conserving energy for growth. It may also have the effect of increasing estradiol release from the follicles.
Bergen says a key point is that cattle are implanted long before they go to slaughter. By then, the implant hormone is used up. That’s partly why feed efficiency and growth rate trail off later in the feeding period — the implants and their growth-promoting effects are depleted.
It’s also why there’s almost no measurable difference in hormone levels in beef from implanted and unimplanted cattle. There is more variation in hormone levels between male and female cattle than between treated and untreated animals.
BCRC’s document, “Optimizing Feed Efficiency in Feedlots,” explains how and why beef producers may provide ionophores and beta agonists as feed supplements to improve feed efficiency and weight gain. Neither contain steroid hormones, nor do they mimic or supplement hormones, Bergen clarifies.
Ionophores are a class of antibiotics not used at all in human medicine. They improve feed efficiency in several ways, one of which is by inhibiting methane-producing bacteria in the rumen that waste feed nutrients because energy in the form of methane can’t be absorbed by the animal. The CFIA’s surveillance program ensures there are no antibiotic residues of any kind in beef.
People are most familiar with beta adrenergic agonists used in asthma medication. In cattle, beta adrenergic agonists bind to a beta receptor on the muscle and act sort of like adrenaline to redirect nutrients to muscle growth instead of fat buildup toward the end of the feeding period. Being water soluble, beta agonists approved for use in beef cattle in Canada don’t stay in the animals for more than a couple of hours. Compliance with use and withdrawal times is 99 per cent.
Bergen feels consumers are concerned about conventional beef production practices because they don’t understand them. BCRC’s blog post on conventional production of Canadian beef and other sound information can be found on its website, along with many useful references when talking with consumers about why the beef industry does what it does.
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