Is Drinking Olive Oil and Lemon Juice on an Empty Stomach Really Good for You?

When a conventionally attractive celebrity shows up on screen and talks about their new favourite 'wellness' tips, it's not long before the internet obsesses over it. These health fads are often "too good to be true"-esque remedies or rituals that allegedly support a number of frustrations such as weight loss.

A recent such trend? Drinking olive oil mixed with lemon juice first thing in the morning on an empty stomach. According to enthusiasts, this practice can improve heart health, aid digestion, and even detoxify the body. But have you ever wondered if all those purported benefits are clinically backed? 

Read on to unearth the truth and dispel the myths on olive oil and lemon juice concoctions.

Check out Key Takeaways at the end for a quick summary

The Benefits of Olive Oil: Heart Health and Antioxidant Power

In the past decade, many studies and analyses have been conducted on the Mediterranean diet. Why? Because of all the benefits that come with adopting it in daily life. A 2017 review found that adherence to the diet led to “reduced risk of overall mortality, cardiovascular diseases, [...] overall cancer incidence, neurodegenerative diseases and diabetes” (Dinu et al., 2017). In 2013, a systemic review found that the diet was “associated with better cognitive function, lower rates of cognitive decline, and reduced risk of Alzheimer’s” (Lourida et al., 2013). At this point, calling the Mediterranean diet ‘healthy’ is a no-brainer. 

That’s where olive oil comes into play. Olive oil, particularly extra virgin olive oil (EVOO) is a cornerstone of the Mediterranean diet. It’s rich in monounsaturated fats, primarily oleic acid, which have been linked to improved cardiovascular health. A landmark study known as the PREDIMED trial, published in the New England Journal of Medicine, demonstrated that a Mediterranean diet supplemented with EVOO reduced the risk of major cardiovascular events, like heart attacks and strokes, by about 30% compared to a low-fat diet (Estruch et al., 2013). This suggests that incorporating olive oil into a well-balanced diet could support heart health over the long term.

Beyond its healthy fats, olive oil contains powerful antioxidants, notably polyphenols. These compounds help fight oxidative stress, a process where free radicals damage cells and contribute to chronic diseases like atherosclerosis. Research published in the Annals of Internal Medicine found that olive oil phenolics can protect low-density lipoprotein (LDL) particles (“bad” cholesterol) from oxidative damage (Covas et al., 2006). This antioxidant action may also reduce inflammation, further benefiting the heart. 

How Lemon Juice Supports Digestion and Detoxification

Something about lemon just sounds so clean, doesn’t it? It makes you feel like it’ll be just as effective at cleaning your insides as it is at cleaning kitchen grime. Not to mention, lemon juice is a popular ingredient in home remedies, often touted as a digestion aid, a ‘detox formula’, as well as a source of antioxidants. Lemon juice boasts a good amount of vitamin C and flavonoids, which contribute to its antioxidant properties (Zahr et al., 2023). It sounds great on paper, but these compounds are most likely modest compared to the body’s natural systems. 

Still, lemon juice may have some real digestive benefits. In a human study using MRI scans, researchers found that consuming diluted lemon juice with a starchy meal increased gastric volume and sped up gastric emptying compared to water, suggesting lemon juice could support meal processing and satiety (Freitas et al., 2022). Another study found that citric acid, a key component of lemon juice, enhances the intestinal absorption of calcium and phosphorus in rats (Lacour et al., 1997). While citric acid is also used as part of bowel prep formulas for its osmotic properties (Mankaney et al., 2021), drinking lemon juice casually is unlikely to have a laxative effect unless consumed in large amounts.

As for “detoxing,” that’s where the science hits pause. The liver and kidneys are already highly efficient at removing waste products and toxins, and there’s little to no evidence that detox diets in general enhance these systems (Klein & Kiat, 2014). Most detox claims are anecdotal at best, and misleading at worst. Lemon juice does provide hydration, antioxidants, and a touch of flavour, but the idea that it flushes toxins from your body is more marketing than medicine.

Does Taking Them on an Empty Stomach Boost Absorption and Effectiveness?

