Dear Una McDermott

Many thanks for your email regarding Prunus laurocerasus and the conflicting reports of edibility and poisonousness.

Prunus laurocerasus is in the rose family of plants. This family includes many well-known edible fruits including the apple, pear, plum, strawberry, cherry, apricot, peach, blackberry and raspberry. A very high proportion of plants in the rose family also contain cyanogenic glycosides. This is found, in small quantities, in the leaves and seeds, but also in the fruits and can be detected by the characteristic bitter flavour reminiscent of almonds. Indeed, it is these glycosides that give almonds (also a member of the rose family) their characteristic flavour. Whilst the sweet almonds that are so commonly used as an article of food have only a low concentration of these glycosides, the bitter almonds that are used commercially to make marzipan and other food flavourings contain a much higher content (indeed there are records of three of these bitter almond seeds causing death in a young child). Even the sweet almonds are not totally safe to eat - it has been stimulated that about 900 seeds would constitute a lethal dose for an average healthy adult.

These glycosides are not all bad, however. Indeed, they are used both by conventional medicine and by herbalists as a stimulant for the respiratory system. In conventional medicine, the compound is used in isolation, but herbally many plants rich in these glycosides are used, including the bitter almond and Prunus laurocerasus (the leaves and seeds rather than the fruits).

The fruits of Prunus laurocerasus are usually quite low in glycoside content and are thus completely safe to eat in all but very large quantities. I have eaten quite large quantities on a number of occasions and have also given them to my young children who love them. However, I always make sure the fruit is fully ripe (it acquires a jelly-like consistency) and that it has a sweet rather than bitter flavour. Eaten like this they are completely safe - I first gave them to my son when he was about 2½ years old and he is now a very healthy 7½ year old.

The leaflet on ground cover plants that you read was written about 10 years ago and has not been revised since then. I do feel that the explanation on edibility should be expanded and will make sure that this is done in the near future. The entry for the plant in our database is more clear - I include excerpts from it below:-

The entry for known toxins reads as follows - "All parts of the plant contain hydrogen cyanide, a poison that gives almonds their characteristic flavour. This toxin is found mainly in the leaves and seed and is readily detected by its bitter taste. It is usually present in too small a quantity to do any harm but any very bitter seed or fruit should not be eaten. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, it is also claimed to be of benefit in the treatment of cancer. In excess, however, it can cause respiratory failure and even death."

The entry for edibility reads as follows -

"Fruit - raw or cooked. Sweet and reasonably pleasant when fully ripe[65, 74, K]. The cultivar 'Camelliifolia' bears huge quantities of fruit[K]. This is the size of a large cherry and, when fully ripe, has a reasonable flavour raw with a jelly-like texture and a slight astringency[K]. Some sources suggest the fruit is poisonous, this probably refers to the unripe fruit[7]. We have eaten this fruit in quite large quantities without the slightest ill effects (this also includes a 2 year old child) and so any toxicity is of a very low order[K]. However, any fruit that is bitter should not be eaten in quantity because the bitterness is caused by the presence of the toxic compounds - see the notes above on toxicity. The fruit is about 8mm in diameter and contains one large seed[200]. Water distilled from the leaves is used as an almond flavouring[2, 46, 61, 183]. It should only be uses in small quantities, it is poisonous in large amounts[183]. Seed - raw or cooked. Do not eat the seed if it is too bitter - see the notes above on toxicity."

I hope this is of us to you. Please do not hesitate to get back in touch with me if you have further questions.

Ken Fern