Israeli scientists say they may have identified a way to reduce dosage in humans of the antidepressant fluoxetine — widely sold as Prozac — which could cut down on unwanted side effects.
The team from the Biomolecular Sciences Department at the Weizmann Institute of Science found that beta-sitosterol, a plant-derived substance sold as a dietary supplement and used largely by people trying to reduce cholesterol levels, lowered anxiety levels in mice. The substance is naturally found in avocados, pistachios, almonds and other nuts — though in quantities far smaller than those that showed an effect on the mice.
In the study, the team found that mice given beta-sitosterol were less anxious than others. For example, they were not nervous walking into the brightly lit center of an enclosure, whereas other mice who weren’t given beta-sitosterol were careful to stay on the darker periphery, avoiding the stress of the bright light. They also navigated a maze more calmly.
When the supplement was given alongside fluoxetine, the two substances reduced the anxiety of mice at lower doses compared with the amounts needed to produce the same effect when they were administered separately.
“This research is hopeful because when a treatment reduces anxiety levels in mice, it represents a candidate for scientists to treat the effects of stress and depression in humans,” Dr. Nicolas Panayotis, one of the authors, told The Times of Israel.
Panayotis and his team published their findings Tuesday in the peer-reviewed journal Cell Reports Medicine. They now hope to progress their research from mice to humans and see whether beta-sitosterol may be used to treat depression.
Panayotis’s research indicates that beta-sitosterol could be useful as a standalone treatment. But when given alongside fluoxetine, it actually reduced the amount of the drug needed to reduce anxiety in mice. And given that smaller doses mean less side effects, which can include an impact on state of mind as well as nausea, drowsiness and dizziness, if this translates to humans it could help many people.
Beta-sitosterol is not known to have major side effects.
“One of the big problems of Prozac is the side effects, which can include making people feel very inhibited, so any progress that can reduce side effects is important,” said Panayotis. “We are optimistic that our research could allow this supplement, which already has a very high safety profile as it’s in widespread use, reduce doses and therefore side effects.”
This option is attractive as it could allow doctors to rely on the tried-and-tested qualities of Prozac while addressing the problem of side effects, according to Panayotis.
In view of these results, his team hopes to move to human trials to assess potential benefits of giving humans beta-sitosterol, or a combination of beta-sitosterol alongside Prozac.
Panayotis said: “The next stage in research is to try to validate our results, which have so far been seen only among mice, in humans. As the supplement is already approved for humans, we can move this along quickly.”