When You Eat Olive Oil Every Day, This Is What Happens To You

Trying to keep track of which oils to use and which to avoid can leave your head spinning. Coconut oil, for instance, can go from superfood to artery-clogger and back again in the blink of an eye. But olive oil has maintained its popularity and solid reputation for years, and there's good reason for that. According to a 2021 paper published in Frontiers in Plant Science, many of olive oil's purported health benefits stem from the oleic acid it contains. This omega-9 fat makes up 55–83% of the total fat in olive oil.

Olives contain 20–30% oil, and there are four different levels of olive oil quality. The best of the best is extra virgin olive oil, which is made from the first pressing of the olives and has the best taste. Virgin olive oil is also made from the first pressing but uses lower-quality olives. Pure olive oil is a mixture of virgin and refined oil, while refined olive oil, despite its classy name, is of the lowest quality (via Britannica).

For centuries, olive oil has been an integral part of the Mediterranean diet, often touted as one of the healthiest and most sustainable ways of eating. Olive oil serves as the main source of fat in this diet and is a part of most meals (via UCSF). Even if most of us aren't following the Mediterranean diet, we're definitely on board with using olive oil. In 2020, Americans consumed approximately 386,000 metric tons of the stuff (via Statista). But what happens to your body if you eat olive oil every day, and are there any downsides to this seemingly perfect oil?

You'll get plenty of antioxidants

Olive oil is more than just a source of fat. According to the 2018 book "Functional Foods," olive oil contains more than 200 bioactive compounds, many of which have antioxidant properties (via IntechOpen). The chief antioxidants in olive oil include tocopherols (different forms of vitamin E), beta carotene, lutein, squalene, and phenols (organic compounds found in plants). The antioxidant phenols found in olive oil include hydroxytyrosol, tyrosol, oleuropein, and oleocanthal.

But what exactly is an antioxidant and why are they so important? Antioxidants are chemicals that protect the body against damage from free radicals. Free radicals are highly unstable atoms of oxygen that try to "steal" electrons from other molecules in the body. This destabilizes the molecules and creates a chain reaction that leads to damage throughout the cells and tissues of the body, a process known as oxidative damage or oxidative stress. Substances that produce free radicals can be found in food and in our environment, and free radicals are also created as the byproduct of natural chemical processes in the body. Antioxidants are able to give free radicals the electrons they want without becoming destabilized themselves, thus neutralizing free radicals before they can cause damage (via Live Science).

Your cholesterol may improve

Heart disease is the leading cause of death in the United States. According to the Centers for Disease Control and Prevention (CDC), about 659,000 Americans die each year of heart disease — one death every 36 seconds. Heart disease is actually an umbrella term for a number of conditions, but coronary artery disease (CAD) is the most common type of heart disease. It's caused by a buildup of plaque in the arteries that supply the heart. When it comes to CAD, high cholesterol is one of the biggest risk factors (via Healthline). Fortunately, regularly consuming olive oil can help.

A 2015 paper published in Evidence-Based Complementary and Alternative Medicine noted that olive oil lowered LDL ("bad") cholesterol and triglycerides, while simultaneously increasing HDL ("good") cholesterol. In addition, it appears to reduce the likelihood that cholesterol will become oxidized (and thus harmful) in the body. The researchers pointed out that olive oil also improves HDL's ability to do its main job of transporting cholesterol away from arteries and back to the liver, where it can be recycled. They credit the phenolic compounds in olive oil, particularly hydroxytyrosol and oleuropein, with these cholesterol-balancing benefits.

Your blood pressure may be easier to control

Olive oil can also combat heart disease by lowering blood pressure. In a 2020 literature review published in Nutrients, researchers concluded that consuming olive oil in quantities ranging from 10 to 60 milliliters daily consistently reduced systolic blood pressure (the pressure in the arteries when the heart is contracting) and, to a lesser extent, also reduced diastolic blood pressure (the pressure in the arteries when the heart is relaxed between beats). These positive effects on blood pressure were particularly pronounced when individuals who'd already been diagnosed with cardiovascular disease began consuming olive oil.

