Tuesday, April 14, 2009

Adverse effects of horomones found in cow milk

The following isw an excerpt form Dr. Cordain's PaleoDiet news letter.

Insulin
Type 1 diabetes (T1D) is an autoimmune disease in which immune cells (T-lymphocytes) mount an attack on the cells of the pancreas that produces insulin (beta cells) resulting in its destruction. These patients have to rely on insulin replacement therapy to live. Last week, we discovered that bovine insulin (BI) is present in commercially pasteurized milk and infant formulas. We also learned that BI has good oral bioavailability since antibodies to BI are a common phenomenon among children who have consumed infant formula containing cow's milk. This is very important information for children who have a genetic predisposition for T1D because BI differs from human insulin by only three amino acids. The immune response induced by BI in these children may react with human insulin and lead to β-cell destruction, especially if children are exposed to infant formula containing cow's milk before the age of 3 months. This is a period of high intestinal permeability or leaky gut. As expected, various epidemiological studies have associated cow's milk consumption with T1D in genetically susceptible children, especially when the initial exposure begins in the first months of life. Thus, exclusively breastfeeding during the first 6 months and avoiding formulas based on cow's milk is highly recommended.

IGF - 1
We already know that cow's milk is associated with increased plasma IGF-1 concentrations in both children and adults. Furthermore, there is evidence that cow's milk increases the IGF-1/IGFBP-3 ratio, setting a hormonal cascade that may ultimately result in epithelial cell cancers and acne, among other diseases.

Betacellulin
Humans have a hormonal receptor called the epidermal growth factor (EGF) receptor (in the skin, gastrointestinal tract, lung, kidney, mammary gland, pancreas, prostate gland, ovary and other tissues) that binds the EGF family of hormones, including Betacellulin (BTC). BTC is a hormone found not only in liquid cow's milk, but also in whey and cheese. Why is this relevant? There is a very good probability that BTC may survive degradation by gut enzymes, bind the luminally expressed EGF receptor in the gut, and thereby enter circulation. If this chain of events occurs, then BTC may also bind the EGF receptor bound in all epithelial cells. This is where it might contribute to the pathogenesis of epithelial cell cancers and acne since up-regulation of the EGF receptor pathway occurs in acne31 and in a wide variety of cancers including breast, prostate, ovarian, lung, pancreatic, gallbladder, stomach, testicular, kidney, and head and neck cancers.

Estrogens

Various milks contain estrogen metabolites and that the most prevalent form of estrogen in cow's milk is estrone sulphate, which has high oral bioactivity. This is potentially alarming for the following reasons:
In vitro and animal studies support the notion that estrogens are implicated in prostate cancer.
Estrogens may adversely effect the ovarian epithelium.
The use of hormone replacement therapy (HRT) is associated with an increased incidence of corpus uteri cancer in the United States, and it should be remembered that estrone sulphate comprises 45% of the conjugated estrogens in Premarin and Prempro. These are the most frequently prescribed hormone replacement therapies for menopausal women.
Estrogens can initiate breast cancer and promote the growth of existing tumors in breast tissue.
Elevated plasma concentrations of endogenous estrogens are associated with increased risk of breast cancer.
Exposure to estrogens through HRT and oral contraceptives is associated with an increased breast cancer risk.
Whole and low fat milk were found to promote 7,12-dimethylbenz(a) anthracene induced mammary tumors in rats.
Dihydrotestosterone (DHT) precursors As mentioned last week, commercially pasteurized cow's milk contains progesterone, 5α-androstanedione and 5α-pregnanedione that are dihydrotestosterone (DHT) precursors, and DHT is implicated in acne and prostate cancer.

Unfortunately, we aren't aware of any study that has looked at the absorption of these hormones, so we don't know if this is really a problem. Nevertheless, evidence that other hormones have good oral bioavailability suggests that it may indeed be a cause for concern. As expected from the evidence presented, dairy intake is strongly associated with a higher incidence of acne, moderately associated with prostate cancer, and mildly associated with ovarian cancer. Dairy consumption has also been associated with an increased incidence of testicular, kidney, and head and neck cancers. There have been very few studies looking at this, so it is difficult to draw more significant conclusions. Although epidemiological evidence can't show cause and effect, and clearly, many more studies need to be conducted, the current evidence strongly suggests that cow's milk may be implicated in a variety of cancers as well as acne.

The Paleo Diet, by emulating the nutritional characteristics of hunter-gatherer diets, avoids the consumption of milk and other dairy products. Thus, the Paleo Diet protects us from the potential problems inherent in dairy consumption. Yet, when combined with sufficient sun exposure and proper exercise, the Paleo Diet still optimises bone health because it:
1. Provides all the micronutrients (including calcium, which can be obtained from green leafy vegetables, such as broccoli and kale) needed to optimize bone health and prevent osteoporosis
2. Includes enough fruits and vegetables to be net base yielding (a net acid yielding diet can cause calcium and magnesium losses
3. Includes sufficient protein (which increases intestinal calcium absorption and has an anabolic effect on bone, particularly in the context of a net base yielding diet
4. Has a lower omega 3/omega 6 ratio (a diet with a high omega 6/ omega 3 ratio can cause bone loss and a low glycemic load/insulinotropic effect (high insulinemia causes calcium loss)

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