Thymus Extract

The thymus gland is found behind the sternum in the middle of the chest. Most active in unborn and very young children, it plays a significant role in the immune system. The theory behind the use of thymus extracts is that they might stimulate or normalize immunity. However, there is no real evidence as yet that any thymus extracts are effective, and they may present real health risks.

Thymus extract is produced primarily from the thymus gland of cows. This has led to concerns regarding mad cow disease. (See Safety Issues below.) Some studies have used chemically synthesized versions of chemicals found in thymus extract.

The dosage of thymus extract used in studies has varied widely, depending on the particular thymus product used.

A 1-year double-blind placebo-controlled trial of 16 children with frequent respiratory infections found that treatment with thymus extract could reduce the rate of infection. Intensive athletic training can suppress immune function and lead to colds as well. However, a double-blind placebo-controlled trial of 60 athletes failed to find any significant evidence of benefit with thymus extract. Highly preliminary evidence suggests that thymus extracts may be helpful for food allergies and asthma; it may do so not by boosting the immune system, but by calming it down and causing it to behave more normally. Thymus extract has been tried as a treatment for hepatitis B and C. However, the results of small double-blind trials have not been positive. Injectable forms of whole thymus extract or chemicals contained in it have been studied as a treatment for numerous conditions, including cancer, cold sores, dermatomyositis, eczema, genital warts, hepatitis, HIV infection, leukopenia (low white cell count), multiple sclerosis, psoriasis, respiratory infections, rheumatoid arthritis, scleroderma, and shingles (herpes zoster). The results of these studies have been mixed. In any case, the results of trials involving injected thymus cannot be considered applicable to oral thymus products.

Thymus extracts have not been definitely associated with any side effects. However, there are real concerns that any glandular extract might contain the virus causing mad cow disease. Keep in mind that there is no governmental regulation of thymus products sold as dietary supplements in the United States. Even when a ban is placed on importation of cow glands from a country where mad cow disease has been found, the ban does not apply to dietary supplements! For this reason, we recommend that you do not use thymus products sold as dietary supplements.