The Doctrine of Signatures was an important aspect of folk medicine from the Middle Ages often associated with the work of herbalists, wise women and native peoples from around the world. It drew upon the belief that natural objects that looked like a part of the body could cure diseases that would arise there (ex. Walnuts, which closely resemble a brain, have brain-boosting benefits). This belief became known as the ‘Doctrine of Signatures’ after the appearance of a book by the German mystic Jakob Boehme called The Signature of All Things (1621). Of course not all foods resemble organs they are nutritionally aligned with...but it's cool when they do.
Another beautiful example of this is the womb-shaped avocado, which takes approximately nine months to grow from blossom to ripened fruit and contains an unusually large seed (‘baby’) in its centre. Avocados are rich in specific nutrients needed during pregnancy, such as folate, potassium, vitamin B6, C & K, fiber and healthy fats, which help to feel satiated and improve brain function.
Other curious examples of The Doctrine of Signatures at work include:
Tomatoes – Heart
Known for their affinity with heart health, these bright red fruits strongly resemble a heart, in both shape and colour, and when sliced open they reveal four chambers just like a heart. Countless studies have linked tomatoes to heart health, and the prevention of heart-related illness.
Grapes - Lungs
Clusters of grapes strongly resemble the branches of alveoli that comprise our lungs. These fruits, high in anti-oxidants, have been shown to help lung disorders such as asthma and even lung cancer.
Figs - Testicles
Figs are known to increase sperm count and mobility. Figs grow in pairs and when opened reveal thousands of white seeds.
Celery – Bones
Stick-straight, hard celery closely resembles a bone and has identical amounts of sodium to bones (23%) as well as a high amount of calcium.
Sweet Potatoes – Pancreas
The elongated shape and orange colour of a sweet potato bears an uncanny resemblance to the elongated orange coloured Pancreas. Studies have shown that sweet potatoes can help stabilize blood sugar levels by releasing sugars gradually into the bloodstream. It also helps lower insulin resistance as well, making it a great low glycemic food for diabetics.