The central question of this practice is whether drinking olive oil and lemon juice on an empty stomach makes them more effective. In theory, taking them without food might allow the body to absorb their nutrients or compounds more readily, free from interference by other dietary components. However, scientific evidence for these claims are glaringly lacking.

For olive oil, its monounsaturated fats and polyphenols are typically absorbed well when consumed with food, as fats often enhance the uptake of fat-soluble nutrients. Drinking it alone might not offer the same advantage for other vitamins, though some anecdotal reports suggest it could have a mild laxative effect due to its lubricating properties in the digestive tract. There is no evidence as of yet to suggest that drinking it alone on an empty stomach is more beneficial than consuming it through other methods such as a part of salad dressings, so any digestive benefit remains purely speculative.

Some people believe that taking vitamin C on an empty stomach enhances its absorption, but scientific evidence doesn’t fully support that idea. What we do know is that vitamin C absorption depends more on dose than on whether it’s taken with or without food. Research shows that absorption is nearly complete at lower doses (under 200 mg), but becomes less efficient as the dose increases—dropping below 50% when you exceed 500 mg in one go (National Institutes of Health, 2021). Whether it comes from food, juice, or supplements, vitamin C is generally well absorbed, and the body regulates its levels tightly through the intestines and kidneys (Padayatty et al., 2004). So while timing your vitamin C around meals won’t hurt, there’s no strong evidence that it dramatically boosts or reduces how much your body takes in.

Is There Real Synergy When Taken Together?

Could combining olive oil and lemon juice create a health benefit greater than the sum of their parts? This concept, known as synergy, is appealing but requires scientific backing. A study in the Journal of the Science of Food and Agriculture offers some insight, suggesting that the presence of an oil matrix (which includes olive oil) may improve the bioaccessibility of certain flavonoids in lemon juice (Kamiloglu et al., 2022). The acidity of lemon juice might help preserve oil stability as well (Kamiloglu et al., 2022).

Additionally, the combination could theoretically aid digestion by emulsifying the oil, making it less harsh on the stomach. However, this is largely hypothetical. While the aforementioned study is promising, it’s a small piece of evidence, and more research is needed to confirm whether this synergy translates into measurable health improvements. For now, the combined effect seems plausible but not definitive.

What Do Experts Say About Safety and Proper Usage?

Both olive oil and lemon juice are considered safe for most people when consumed in moderation. The U.S. Food and Drug Administration (FDA) recognizes olive oil as a safe food, and lemon juice is a common dietary staple. However, there are some caveats to drinking them, especially in large amounts or on an empty stomach.

Olive oil is calorie-dense, with about 120 calories per tablespoon. Drinking too much could lead to unintended weight gain, and in some cases, it might cause nausea or gastrointestinal discomfort, particularly if you’re not used to it. For individuals with gallstones, olive oil could trigger gallbladder contractions, so caution is advised.

Lemon juice, being acidic, poses risks like dental enamel erosion if consumed undiluted over time. It might also irritate the stomach lining in sensitive individuals. Diluting it with water is a common recommendation to mitigate these effects.

Experts, such as those from the American Heart Association, endorse olive oil as a heart-healthy fat but typically suggest using it in cooking or dressings rather than drinking it straight. There’s no official guidance on the empty-stomach practice, but a reasonable starting point might be a teaspoon of each—about 5 mL—to test tolerance. Likewise, Health Canada acknowledges the benefits of unsaturated fats like those in olive oil but doesn’t comment on this specific habit.

Ultimately, anyone considering this should consult a healthcare professional, especially if they have pre-existing conditions or take medications that might interact with acidic or fatty substances.

