Hormones and Growth Factors in Raw Milk

Beer has hormonal activity

Many people are concerned about the presence of hormones in milk and other foods, and rightfully so. Hormones and growth factors (such as IGF-1, insulin-like growth factor-1) are powerful substances with far-ranging effects on virtually all of the body's tissues. When making food choices for yourself and your family, it's important to be aware that many products contain a natural complement of hormones, and always have. Processed foods, especially pasteurized milk from cows dosed with artificial hormones like rBGH, have altered ingredient levels which may be responsible for unwanted health effects.

Rest assured, with regard to hormones, clean raw milk from organic grass-fed cows contains only the precisely balanced trace amounts that nature puts there. To understand this important class of substances, (we tend to fear things we don't understand) we'll need to learn more about hormones themselves, how they work, and how they can impact our health in positive or negative ways.

In simple terms, all hormones are basically chemical messengers with various life-spans, which get released from one tissue or another, are transported via the bloodstream or intracellular fluid, and end up at target cells in the same region or different tissues entirely. In our bodies, the various glands of the endocrine, and other systems, secrete hormones that carry messages to speed up, slow down, turn on and off, increase, decrease, raise, lower and alter in countless other ways, the complex array of organs and systems that make up who we are.

Hormones, and compounds that behave like them in our bodies, are all around us. All animal products and a good many plants contain 'bioactive' substances- compounds that can affect our bodies either positively or negatively by locking into receptors normally reserved for our body's own hormones. Some of these powerful substances come at us from unexpected directions- for instance, a substance in ever-present and annoying diesel fumes has been shown to have hormonal activity in humans.

Endocrinologists (scientists who study hormones) tend to lump them into four structural groups, based mainly on their composition. It's fairly common for members from each group to have several properties in common with one another, which shows that their receptors are not as finicky as they could be. A good example of this is the growing number of chemicals in our environment that have been discovered to act like the hormone estrogen in our bodies (estrogen mimics), like phthalates, which leach from plastics. By the way, men, I regret to have to tell you that the bitter hops in beer (above) contains a potent estrogen mimic (8-prenylnaringenin)...

Peptide/Protein hormones, like insulin, are made from chains of amino acids (think beads on a string) called, peptides. Very long strands of peptides with complex bends and folds, more familiar to us as proteins, also exhibit hormonal activity. Usually they're assembled in the scary-sounding storage/synthesis regions of the cell called the endoplasmic reticulum (ER).

Cortisol molecule

Steroid hormones, such as the sex hormone testosterone and the stress hormone cortisol (right), are fat-like lipids manufactured in a back and forth shuttle between the tiny power plants of our cells (mitochondria) and the above mentioned ER. There, with the help of a bevy of enzymes, the hormone precursor or building block for all the steroid hormones, pregnenolone, is fashioned out of cholesterol molecules. Still other enzymes then customize the pregnenolone into the particular steroid hormone needed at that moment.

A number of other familiar hormones fall into the category known as Amino Acid Derivatives. Amino acids, remember, are the individual 'beads' that make up peptides and proteins. Tryptophan, of sleep-inducing warm milk and turkey dinner fame, is the precursor to the pineal gland hormone melatonin (and the depression-busting neurotransmitter, serotonin). The important thyroid hormone, thyroxine, and neurotransmitter/hormone epinephrine both get their start from molecules of the amino acid tyrosine.

The Eicosanoids, or Fatty Acid Derivative hormones get their start, as the name implies, from fatty acids, the chains of carbon and hydrogen atoms which form the bulk of fat (triglyceride) molecules. One of the better known groups of this class, the prostaglandins, figures heavily in the body's inflammatory response. People with asthma and arthritis are all too familiar with these powerful substances.

Many hormones, especially the eicosanoids, are short-lived, staying active for only a few seconds. Others, in the protective folds of large protein molecules, last for hours. The steroids typically exhibit effects until either deactivation by metabolic changes in their molecules or by excretion in the waste, which can be a few days. This very transitory nature of hormones makes testing for content levels in milk tricky at best. The bulk of the studies I came across showed quite a bit of variation both in amount and just which hormones were present in the samples tested.

