Hormones in meat image So what’s this debate all about? Why do some people suspect hormonal additives are unhealthy? Are their suspicions founded? Here’s the science behind the scare.

The Culprits: Hormone Additives

Hormones are powerful, naturally produced chemical messengers that control vital behaviors in all plants and animals. Ergo, they are present in all animal products whether or not the animals have been treated with hormone supplements.

Hormones Used in Livestock

Certain steroid hormones are currently approved for use in US livestock to speed lean muscle growth. Both the Food and Drug Administration (FDA) and a joint committee of the Food and Agricultural Organization and World Health Organization (FAO/WHO) deemed residues of these additives in meat safe for consumption. Three of the approved additives are steroid hormones that occur naturally in both cows and humans, and the other three are synthetic variations of growth hormones.

Hormones Used in Dairy Cattle

In 1993, the FDA and a National Institutes of Health (NIH) panel of experts approved the use of recombinant (eg, genetically engineered) bovine growth hormone (rbGH). This protein hormone promotes increased milk production as opposed to muscle growth. Its approval came only after extensive review of available data that showed the milk of treated dairy cattle to be safe.

Dairy cattle that receive rbGH produce at least 10% more milk than other cows. As opposed to cattle raised as livestock, no steroid hormones are approved for use in dairy cattle.

Suspected Health Concerns

Too much or little of any hormone can be harmful to the body, and in severe cases can result in an endocrine disorder such as diabetes or hypothyroidism. Additionally, certain cancers are known to be responsive to some hormones in the steroid class. Estrogen is listed as a known carcinogen (most associated with uterine cancer, followed by breast cancer), and progesterone as “reasonably anticipated to be” a carcinogen, in an updated report by the National Toxicology Program at the Department of Health and Human Services.

Concerns Over Additives in Beef

While taking steroid hormones at high doses, such as in hormonal replacement therapy, has been shown to increase risk for some cancers, the amount present in meat products is very small by comparison. The FDA argues that residues of additives in beef are negligible in comparison to levels that occur naturally both in cows and humans.

Authorities also point out that steroid hormone levels in beef, whether from treated animals or not, are far lower than those found in eggs or milk. Additionally, these levels are dwarfed by high levels of plant estrogens—or “phytoestrogens”—present in soybeans, wheat germ, cabbage, broccoli, and many other vegetables. Phytoestrogens have also been shown to be hormonally active in people.

One lesson from history may explain the continued wariness toward hormonal additives. The synthetic estrogen hormone, diethylstilbestrol (DES), that was used beginning in the 1950s to fatten cattle and chickens, as well as to prevent miscarriages in women, was found to increase cancer risk in humans. Its use in food production was phased out by 1979, several years after it was pronounced to be a known carcinogen. The DES misfortune peaked awareness of the potential dangers of chemical additives in both food and drugs.

Concerns Over Additives in Dairy

As for dairy hormones, critics of rbGH, such as the Consumer Union and the Cancer Prevention Coalition, argue that milk from treated cows contains higher levels of this hormone than milk from non-treated cows. However, rbGH is not recognized as a hormone in the human body, and even if it were, as a protein hormone it is broken down into metabolites in the stomach (unlike steroid hormones, which do pass into the bloodstream when ingested orally), so any health risk is biologically unlikely.

More importantly, critics contend that the milk also contains higher levels of insulin-like growth factor-1 (IGF-1), a protein hormone that is identical in cows and humans. IGF-1 plays an important role in milk production, bone growth, and cell division. However, after review of multiple studies by the FDA, they determined that the levels were similar in milk from treated cows and untreated cows. And while IGF-1 is naturally present in humans, research suggests that elevated levels are associated with breast, colon, and prostate cancers. The Harvard-based Nurses’ Health Study found higher blood levels of IGF-1 in women with breast cancer than in those without. Still, no research has been done to show if drinking milk with higher levels of IGF-1 translates to higher blood levels of IGF-1.

An Undetermined Verdict

For now, no conclusive evidence exists either to support or totally refute the purported health risks from consuming meat or dairy from hormonally treated cows. Studies that compare long-term morbidity between people who consume products of treated cattle and people who do not will be essential to closing the debate on their questionable healthfulness.

Until more rigorous research is done, some might prefer to err on the side of caution. Among authorities that do advise caution, most say that pre-pubescent children are at greatest risk. Pregnant women may also want to use caution. Here are some tips if you want to keep treated products off your or your family members’ plate:

  • Buy certified organic meat and meat products: Organic animals can only be fed 100% organic feed and cannot be given antibiotics or growth hormones. It is also safe to buy imported European meat products, as added growth hormones are banned in the EU.
  • Buy rBGH-free or certified organic milk and dairy products: Organic dairy farms do not allow the use of rBGH, and other companies that do not use rBGH often include this information on the label. It is also safe to buy imported European and Canadian cheeses and other dairy products, as rbGH is banned in these countries.