Sources/Further Reading

1. Covas, M.-I., Nyyssönen, K., Poulsen, H. E., Kaikkonen, J., Zunft, H.-J. F., Kiesewetter, H., Gaddi, A., de la Torre, R., Mursu, J., Bäumler, H., Nascetti, S., Salonen, J. T., Fitó, M., Virtanen, J., & Marrugat, J. (2006). The Effect of Polyphenols in Olive Oil on Heart Disease Risk Factors. Annals of Internal Medicine, 145(5), 333. https://doi.org/10.7326/0003-4819-145-5-200609050-00006
2. Dinu, M., Pagliai, G., Casini, A., & Sofi, F. (2017). Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomised trials. European Journal of Clinical Nutrition, 72(1), 30–43. https://doi.org/10.1038/ejcn.2017.58
3. Esposito, K., Maiorino, M. I., Ceriello, A., & Giugliano, D. (2010). Prevention and control of type 2 diabetes by Mediterranean diet: A systematic review. Diabetes Research and Clinical Practice, 89(2), 97–102. https://doi.org/10.1016/j.diabres.2010.04.019
4. Estruch, R., Ros, E., Salas-Salvadó, J., Covas, M.-I., Corella, D., Arós, F., Gómez-Gracia, E., Ruiz-Gutiérrez, V., Fiol, M., Lapetra, J., Lamuela-Raventos, R. M., Serra-Majem, L., Pintó, X., Basora, J., Muñoz, M. A., Sorlí, J. V., Martínez, J. A., & Martínez-González, M. A. (2013). Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. New England Journal of Medicine, 368(14), 1279–1290. https://doi.org/10.1056/nejmoa1200303
5. Freitas, D., Boué, F., Benallaoua, M., Airinei, G., Benamouzig, R., Lutton, E., Jourdain, L., Dubuisson, R.-M., Maître, X., Darrasse, L., & Le Feunteun, S. (2022). Glycemic response, satiety, gastric secretions and emptying after bread consumption with water, tea or lemon juice: a randomized crossover intervention using MRI. European Journal of Nutrition, 61(3), 1621–1636. https://doi.org/10.1007/s00394-021-02762-2
6. Kamiloglu, S., Ozdal, T., Tomas, M., & Capanoglu, E. (2022). Oil matrix modulates the bioaccessibility of polyphenols: a study of salad dressing formulation with industrial broccoli by‐products and lemon juice. Journal of the Science of Food and Agriculture, 102(12), 5368–5377. https://doi.org/10.1002/jsfa.11890
7. Klein, A. V., & Kiat, H. (2014). Detox diets for toxin elimination and weight management: a critical review of the evidence. Journal of Human Nutrition and Dietetics, 28(6), 675–686. https://doi.org/10.1111/jhn.12286
8. Lacour, B., Tardivel, S., & Drüeke, T. (1997). Stimulation by citric acid of calcium and phosphorus bioavailability in rats fed a calcium-rich diet. Mineral and Electrolyte Metabolism, 23(2), 79–87. https://pubmed.ncbi.nlm.nih.gov/9252973/
9. Lourida, I., Soni, M., Thompson-Coon, J., Purandare, N., Lang, I. A., Ukoumunne, O. C., & Llewellyn, D. J. (2013). Mediterranean diet, cognitive function, and dementia: a systematic review. Epidemiology, 24(4), 479–489. https://doi.org/10.1097/EDE.0b013e3182944410
10. Mankaney, G. N., Ando, M., Dahdal, D. N., & Burke, C. A. (2021). Safety and efficacy of sodium picosulfate, magnesium oxide, and citric acid bowel preparation in patients with baseline renal impairment or diabetes: subanalysis of a randomized, controlled trial. Therapeutic Advances in Gastroenterology, 14. https://doi.org/10.1177/17562848211024458
11. National Institutes of Health. (2021, March 26). Vitamin C. National Institutes of Health; National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/
12. Padayatty, S. J., Sun, H., Wang, Y., Riordan, H. D., Hewitt, S. M., Katz, A., Wesley, R. A., & Levine, M. (2004). Vitamin C Pharmacokinetics: Implications for Oral and Intravenous Use. Annals of Internal Medicine, 140(7), 533. https://doi.org/10.7326/0003-4819-140-7-200404060-00010
13. Zahr, S., Zahr, R., El Hajj, R., & Khalil, M. (2023). Phytochemistry and biological activities of Citrus sinensis and Citrus limon: an update. Journal of Herbal Medicine, 41, 100737. https://doi.org/10.1016/j.hermed.2023.100737