St John’s Wort makes fat cells resistant to insulin

From Ergo Log

It’s perhaps not a good idea for people with diabetes type-2 to use Saint John’s Wort, but for healthy athletes looking to reduce fat Saint John’s Wort may be an interesting supplement. We reached this conclusion after reading about a test tube study that biochemists at Louisiana State University did, the results of which will soon be published in Biochemical and Biophysical Research Communications.

Saint John’s Wort is best known as a herb that works well against mild depression, but regular readers of Ergo-Log will also know that the plant has other interesting properties too. In studies St John’s Wort increases the production of growth hormone, [Neuropsychobiology. 2004;49(2):58-63.] reduces the production of prolactin and speeds up the breakdown of estradiol. An important component of St John’s Wort is probably hyperforin.

Because Saint John’s Wort is a popular supplement and because increasing numbers of people are fighting obesity, the researchers thought it would be a good idea to study the effect of the plant on fat cells. They exposed fat cells of mice to extracts of the roots, leaves and flowers of the plant and measured how much glucose the fat cells were then capable of absorbing. The tests resulted in the figure shown below.

The graph shows the effect of extracts of the flowers of Saint John’s Wort. These are also found in supplements. Root extracts of the plant had little effect. Extracts from the leaves, which are also found in supplements, were as effective as the flower extracts. The researchers exposed cells to a 25-microgram/millilitre concentration of the extract. The cells, which were also exposed to insulin, absorbed less glucose as a result.

When the researchers determined the protein production of the fat cells, they got the figure shown below. The extract had deactivated PPAR-gamma, the molecular sensor with which fat cells observe fatty acids. CTL & V = control groups.

“A current hypothesis is that Type 2 diabetes can be viewed as a failure to appropriately expand fat mass in the context of a positive energy balance”, the researchers write. “In light of this notion, the ability of Saint John’s Wort to inhibit adipogenesis may not be metabolically favorable.”

Maybe not for people with diabetes-2. But for fighting fit athletes, it may be a different matter.

Source:
Biochem Biophys Res Commun. 2009 Jul 30. [Epub ahead of print].

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