Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for OLIVE are as follows:

Possibly effective for…

  • Breast cancer. Women who consume more olive oil in their diet seem to have a lower risk of developing breast cancer.
  • Constipation. Taking the oil by mouth can help to soften stools in people with constipation.
  • Diabetes. People who eat higher amounts of olive oil (about 15-20 grams per day) seem to have a lower risk of developing diabetes. Eating more than 20 grams per day is not linked with an additional benefit. Research also shows that oil can improve blood sugar control in people with diabetes. Olive oil in a Mediterranean-type diet might also reduce the risk of “hardening of the arteries” (atherosclerosis) compared to polyunsaturated oils such as sunflower oil in people with diabetes.
  • High cholesterol. Using the oil in the diet instead of saturated fat may reduce total cholesterol levels in people with high cholesterol. But other dietary oils might reduce total cholesterol better than olive oil.
  • High blood pressure. Adding generous amounts of extra virgin oil to the diet and continuing with the usual treatments for high blood pressure can improve blood pressure over 6 months in people with high blood pressure. In some cases, people with mild to moderate high blood pressure can actually lower their dose of blood pressure medication or even stop taking medication altogether. However, do not adjust your medications without your healthcare provider’s supervision. Taking olive leaf extract also seems to lower blood pressure in patients with high blood pressure.

Possibly ineffective for…

  • Earwax. Applying oil to the skin does not appear to soften earwax.
  • Ear infection (otitis media). Applying olive oil to the skin does not appear to reduce pain in children with ear infections.
  • Insufficient evidence to rate effectiveness for…
  • Eczema (atopic dermatitis). Early research suggests that applying a mixture of honey, beeswax, and the oil along with standard care seems to improve eczema.
  • Colon cancer, rectal cancer. Research suggests that people who consume more olive oil in their diet might have a lower risk of developing colorectal cancer.
  • Airway infections caused by the exerciser. Early research shows that taking leaf extract doesn’t prevent the common cold in student-athletes. But it might help female athletes use fewer sick days.
  • A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Early research shows that taking 30 grams of oil before breakfast for 2-4 weeks helps get rid of Helicobacter pylori infections in some people.
  • A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome). A metabolic syndrome is a group of conditions such as high blood pressure, excess body fat around the waist, or high blood sugar that can increase the risk of heart attack, stroke, or diabetes. Taking olive leaf extract seems to help control blood sugar in men with this condition. But it does not seem to reduce body weight, cholesterol levels, or blood pressure.
  • Migraine. Taking olive oil daily for 2 months seems to reduce the frequency and severity of migraine headaches. However, more research is needed.
  • Osteoarthritis. Developing research shows that taking a freeze-dried water extract of olive fruit or an extract of olive leaf decreases pain and increases mobility in people with osteoarthritis.
  • Stretch marks. Early research shows that applying a small amount of olive oil to the stomach twice daily starting early in the second semester does not prevent stretch marks during pregnancy.
  • Stroke. Eating a diet high in olive oil might reduce the chance of having a stroke compared to a similar diet with less olive oil.
  • Ringworm (Tinea corporis). Early research suggests that applying a mixture of honey, beeswax, and olive oil to the skin is beneficial for treating ringworm.
  • Jock itch (Tinea cruris). Early research suggests that applying a mixture of honey, beeswax, and olive oil to the skin is beneficial for treating jock itch.
  • A common fungal infection of the skin (Tinea versicolor). Early research suggests that applying a mixture of honey, beeswax, and olive oil to the skin is beneficial for treating yeast infection.

More evidence is needed to rate the effectiveness of olive for these uses.

Olive Side Effects

  • When taken by mouth: Olive oil is LIKELY SAFE when taken appropriately by mouth. Olive oil can be used safely as 14% of total daily calories. This is equal to about 2 tablespoons (28 grams) daily. Up to 1 liter per week of extra-virgin olive oil has been used safely as part of a Mediterranean-style diet for up to 5.8 years. Olive oil might cause nausea in a very small number of people. Leaf extract is POSSIBLY SAFE when taken appropriately by mouth.
  • There is insufficient reliable information available about the safety of olive leaf when taken by mouth.
  • When applied to the skin: Olive oil is LIKELY SAFE when applied to the skin. Delayed allergic responses and contact dermatitis have been reported. When used in the mouth following dental treatment, the mouth may feel more sensitive.
  • When inhaled: Olive trees produce pollen that can cause seasonal respiratory allergy in some people.

Warnings & Precautions

  • Pregnancy and breast-feeding: There isn’t enough reliable information to know if olive is safe to use when pregnant or breast-feeding. Do not use amounts greater than the amount commonly found in foods.
  • Diabetes: Olive oil might lower blood sugar. People with diabetes should check their blood sugar when using olive oil.
  • Surgery: Olive oil might affect blood sugar. Using the oil might affect blood sugar control during and after surgery. Stop taking it 2 weeks before surgery.

Olive Dosage

The following doses have been studied in scientific research:


  • For constipation: 30 mL of olive oil.
  • For preventing heart disease: 54 grams of olive oil per day (about 4 tablespoons) has been used. As a part of a Mediterranean diet, consuming up to 1 liter of extra-virgin olive oil per week has also been used.
  • For preventing diabetes. A diet rich in olive oil has been used. Doses of 15-20 grams per day seem to work best.
  • For high cholesterol: 23 grams of olive oil per day (about 2 tablespoons) providing 17.5 grams of monounsaturated fatty acids in place of saturated fats in the diet.
  • For high blood pressure: 30-40 grams per day of extra-virgin oil as part of the diet. 400 mg of olive leaf extract four times daily has also been used for high blood pressure.


Consult your doctor or pharmacist.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.