We love rhubarb for its fruity, acidic taste. But did you know that too much rhubarb can be toxic to humans? We explain why, and give you a few precautions to take to avoid its harmful effects.
Oxalic acid, a harmful substance in excessive quantities
Rhubarb is a stem vegetable (not a fruit) that we love to make into desserts. Although it has many nutritional properties, it should be eaten in moderation. Rhubarb contains oxalic acid, a substance that can be harmful to humans, as it can promote the formation of kidney and bladder stones. Oxalic acid can also attack tooth enamel, leading to tooth poisoning.
But there’s no need to panic if you enjoy rhubarb! You need to eat a lot of it to be at risk. In fact, the critical dose of oxalic acid is around 5 g for an adult. However, there are between 0.2 and 0.5 g of oxalic acid per 100 g of rhubarb.
A few precautions to be aware of when eating rhubarb
To enjoy rhubarb while avoiding too much oxalic acid, here are a few precautions to be aware of:
- Rhubarb leaves and skin are richer in oxalic acid. That’s why it’s best to eat only the stalks, and take care to peel them.
- Young rhubarb plants contain the lowest levels of oxalic acid. In other words, as rhubarb matures, its oxalic acid concentration increases.
- Red rhubarb varieties contain less oxalic acid than green rhubarb varieties.
- To reduce oxalic acid levels, rhubarb is best eaten cooked rather than raw.