The Effect of Olive Leaf Extract on the Thyroid

If you suffer from a slow or sluggish thyroid, consuming medicines made from olive leaves may help to regulate your thyroid function. Olive leaves are rich in protective antioxidants which protect your body from free radical damage and support immune, heart and digestive health. Olive leaves are not intended to replace medical care, and you should always check with a registered medical herbalist and doctor before purchasing olive leaf products.


The olive tree, also known as Olea europaea, has been cultivated by humans for thousands of years, going back to ancient Greece where the tree became a symbol of peace, prosperity and health. According to Susanna Lyle, Ph.D., author of "Eat Smart, Stay Well," the olive tree was also grown in ancient Spain and Italy, with each country developing its own unique cultivars 1. Olive fruits are an edible source of nutrition and healing, and the leaves have received recent attention as an herbal medicine for treating viral infections, high cholesterol and thyroid problems.


Olive leaves contain a variety of antioxidant chemicals which are responsible for many of its medicinal properties. Iridoid compounds such as oleuropein, oleuroside and oleoside are the most well-known olive leaf constituents. According to a study published in "Natural Products Research" in 2005, researchers from Portugal identified the presence of many other antioxidant flavonoids in olive leaves, including rutin, apigenin, luteolin. All of them are likely to contribute to the plant's free radical scavenging, antimicrobial and anti-inflammatory properties.


In a study published in "Phytotherapy Research" in 2002, researchers from King Saud University in Saudi Arabia investigated the effects of olive leaf on the thyroid. Rats were fed extracts of olive leaf for 14 days, at which time researchers ran blood tests to check for thyroid hormone levels. Olive leaf had a significant effect on the thyroid, stimulating a strong increase in triiodothyronin, and a smaller increase on thyroxin -- two important thyroid hormones responsible for regulating metabolism. In addition, olive leaf decreased levels of thyroid-stimulating hormone -- a chemical secreted by the pituitary to stimulate thyroid activity. These results show olive leaf has a direction action on the thyroid gland, and may help to balance thyroid hormones in people suffering from thyroid diseases.

Safety and Toxicity

According to Drug Information Online, olive leaf is nontoxic, well-tolerated and safe for use in the general population. No side effects have been reported with using olive leaf extract. Limited information on its during pregnancy and lactation means that you should be cautious when using olive leaf if you are pregnant or breast-feeding. Consult your doctor before purchasing olive leaf extract, as it may interact with thyroid and diabetic medications.