Borage: The Cucumber-Scented Herb, Its Uses and Its Alkaloid Problem

Want cucumber flavor from an herb? That’s borage (Borago officinalis), a bristly annual with bright blue, star-shaped flowers. Cooks use the young leaves raw in salads and in Frankfurt’s green sauce, with the flowers as a garnish. Keep it away from the heat, which wipes out most of its fragrance fast. And it comes with a real safety caveat: like many plants in its family it contains pyrrolizidine alkaloids, and the European Union sets legal limits for them in borage leaves.

At a glance

What borage is

Borage is a hairy annual that can grow to about 60 cm (2 feet). It has big, rough, oblong leaves and loose, drooping clusters of starlike bright blue flowers. Bees love the flowers, and the plant is sometimes grown as an ornamental to feed honeybees.

The English name traces back, through French and Spanish, to Medieval Latin borrago. Katzer reports that the word is generally thought to be Arabic in origin and gives two proposed sources: abu buraq, “father of sweat”, and abu huras, “father of roughness”. Neither one is settled. Katzer also points out that borage shares names with related rough-leaved plants, listing bugloss (Echium) and oxtongue (Anchusa).³

Flavor and aroma

The leaves smell and taste cool and cucumber-like. Katzer calls the taste rather weak and very much like fresh cucumber, and names 2,6-nonadienal as the main compound in the leaf’s tiny amount of essential oil (below 0.1%).³

Heat is borage’s enemy. Boiling, frying and simmering quickly wipe out most of its fragrance, which is why it’s best raw. Pick the youngest leaves for eating raw. Older ones get coarser and more bristly.

Where it comes from

Sources don’t agree on where borage started out:

We go with Kew as the botanical authority. Kew lists a long run of introductions across Europe, the Americas, Asia and Oceania, so borage now grows far beyond the Mediterranean.

History

Borage has collected plenty of stories: that it was Homer’s nepenthe, that Roman soldiers drank it before battle, that early herbalists loved it as a cure for melancholy, and that Charles Dickens put it in his punch. We couldn’t trace any of them to a source we could open, so we’re not repeating them as fact.

How borage is used

• Salads. The leaves and flowers go into salads. Katzer thinks that light cucumber fragrance suits salads of raw vegetables best.
• Frankfurt green sauce. Borage’s most famous dish is Frankfurt’s Grüne Soße. The traditional seven herbs are parsley, chervil, chives, cress, sorrel, burnet and borage. Several have their own pages: parsley, chervil, chives, sorrel and salad burnet. See also German spices.
• As a vegetable. In Europe the leaves are also cooked as a vegetable. Since heat kills the aroma, think of cooked borage as a mild green, not a cucumber-scented herb.
• Soups, stews and drinks. Dried or fresh leaves season stews and soups and flavor wine cups and other drinks.
• Flowers. Besides going in salads, the blue flowers are sometimes tried as a food coloring.³ You’ll often see candied and fried borage flowers mentioned, but we found no source to cite for them.

Buying and storage

We didn’t find a shelf life for fresh or dried borage anywhere. So much of the aroma disappears with heat, and there’s so little essential oil to begin with, that dried borage keeps little of the fresh leaf’s character.

Safety: pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PAs) are extremely common in the borage family, and they’re powerful liver toxins. Katzer notes that eating them over time can cause severe liver damage. He adds that borage has been argued to be unsafe in folk medicine, while the risk from casual cooking use is probably negligible.³ That second call is his, not a regulator’s.

The European Union does regulate PAs in borage. Its contaminants regulation sets maximum levels for the sum of a defined list of PAs:⁴

These limits cover products sold in the EU. We found no matching US limit.

Health claims

Borage seed oil is rich in polyunsaturated fatty acids, with γ-linolenic acid (GLA) at around 20%, per Katzer.³ That GLA is in the seed oil. The leaves you cook with don’t carry it in any useful amount.

Most of the human evidence on borage oil is about eczema. A 2013 Cochrane systematic review of 27 studies (1,596 participants) of oral evening primrose oil and borage oil found that borage oil didn’t significantly improve overall eczema symptoms compared with placebo, and concluded that neither oil is an effective eczema treatment.⁵

We couldn’t trace claims that borage leaves are a significant source of vitamins, minerals or fiber, or that borage protects against heart disease. We’re not claiming borage treats or prevents anything.

Related herbs

Salad burnet sits next to borage in Frankfurt green sauce, and it’s your closest stand-in when you want a fresh, cucumber-like note.