The paper's authors credited the high oleic acid and antioxidant polyphenol content of olive oil for these effects and speculated that these compounds improved blood pressure by encouraging vasodilation (expansion of the arteries) and reducing inflammation. They cautioned, however, that olive oil isn't necessarily a magic bullet that can be used in isolation. Based on the studies they analyzed, the researchers concluded that olive oil was only effective in reducing blood pressure when it was consumed as part of a healthy Mediterranean diet.

You may be able to prevent a stroke

The Mayo Clinic identified three types of stroke. Ischemic strokes are the most common and occur when the blood vessels supplying the brain become blocked with arterial plaque or a clot. A transient ischemic attack (TIA), also known as a "ministroke," is similar, but the blockage is only temporary and does not cause permanent brain damage. A hemorrhagic stroke occurs when a blood vessel leaks or ruptures. Having high blood pressure or high cholesterol significantly increases a person's chances of having a stroke. According to the Centers for Disease Control and Prevention, roughly 7.8 million Americans will have at least one stroke in their lifetime.

Given olive oil's beneficial effects on both cholesterol and blood pressure, it's no surprise that regularly consuming it has been linked to a lower risk of stroke, according to a 2014 paper published in The British Journal of Nutrition. The researchers noted that while studies examining the link between olive oil and reduced risk for heart disease often produced mixed results, studies consistently showed a strong link between eating olive oil and reduced risk of stroke. Interestingly, a 2014 study published in Lipids in Health and Disease concluded that olive oil was the only source of monounsaturated fats that reduced stroke risk. Monounsaturated fats from other sources didn't have the same brain-protecting effects.

You'll fight chronic inflammation

Many of the antioxidant compounds found in olive oil also have anti-inflammatory properties. According to a 2014 paper published in the International Journal of Molecular Sciences, the phenol oleocanthal has anti-inflammatory properties similar to those of ibuprofen, and diets high in oleocanthal-rich olive oil have been linked to lower incidence of inflammatory diseases.

A 2010 study published in the Canadian Medical Association Journal also noted that consuming monounsaturated fats, such as those found in olive oil, significantly reduces individuals' levels of C-reactive protein (CRP). CRP is an indicator of inflammation in the body, and CRP levels are often elevated in those with inflammatory diseases (via Mayo Clinic).

Although it often gets a bad rap, inflammation isn't always a bad thing. According to the Harvard Medical School, acute inflammation occurs immediately after an injury and produces warmth, redness, swelling, and pain. This brings white blood cells to the area, where they can begin the healing process. Problems arise, however, if the inflammatory response becomes chronic. In these cases, the body can get confused and begin attacking healthy tissue. Chronic, low-grade inflammation is believed to cause or worsen a number of conditions, such as heart disease, diabetes, cancer, and arthritis. Chronic inflammation doesn't produce the telltale signs that acute inflammation causes, so it often goes unnoticed and unaddressed.

Your risk for certain types of cancer may reduce

According to the National Cancer Institute, more than 18.1 million new cases of cancer are diagnosed in the United States each year, and cancer remains one of the leading causes of death. The most commonly diagnosed cancers include breast, lung, prostate, and colorectal cancers, as well as melanoma. While many factors can contribute to cancer risk, a diet high in olive oil appears to reduce your risk for certain types of cancer.

A 2016 paper published in Current Nutrition Reports noted that a high intake of olive oil as part of following the Mediterranean diet was associated with reduced risk for breast cancer, cancers of the digestive tract (including stomach, pancreatic, and colorectal cancers), and lung cancer. In another paper, published in Cancer Epidemiology, Biomarkers & Prevention, researchers estimated that as high as 25% of colorectal cancer cases, 15% of breast cancer cases, and 10% of prostate, pancreatic, and endometrial cancer cases could be prevented by switching from the standard American diet to the olive oil–rich Mediterranean diet.

