And they were delighted with the results.
One of the extra ingredients added was vitamin B12, which is also found in paracetamol.
Gesink said: "It is actually the only vitamin which can be dissolved in water, and that is why you can brew with it."
Other ingredients are willow fibres for a cleansing effect, ginger against sickness, and sea salts to keep the body from dehydrating.
Customers who tasted the beer at the pub were pleasantly surprised.
One customer said while tasting: "It is malty, delicious. Different than a normal lager beer. It has much more character."
Gesink said: "It works like a charm. But of course it would not work with vast amounts, it still contains alcohol."
He said that after four or five beers, a person would still be left feeling fresh in the morning.
The bad news is that so far the beer is only for sale at the De Prael brewery, where it's available in draft.
Those who fancy a tipple might need to be quick, as "people do drink a lot of it" according to the brewers.