Other major factors contributing to uncertainty in hormone content/concentration include the breed of cow, time of year, stage of the lactation cycle and what the cow was fed. The composition of milk very definitely reflects the diet from which it is produced. High-percentage grain diets and production-enhancing hormone injections increase the volume of milk produced, but dilute overall levels of nutrients and can skew growth factor content upward. Since none of the studies mentioned the diet composition of the cows whose milk they examined, the variation in results came as no surprise.

Delving into the world of hormones can be a lot like wading in alphabet soup. Take a deep breath and jump in anyway! Leaving this section with even a rudimentary understanding of the amazing hormonal system of checks and balances (called 'feedback loops') in clean raw milk will help allay any concerns you may have that this food can negatively impact your health. Hopefully, as you read, you'll discover, as I did, what an amazingly complex tapestry the bioactive components of raw milk actually weave.

While I can't verify the presence, concentration or activity of each substance on the following list, it's indisputable that nature's genetically controlled concentrations of promoters and inhibitors in organic raw milk, left to their own devices, assure that key nutrients are carried to where they're needed, unwanted excesses are suppressed and that growth and maintenance are the order of the day.


(Just a few words about the units of measurement used here- a gram [g] is pretty light- there are 28.35g to an ounce. A microgram [mcg] is one millionth of a gram. A nanogram [ng] is one billionth of a gram. A picogram [pg] is one trillionth of a gram- only a little bit more than none at all. A mililiter [ml] is one thousandth of a liter and there are just under 30ml to the fluid ounce.)

Adrenocorticotropic Hormone (ACTH): A 39 amino acid polypeptide hormone that acts in the cortex of the adrenal gland to increase production of corticosteroid hormones, two groups in particular- the glucocorticoids and the mineralocorticoids. The glucocorticoids, such as cortisol, control stress response, protein, carbohydrate and fat metabolism, and have anti-inflammatory properties as well. The mineralocorticoids, like the hormone aldosterone, control water and electrolyte levels in the body by inducing the kidneys to retain sodium. ACTH has a very short half-life of 10 minutes. The term half-life refers to the amount of time it takes 50% of a substance to degrade or lose activity. In the case of ACTH, every 10 minutes, another 50% of what's left degrades until it's completely gone.

Bombesin (Gastrin Releasing Peptide- GRP): A 13 amino acid neuropeptide that works with gastrointestinal tract neuroendocrine hormone (GTNH) to induce gastrin release. It also teams up with cholecystokinin (CCK) to signal satisfaction from hunger (satiety).

Bovine Growth Hormone (BGH): A protein hormone secreted by the cow's pituitary that regulates growth and development of the animal. Due to similarities in receptors for the milk production (lactation) hormone prolactin (PRL), BGH can also induce lactation. BGH also stimulates secretion of insulin-like growth factor-1. Due to differences in molecular shape, BGH is believed not active in humans. BGH: < 1 ng/ml

Calcitonin: A 32 amino acid polypeptide hormone that aids in proper calcium and phosphorus metabolism, prevents hypercalcemia (elevated calcium levels) after meals, and reduces blood calcium levels by regulating calcium ion absorption in the intestines, lowering osteoclast (bone absorbing cell) activity and decreasing kidney tubule calcium and phosphate reabsorption rates. It also enhances mineralization of skeletal bone and helps reduce bone calcium loss during pregnancy and lactation. As if that weren't enough, calcitonin also regulates Vitamin D, and, along with CCK and GRP (bombesin), helps to signal satiety. Its actions are offset by PTH, which increases blood calcium levels.

Cholecystokinin (CCK): A peptide hormone with forms containing either 8, 33 or 58 amino acids that stimulates digestion of fats and proteins by triggering the pancreas to secrete the digestive enzymes lipase, amylase, trypsin and chymotrypsin, and by stimulating contraction of the gall bladder to release fat-emulsifying bile into the small intestine. It works with bombesin, and calcitonin to mediate feelings of satisfaction after eating.

Epidermal Growth Factor (EGF): A 53 amino acid protein that stimulates growth and repair of tissues in the gastrointestinal tract, especially keratinocytes (a special type of skin cell) and fibroblasts (cells that form structural fibers in collagen and other connective tissues).