According to the 2018 book "Functional Foods," the cancer-fighting compounds in olive oil include oleuropein, oleocanthal, hydroxytyrosol, and squalene (via InTechOpen). These substances prevent DNA damage that can lead to the formation of cancer. They also prevent the out-of-control cell proliferation that allows tumors to grow, and they promote cell apoptosis — the destruction of diseased or damaged cells before they can cause harm.

You'll strengthen your immune system

Move over orange juice, there's a new immune booster in town. According to a 2015 study published in Nutrition & Metabolism, eating 3 tablespoons of extra virgin olive oil daily was associated with greater growth and activation of T cells, specialized immune cells that attack bacteria, viruses, and other foreign invaders. Participants who consumed the same amount of corn oil, butter, or soybean oil didn't see the same results. The researchers noted that olive oil's high levels of polyphenols and monounsaturated fatty acids are likely to thank for the immune benefits.

In a 2010 paper published in Nutrition Hospitalaria, the authors noted that polyunsaturated fats like omega-3s are great at reducing inflammation (part of our body's natural immune response), but in doing so they also partially suppress our immune system's ability to fight off pathogens. The monounsaturated fat in olive oil, on the other hand, can reduce chronic inflammation without negatively affecting the body's infection-fighting abilities.

Olive oil may be particularly beneficial for those with autoimmune conditions, in which the immune system gets confused and begins attacking healthy tissue, creating large amounts of chronic inflammation. A 2016 study published in Food & Function noted that the compounds found in extra virgin olive oil may be particularly beneficial for controlling conditions such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, and sclerosis.

You'll reduce your risk for type 2 diabetes

Diabetes is a major public health issue in the United States. According to the American Diabetes Association, 34.2 million Americans (more than 10% of the population) have diabetes. Of these, the vast majority (32.6 million) have type 2 diabetes. Poorly managed diabetes can lead to a number of serious complications and the condition is the seventh leading cause of death in the United States.

The good news is that regularly consuming olive oil appears to lower your risk for type 2 diabetes. Like all fats, olive oil, when consumed as part of a meal with carbs, slows the absorption of glucose. The fat prevents the glucose from hitting your system all at once, heading off blood sugar spikes that, over time, can lead to insulin resistance and diabetes (via SF Gate). But the oleic acid in olive oil may set it above other fats when it comes to diabetes prevention.

In a 2017 study published in Nutrition & Diabetes, people who ate the most olive oil had lower fasting blood sugar levels and a 16% reduced risk of developing type 2 diabetes. Even for those who've already been diagnosed with diabetes, adding more olive oil to their diet could be useful. The same study noted that participants with diabetes saw even greater reductions in their fasting blood sugar levels than participants who didn't have diabetes. Diabetic participants also saw a 27% reduction in their hemoglobin A1C levels, a measure of how well the body has managed glucose levels over the last two to three months.

You will maintain your bone health

Milk isn't the only liquid that can keep your bones strong into old age. In a 2018 study published in Nutrients, researchers examined more than 500 Spanish women to determine how various dietary factors affected their bone density. They found that those individuals who consumed the most olive oil had the highest bone density, even after accounting for factors like calcium and vitamin D intake. The study authors noted that the phenols in olive oil likely help maintain bone density by encouraging bone formation, inhibiting bone breakdown, and reducing overall levels of inflammation.

Even after we reach adulthood, our bones are constantly being built up and torn down. Cells called osteoblasts create new, strong bone, while osteoclasts break down old bone. Osteoporosis occurs when more bone is broken down than built, leading to brittle bones that are more prone to fracture. Osteoporosis affects about 25% of older women and 5% of older men (via Healthline).

According to the Arthritis Foundation, chronic inflammation is one of a number of factors that reduce bone density. Chronic inflammation produces high levels of cytokines (a type of protein), and these cytokines trigger osteoclast activity, leading to increased rates of bone breakdown. So, by fighting chronic inflammation, olive oil helps keep your skeleton sturdy as you age.

