IN an earlier article in this column, we have noted safety data for fennel (Foeniculum vulgare). It pertains to the LD50 threshold of 1.038 ml of fennel essential oil per kilogram body weight of laboratory mice. LD50 refers to “lethal dose at 50 percent death rate,” which means that half of the mice injected with that dose died of toxicity.
The good news is, if you weigh 60 ml today, you need 60 ml of injected fennel essential oil to experience toxic effects, which can be threatening to your life as it killed half of the mice in an experiment. However, you can avoid the toxic effect if (1) you drink it instead of having it injected (however, do not drink 120 ml) and (2) divide the intake dose into four intakes. For example, so that when the new quarter dose hits your bloodstream, the earlier dose had been off your bloodstream already and working their wonders already.
However, it is important that a disclosure must be made, particularly in commercial supplements that use it in their ingredients, on its content of estragole. A pure estragole has a margin of exposure (MOE) of 129 to 471. Meanwhile, the European Food Safety Authority (EFSA) warned that an MOE of more than 10.0 must be considered as a “priority human risk.”
Fortunately, the estragole content in sweet fennel essential oil usually does not go beyond 10 percent, while that in the bitter variety is far lower at 2.5 percent. Therefore, the key issue in fennel toxicity is the dose taken. This means that you must be aware on the dose your food supplement contains to avoid getting an overdose of fennel essential oil.
The good news is, there are components in fennel essential oil that tend to moderate the toxic effect of estragole. Anethole, for instance, which comprised around 80 percent of the essential oil, is a reputed anticancer.
Since most commercial supplement products in the market today are in the powdered form, this tip will come a long way in deciding your approach in using fennel for your liver protection diet. Crushed or powdered seeds are not very useful preparations if you want the benefits of fennel essential oil.
Five researchers (Gori and colleagues) from the University Hospital of Florence warned that powdered seeds gradually lose their essential oil the longer they stay in the shelf even with sealed bottles. Their report came off the press in 2012 in the Evidence-Based Complementary and Alternative Medicine journal.
The option, thus, is to purchase fresh fennel seeds and powder them yourself before use.