Erythropoietin (EPO): A 165 amino acid glycoprotein hormone (glycoproteins consist of several sugar molecules linked with a protein molecule). EPO stimulates erythrocyte (red blood cell) production in the bone marrow, boosting the blood's ability to carry oxygen. Studies have shown that significant amounts of EPO resist digestion and survive to reach receptors in the intestinal tract. One raw milk-drinking athlete was wrongly accused of blood-doping, so there's at least anecdotal evidence of EPO's activity in our systems!

The Estrogens: An important and often controversial class of steroid sex hormones including estradiol and estrone, usually associated with females, but present, and with important functions in males as well. Aside from their obvious influence on breast and uterine development, the estrogens (which are actually derived from the male sex hormones or 'androgens' testosterone and androstendione) bolster bone maturation, strength and density, regulate formation of sperm cells and play crucial roles in fat (lipid), circulatory, respiratory and nervous system metabolism. The trace amounts present in bovine milk are considered too low to exhibit any physiological activity. Progesterone, also present in raw milk, has an inhibitory effect on the estrogens. Estradiol: 160 pg/ml, Estrone: 34-55 pg/ml

Follicle Stimulating Hormone (FSH): A 210 amino acid glycoprotein hormone which promotes the maturation of immature ovarian follicles. In men, FSH facilitates production of proteins crucial to formation of sperm cells. The half-life of FSH is 3-4 hours, so unless you're drinking straight from the cow, chances are there'll be little, if any, active hormone left by the time your raw milk makes it to the refrigerator.

Gastrin: A peptide hormone with forms containing 14, 17 or 34 amino acids. Gastrin functions to stimulate parietal cells in the stomach to secrete hydrochloric acid. It causes other cells to secrete pepsinogen, (an inactive form of the digestive enzyme pepsin) that converts to pepsin in a low pH (acidic) environment. It also stimulates production of pancreatic enzymes. Gastrin secretion is regulated by gastrin releasing hormone (GRH) and gastrin inhibitory peptide (GIP), both of which are also found in raw milk.

Gonadotropin Releasing Hormone (GnRH1): A 10 amino acid peptide hormone that triggers the release of follicle stimulating hormone (FSH) and Luteinizing Hormone (LH) from the anterior pituitary gland. GnRH1 is degraded by proteolysis (digestion of proteins by cellular enzymes called proteases) within a few minutes of secretion. GnRH1: 0.1-3 ng/ml

Growth Hormone Releasing Hormone (GHRH): A 44 amino acid peptide hormone that stimulates secretion of growth hormone (GH) from the anterior pituitary gland. GHRH also helps promote slow wave or Stage 3 and 4 sleep. It's action is opposed by somatostatin, also present in raw milk.

Insulin: Well-known polypeptide hormone that, among a multitude of other functions, chiefly regulates carbohydrate and fat metabolism. Bovine insulin differs from the human form by only three amino acids and appears to share a similar level of activity. Insulin: 4-6 ng/ml

Insulin-like Growth Factor-1 (IGF-1): A protein hormone with a structure similar to insulin, produced in response to growth hormone (GH). It regulates growth and development in just about every cell in the body. Abnormally low levels are considered diagnostic for growth hormone deficiency. Most IGF-1 is carried by binding proteins that can prolong its half-life (to about 6 hours) but reduce its activity. Free (unbound) IGF-1has a half-life of about 10 minutes. IGF-1: 1-10 ng/ml

Luteinizing Hormone (LH): A 23 amino acid glycoprotein that triggers production of steroid sex hormones in both males and females. In men, certain cells in the testes react to LH by producing testosterone which, by the way, is a precursor for the female sex hormones. In women, LH induces cells in the ovaries to form estrogens, such as estradiol, estriol and estrone. LH has a half-life of only 20 minutes, which virtually assures little, if any, will be left in your raw milk by the time you get it home.

Mammary-derived Growth Inhibitor (MDGI): A polypeptide found in milk fat globule membranes that has been shown to inhibit proliferation in several types of mammary epithelial (barrier) cells.

Nerve Growth Factor (NGF): A protein that stimulates growth and maintenance of neurons (nerve cells) and glial (non-nerve support) cells in the central (brain/spine) and peripheral nervous systems.

Neurotensin (NT): A 13 amino acid peptide that acts as both a neurotransmitter and hormone. NT has powerful analgesic (pain-relieving) and anti-inflammatory properties, various regulatory roles in the gastro-intestinal tract, and controls the release of numerous other hormones including somatotropin (SS), luteinizing hormone (LH) and prolactin (PRL). Neurotensin has a very short half-life.

