Chamomile tea has been seen as a medicinal cure-all for centuries, but only now have UK researchers found evidence that the herbal tea has real benefits in a wide range of health ailments from the common cold to menstrual cramps. Elaine Holmes of Imperial College London and her colleagues described their findings in the January 26 issue of the Journal of Agricultural and Food Chemistry.

Holmes and her colleagues studied the German chamomile (Matricaria recutita), also known as manzanilla. Chamomile flowers and leaves are brewed to make a fragrant, flavorful tea. The researchers gave seven female and seven male volunteers five cups of the herbal infusion to drink each day for two consecutive weeks and tested their urine before and after imbibing the tea.

The researchers found that drinking chamomile tea significantly raised urinary levels of hippurate, one of the gut microbial breakdown products of plant-derived phenolics and other phenolic compounds. They suggest that the change in the activity of the gut microflora could help explain the association of the drink with a boost to the immune system. "Gut microflora are known to play a role in the immune system," Holmes told Reactive Reports, hence the connection, "The chamomile alters the original microflora in the intestine, which changes the levels of chemicals excreted in urine and available for re-absorption."

The researchers found that the metabolite profiles had not returned to baseline two weeks after the volunteers stopped drinking the tea, which implies that the tea had a prolonged or perhaps irreversible effect. Holmes adds that, as is often the case with probiotics and other preparations, the intervention changed the gut microflora. "Nobody has definitive proof of whether this is a benefit or risk in the long term," Holmes explains, "The findings highlight the need for further studies into the longer term effects of nutritional intervention on human metabolism."

Natural products and functional foods are not necessarily controlled by the FDA and other regulatory agencies and the regulations are not as strict as they are for pharmaceutical and other medical products.

Drinking chamomile tea also raised urinary levels of the amino acid glycine, which has been demonstrated to reduce muscle spasms. Glycine is sold in dietary supplement form as a muscle relaxant. This could explain the benefits of chamomile tea in relieving menstrual cramps in women, probably by relaxing the uterus. Glycine is also known to act as a nerve relaxant, which the researchers say may explain why the tea seems to act as a mild sedative.

Chamomile tea

The team found that hippurate and glycine levels remained elevated for up to two weeks after the volunteers stopped drinking chamomile tea, indicating that the compounds may remain active for quite some time. "Hippurate is conjugated from benzoic acid and glycine and this is performed by the microflora," explains Holmes. Additional studies are needed before a more definitive link between the tea and its purported health benefits can be established. The study also demonstrated that metabonomic methods could be useful as a generic means of profiling the effects of natural products on humans.

Holmes said that this is just one of a growing number of studies showing how commonly used "natural products" may contain chemicals of medicinal value. "The healthcare industry is placing increasing emphasis on functional foods including natural remedies," she added, "yet little work has been conducted on the long term effects of such products on human biology." Numerous research teams around the globe are hoping to remedy that situation.

J Agric Food Chem, 2005, 53, 191-196; http://dx.doi.org/10.1021/jf0403282

http://www1.imperial.ac.uk/medicine/research/depts/