An in-office evaluation of four dietary supplements on natural killer cell activity

Townsend Letter for Doctors and Patients, Feb-March, 2005 by James Belanger

Shortcomings of this study were as follows: Sample size was small in each group, but represented 29 cancer patients with abnormally low NK cell activities (<20 lytic units) who needed a reliable product to help them. Many patients were taking other nutritional supplements and/or chemotherapy on the same days as the test products. It is possible that these other substances could have interfered with the results. In the clinical world, however, cancer patients are rarely on one medication or nutritional supplement. Because of the complexities of cancer, it is most effectively treated with combination therapy that addresses growth factors, angiogenesis and cellular replication as well as the immune system. A good NK cell activator needs to be able to work even in the midst of other therapies. The only product that consistently increased NK cell activity despite the use of multiple nutritional supplements and concurrent chemotherapy was AHCC.

The dose of antigen-infused dialyzable bovine colostrum/whey extract used in this study was lower than the 600-800mg/day recommended by Stoff. (32) Some manufacturers of this product, however, recommend 100mg/day of antigen-infused dialyzable bovine colostrum/whey extract in conjunction with astragalus, maitake and arabinogalactan, which will support healthy natural killer cell levels. The dose used in this study, therefore, was chosen to lie in between these two recommendations.

NK cell activity can be affected by a variety of factors including depression, lack of social support, (41) high fat diets (>20% of total calories, including unsaturated fats), (42) age and exercise levels. (43) Patients in this study, however, kept their diet and exercise routines consistent. Everyone also had a good support system and did not suffer from major depression.

Critics may say that the NK cell activity is not reliable because it frequently fluctuates. This statement, to the author's knowledge, has not been verified by any published clinical studies. In fact, many studies show that the standard 4-hr [.sup.51]Cr-release assay is very accurate as long it is done properly and the data is expressed appropriately. (44) Critics may also say that the activities of NK cells in an assay are different from their activities in the human body. Numerous clinical studies, however, show there is a relationship between the 4-hr [.sup.51]Cr-release NK cell assay and prognosis, tumor burden and risk of metastasis in cancer patients. (3-22)

Three other products touted as NK cell activators, inositol hexaphosphate with inositol, maitake extract and larch arabinogalactan, were not used in this study for the following reason. Other patients not included in this study were taking these products consistently for several months before baseline NK cell activities were done. These patients happened to have extremely low NK cell activities at baseline despite taking the suggested doses of inositol hexaphosphate with inositol, maitake extract or larch arabinogalactan for several months.

Conclusion

Despite today's advances in oncology, many people with early stage cancers are dying in less than five years. Clearly, advances need to be made in cancer therapeutics. Activating natural killer cells with an oral agent may be one therapy that can improve these survival rates. (28-30, 40, 45) This study found only AHCC to be a consistent natural killer cell activator even when combined with chemotherapy and other nutritional supplements. More studies, however, need to be done to see if AHCC is effective at decreasing recurrence rates and increasing survival rates in early stage cancer patients in remission. The author knows of only one study so far looking at AHCC and prognosis that has been published. This study found that AHCC improved survival rates in postoperative hepatocellular carcinoma patients. This study, however, was not randomized and therefore, results may have been influenced by self-selection bias. (45) Krestin is also another product that shows a lot of promise. Follow-up immune system testing, however, should be done if one is using Krestin or another coriolus product.