itemprefab1 = modutilities.CreateItemPrefab('Dummy item', 'Useless item', 10)

itemprefab1.OnUse = function() print("Used the dummy item") return false end
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itemprefab2 = modutilities.CreateItemPrefab('Stale bread', 'Useless bread', 69)

itemprefab2.OnUse = function() return modutilities.GetGameVariables().TryEat(0.2) end
------------------------------------
itemprefab3 = modutilities.CreateItemPrefab('Mental health bread', 'Restore all your mental health!', 123)

function onEat()
	--gamevariables contains all variables of the currently loaded game
	gv = modutilities.GetGameVariables()
	--You can add mental health(or any other value) like this
	gv.MentalHealth = gv.MentalHealth + 1.0
end

itemprefab3.OnUse = function() return modutilities.GetGameVariables().TryEat(0.2, onEat)end;
------------------------------------

item1 = modutilities.CreateNewItem(0, CurrentModGuid, itemprefab1)
item2 = modutilities.CreateNewItem(5, CurrentModGuid, itemprefab2)
item3 = modutilities.CreateNewItemAutoAssignId(CurrentModGuid, itemprefab3)

modutilities.AddGenericItemToShop('grocery', item1, nil)
modutilities.AddGenericItemToShop('grocery', item2, nil)
modutilities.AddSingleBuyItemToShop('grocery', item3, nil)