Parathyroid Hormone (PTH): An 84 amino acid peptide hormone that raises calcium levels in the blood. It does this by fostering growth of osteoclasts, a type of cell which breaks down bone, by causing the kidneys to reabsorb calcium and by boosting intestinal calcium absorption through increased production of vitamin D. The hormone calcitonin offsets PTH activity by lowering blood calcium levels.

Parathyroid Hormone-related Peptide (PTHrP): A protein hormone similar to PH and necessary for proper eruption of the teeth. PTHrP also regulates cerebral blood flow and helps lower blood calcium levels by increasing osteoclast (bone absorbing) cell formation. PTHrP: 58-185 ng/ml

Progesterone: A multi-functional steroid hormone that belongs to a group called the progestagens- hormones that counteract the effects of estrogens on the body and that inhibit the production of sex steroids. It functions mainly in regulation of the menstrual cycle, gestation and embryonic development. Progesterone also has a number of important roles beyond the reproductive tract, including reduction of inflammation and immune response, assistance with thyroid activity and bone construction, reduction of gall bladder activity and raising of the core body temperature (thermogenesis). It's blockage of estrogen may help with inhibition of breast and endometrial cancers. Unfortunately, progesterone is poorly absorbed orally. Progesterone: 18-23 ng/ml

Prolactin (PRL): A 199 amino acid peptide hormone with numerous functions, the main being stimulus of mammary gland milk production. PRL-inhibiting factor and PRL-releasing factor, also present in raw milk, govern PRL secretion and expression. PRL: 6-8 ng/ml

Somatostatin (SS): A 42 amino acid peptide hormone that inhibits release of growth hormone (GH) by opposing the effects of growth hormone releasing hormone (GHRH). It also inhibits release of thyroid stimulating hormone (TSH) and suppresses or inhibits numerous gastrointestinal bioactives, including gastrin, CCK and vasoactive intestinal peptide (VIP). It also slows the rate at which the stomach empties, and thus enhances digestion.

Testosterone: A familiar steroid hormone typically associated with male sex traits, but present in females as well, in much lower concentrations. Classed as an androgen, testosterone controls the development of numerous masculine characteristics (including deepening of the voice in both sexes), but is also converted to the estrogen hormone, estradiol, which speeds up the conversion of cartilage into bone during periods of rapid growth. Testosterone: 40-75 pg/ml

Thyroid Stimulating Hormone (TSH): A pituitary hormone that triggers release of thyroxine (T4) and tiriodothyronine (T3) from the thyroid gland, both of which play key roles in determining the body's metabolic rate and temperature, rate of protein synthesis and sensitivity to a class of substances called catecholaminesthe best known example being the neurotransmitter/hormone epinephrine or adrenalin. TSH is inhibited by somatostatin.

Thyrotropin Releasing Hormone (TRH): A three amino acid tripeptide that induces the anterior pituitary gland to release thyroid stimulating hormone (TSH) and prolactin (PRL). TRH: 16-34 ng/ml

Transforming Growth Factor-Beta-1 (TGFB1): A polypeptide growth factor which regulates cell differentiation and proliferation. TGFB1 has been shown to inhibit the growth of epithelial cells. Bone morphogenetic proteins (BMPs), other growth factors in the TGFB1 family and possibly present in raw milk, cause the formation of new bone and cartilage.

Vasoactive Intestinal Peptide (VIP): A 28 amino acid peptide hormone that stimulates secretion of water and electrolytes, dilates (widens or expands) intestinal smooth muscle and peripheral blood vessels, and inhibits gastrin. It also stimulates gastric acid secretion. VIP has a 2 minute half-life in the blood.

That ought to suffice for now. As you can see, there's a lot more to raw milk than meets the eye. Bear in mind, this survey of its bioactives and their interactions is far from complete, and, undoubtedly, there are many more yet to be discovered.

The ingredient list for a food as powerfully healing and restorative as this is bound to be complex- and while the hormones and growth factors above certainly add to that complexity (and controversy), this amazing fluid has withstood the test of time. Organic raw milk has been, and continues to be, a food you can use to achieve and maintain good health- both for yourself, and for your family.