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Raspberry ketone: the fat burner

Raspberries contain a substance that resembles synephrine. Chemists call it 4-(4-hydroxyphenyl) butan-2-one; in everyday language it's called raspberry ketone. According to researchers at the Japanese Ehime University and the Kanebo company, the compound stimulates fat burning. In mice, at least.

Raspberry ketone: the fat burner

Raspberry ketone
Raspberry ketone is already on the market. It's in AMP2, Ergopharm's successor to the notorious AMP. Raw materials supplier Integrity sells the compound as the standard Razberi-K. It's also in slimming supplements like Lipofuze, which according to the American is the best selling slimming supplement at the moment. [ April 08, 2011] In Spectra Force Research Liquibolics Razberi-K, raspberry ketone is actually the only active ingredient.

In 2005 Japanese researchers published the results of an animal study which showed that raspberry ketone [structural formula shown here] promotes weight loss. The researchers set up the study because of the resemblance between the structural formula of raspberry ketone and that of synephrine, adrenalin and ephedrine.

Adrenalin Tyrosine Ephedrine Synephrine





The Japanese gave a group of mice food containing large amounts of extra fat for six weeks [HFD]. Once they'd got used to the fat, the HFD mice quickly put on weight. This didn't happen to the mice that were given ordinary food [ND]. And in the HFD mice that were also given 1 percent raspberry ketone in their diet, the increase in body weight was less.

Adding raspberry ketone led to a reduction in growth of some fat tissues.

Raspberry ketone: the fat burner

Raspberry ketone: the fat burner

Raspberry ketone: the fat burner

The Japanese did experiments with white fat cells to measure the amount of fatty acids released in relation to the concentration of glycerol in their test tubes. The higher the glycerol concentration, the more stored fatty acids were released by the fat cells.

If the fat cells were not exposed to noradrenalin, the raspberry ketone showed no effect. When they were exposed to noradrenalin, the fat cells released more fat cells from fatty acids the higher the raspberry ketone concentration was. Apparently raspberry ketone needs noradrenalin to work.

The researchers also discovered that raspberry ketone does not attach itself to the beta-adrenergic receptors in the fat cell.

Raspberry ketone probably works directly via the enzyme hormone-sensitive lipase. This enzyme is activated via the beta-adrenergic receptors. The researchers showed that, as a result of raspberry ketone, more hormone-sensitive lipase goes to the vesicles in which the fat cells store their fatty acids. Hormone-sensitive lipase gets fat cells to mobilise and excrete fatty acids.

By the way, we don't think that the raspberry ketone in slimming supplements comes from real raspberries. The cosmetics and food industry has been using the substance for years as a colouring and flavour agent. There are bound to be bioreactors that produce the compound cheaply.

Life Sci. 2005 May 27; 77(2): 194-204.

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