You'll help keep Alzheimer's disease at bay

According to the Alzheimer's Association, "Alzheimer's is the most common cause of dementia, a general term for memory loss and other cognitive abilities serious enough to interfere with daily life." The disease accounts for 60 to 80% of all dementia cases. Most individuals with Alzheimer's are over age 65, but the condition is not a normal part of aging. Although the exact cause of Alzheimer's is unknown, a buildup of protein fragments called beta-amyloid plaques and tau tangles within brain cells that prevent them from functioning properly is a likely culprit. Alzheimer's disease is the sixth leading cause of death in the United States. The condition claimed the lives of over 121,000 individuals in 2018 (via CDC).

Because olive oil is so beneficial to the vascular system, it may reduce the risk for Alzheimer's disease. As a 2019 paper published in Revue Neurologique explained, vascular factors play a huge role in the development of Alzheimer's, so olive oil, as part of a healthy Mediterranean diet, could help prevent the disease. Although more research is needed, early studies on mice appear to support this hypothesis. In a study conducted on mice and published in ACS Chemical Neuroscience in 2013, researchers found that oleocanthal, a type of phenol found in olive oil, improved the rate at which beta-amyloid plaques were cleared from the rodents' brains.

Your weight could change

Regardless of its health benefits, there's no denying that olive oil, as pure liquid fat, is calorically dense. According to WebMD, a single tablespoon of the stuff has 126 calories, all of them from fat (14 grams). And if you're only using a single tablespoon at a time, you deserve an award for self-control. Because olive oil is a low-volume, high-calorie food, it makes sense that eating it regularly might cause you to rack up extra calories. Based on the energy balance model of weight management, consuming more calories than you burn will lead to weight gain, while burning more calories than you consume will result in weight loss (via WebMD).

But there's plenty of research to suggest that olive oil may actually support weight loss. A 2018 study published in the European Journal of Nutrition found that overweight women who added at least one tablespoons of extra virgin olive oil to their breakfast lost more body fat than participants who added soybean oil to their morning meal. Research from 2006 published in Lipids noted that eating olive oil as part of following the Mediterranean diet isn't associated with weight gain and doesn't increase an individual's risk for becoming overweight or obese.

Your sex life may improve

If you're a man struggling with erectile dysfunction (ED), you're not alone. According to the Cleveland Clinic, depending on age, between 5% and 15% of men have complete ED, while the incidence of mild and moderate ED tends to correspond to age. Many men turn to Viagra to improve their sexual functioning, but research suggests that olive oil may be just as effective.

HuffPost reported on a Greek study of 660 men that found that those who replaced butter with olive oil while following the Mediterranean diet saw significant improvements in their sex lives. Olive oil helps keep blood vessels dilated and free of arterial plaques. This improves blood flow, which is critical for maintaining an erection. Olive oil also raises testosterone levels.

In another study, published in 2013 in Natural Products Communications, researchers evaluated the effects of olive oil and argan oil on the testosterone and luteinizing hormone (LH) levels of Moroccan men. (Although luteinizing hormone is often thought of as a female sex hormone, it also plays an important role in male sexual health.) The study found that after three weeks olive oil had increased testosterone by 17.4% and LH by 42.6%.

You'll fight stomach ulcers

Although stomach ulcers were once thought to be the result of stress, we now know that a bacteria, Helicobacter pylori (H. pylori) causes more than 90% of cases of this painful condition. About two-thirds of the world's population is infected with H. pylori, which infiltrates the lining of the stomach, although many will never have ulcers. Stomach ulcers do, however, affect approximately 25 million Americans. In situations in which H. pylori is causing an ulcer, the infection is treated with antibiotics (via Illinois Department of Public Health).

If you're worried about H. pylori infection, consuming olive oil every day could be helpful. According to a 2007 study published in the Journal of Agricultural and Food Chemistry, some of the phenolic compounds in olive oil, particularly decarboxymethyl ligstroside aglycon, have antibacterial properties. The researchers found that these compounds could kill eight different strains of H. pylori, three of which are resistant to conventional antibiotics. It's important to note, however, that this experiment was performed in a lab using bacteria cultured in a petri dish, not performed on actual humans or animals. However, another study, published in 2012, was conducted on humans and found that a daily dose of 30 grams of olive oil was moderately effective in eliminating H. pylori infection.