My Associate Editor and I had the following letter published on the web site of the Western Journal of Medicine.

It was written in response to a recent Op-Ed piece (West J Med 2001;175:7-9) concerning the use of IGF-1 (insulin-like growth factor-1) by athletes, who use it to enhance their performance. Unfortunately, levels of these growth hormone and insulin mimicking substance are elevated in our milk supply, due to the use of rBGH (also known as rBST) to increase the cow's milk production.

by Joseph Mercola, DO and Cory Mermer

Adams does an excellent job of discussing the dangers of the exogenous IGF-1, and properly cautions against its use, citing both lack of efficacy and potential adverse effects, such as disruption of the insulin system and carcinogenesis.

However, it is worth noting that much of the US population are unknowingly consuming higher levels of IGF-1 than previously and may face the same elevated risks, since it has been shown that milk from cow's treated with rBGH (Posilac) have significantly elevated IGF-1 levels. Measuring these levels has even been proposed as a basis by which to test for the use of rBGH (1).

In addition, the IGF-1 in the milk of rBGH treated cows is potentially more bioactive than the naturally occurring form and may be increased further by pasteurization (2).

While Adams notes the lack of significant effects of IGF-1 administration in elderly subjects, this certainly does not mean that this would be true for children, who may be at an increased risk of adverse effects.

Children's rapid growth rate may predispose them to be more susceptible to IGF-1. In addition, children's intestines, particularly infants, are naturally more permeable than adults, which could allow greater absorption of the large IGF-1 peptide.

While it has sometimes been assumed that IGF-1 can't be significantly absorbed when taken orally, several studies have demonstrated that this is not the case.

It was found that premature babies who were given breastmilk in addition to formula had almost double the serum IGF-1 levels of those receiving formula alone (3). This is not surprising, since breastmilk contains IGF-1 and formula does not, but it does strongly suggest intestinal absorption.

It was also demonstrated that people who consumed 3 servings of milk daily had a 10% higher serum IGF-1 level and almost a 10% lower level IGF Binding Protein 4 (IGBP-4) than those drinking less than 1-1/2 servings (4).

While IGF-1 may only be absorbed in limited quantities in healthy subjects, this is likely not be the case for those suffering from various conditions that can cause increased intestinal permeability, such as celiac disease, Crohn's disease, autism, cirrhosis, and cow's milk allergy, just to name a few.

In addition, the use of various medications, such as aspirin and other NSAIDs can increase intestinal permeability and it is estimated that 10% to 20% of the general "healthy" population suffers from this condition as well (5).

It is not enough to look at healthy adults and say that the intestinal absorption of IGF-1 is negligible. Rather, the most vulnerable in society need to be protected.

Adams eloquently points out that the use of IGF-1 for enhancing athletic performance "ignore(s) our understanding of the integrated nature of physiologic systems". However, this same ignorance was used when the FDA chose to approve rBGH.

Let's not put corporate profits ahead of children's health.

The use of growth hormones in livestock has certainly NOT been proven safe, and there are no overriding benefits that would justify such risks.

Western Journal of Medicine August 6, 2001 (web site only)

REFERENCES:

1. Daxenberger A, Breier BH, Sauerwein H. Increased milk levels of insulin-like growth factor 1 (IGF-1) for the identification of bovine somatotropin (bST) treated cows. Analyst 1998 Dec;123:2429-35.

2. Epstein SS. Unlabeled milk from cows treated with biosynthetic growth hormones: a case of regulatory abdication. Int J Health Serv 1996;26:173-85.

3. Diaz-Gomez NM, Domenech E, Barroso F. Breast-feeding and growth factors in preterm newborn infants. J Pediatr Gastroenterol Nutr 1997 Mar;24:322-7.

4. Heaney RP, McCarron DA, Dawson-Hughes B, Oparil S, Berga SL, Stern JS, Barr SI, Rosen CJ. Dietary changes favorably affect bone remodeling in older adults. J Am Diet Assoc 1999 Oct;99:1228-33.

5. Hollander D. Intestinal permeability, leaky gut, and intestinal disorders. Curr Gastroenterol Rep 1999 Oct;1:410-6.

COMMENT FROM ANDREAS SCHULD:

IGF-1 is released from the liver in response to growth hormones such as bGH, etc. They act co-dependently with thyroid hormones on many bio-chemical activities, especially with TSH, the thyroid-stimulating-hormone. Fluoride mimics the activity of TSH in the system.

Fluoride also increases IGF-1 levels:

Turner CH, Garetto LP, Dunipace AJ, Zhang W, Wilson ME, Grynpas MD, Chachra D, McClintock R, Peacock M, Stookey GK - "Fluoride treatment increased serum IGF-1, bone turnover, and bone mass, but not bone strength, in rabbits" Calcif Tissue Int 61(1):77-83 (1997)

"IGF-1 was increased by fluoride and was associated with increased bone turnover, but was not correlated with bone formation markers. High-dose fluoride treatment did not improve, but decreased, bone strength in rabbits, even in the absence of impaired mineralization."

AMD may act additively with IGF-1:

Veldman CM, Schmid C - "Differential effects of fluoride and insulin-like growth factor I on sodium-dependent alanine and phosphate transport in a human osteoblast-like cell line" Growth Horm IGF Res 8(1):55-63 (1998)

"The effects of fluoride and IGF-I were additive..."

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