From Soil to Brain: How Olive Oil and Intermittent Fasting Boost Each Other

Nutrients has published a review, “From Soil to Brain,” which brings together everything that influences the health benefits of olive oil: variety and soil, pressing technologies, storage and cooking, consumer choice, and even intermittent fasting. The authors analyze the biochemistry of extra-virgin olive oil (EVOO), show how its polyphenols and monounsaturated fats combine with the metabolic effects of fasting, and conclude that properly selected and used EVOO can enhance the anti-inflammatory and antioxidant effects of fasting approaches, improving insulin sensitivity and reducing oxidative stress. At the same time, the researchers emphasize that clinical trials are needed to clarify the “dose, timing, and context” of use.

Background of the study

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet with a reputation as a "health product". Its effect is not only in the fat profile with a predominance of monounsaturated oleic acid, but also in the "minor" fraction: polyphenols (hydroxytyrosol, oleocanthal, oleuropein and ligstroside aglycones), tocopherols, squalene, triterpenes. It is polyphenols that are associated with antioxidant and anti-inflammatory action, improved endothelial function, metabolic profile and potential neuroprotection. There is even a separate formulation in the EU regulation: olive oil polyphenols help protect blood lipids from oxidative damage (with sufficient content and daily dose of the product).

The quality of EVOO is formed "from field to shelf": the variety and maturity of olives, climate and soil, hygiene of harvesting and speed of processing, extraction scheme (only mechanical pressing without solvents) and storage conditions. The more aggressive the cleaning and heating, the poorer the oil in polyphenols - hence the contrast between extra-virgin/virgin and refined categories or oils from pomace. Temperature and light are important in the kitchen: prolonged overheating and storage in bright light accelerate oxidation and loss of phenols, while dark containers, coolness and reasonable cooking modes help preserve the "healthy" fraction. Sensory bitterness and "stinging in the throat" in high-quality EVOO just reflect the presence of phenolic compounds.

Intermittent fasting (time-restricted eating, 5:2, etc.) is becoming a popular metabolic tool: it improves insulin sensitivity, reduces postprandial inflammation, shifts energy metabolism towards lipolysis and ketogenesis, and activates autophagy pathways (AMPK↑/mTOR↓). In this framework, EVOO is a convenient “partner”: small amounts help to endure pauses due to satiety, do not cause sharp glycemic fluctuations, and its polyphenols add an anti-inflammatory and antioxidant contribution. At the “refeeding” stage, the oil supports bile secretion and absorption of fat-soluble nutrients, and in combination with plant foods, it improves the absorption of polyphenols and carotenoids.

At the same time, the evidence base for the “synergy” of EVOO and intermittent fasting in humans is still patchy: a lot of mechanistic and observational data, but few standardized randomized trials with dosages, timing, and clinical outcomes. Questions remain about culinary regimens (where are the “loss-free” temperature boundaries), chrononutrition (when is the oil absorbed optimally), and individual restrictions (cholelithiasis, pancreatitis - personal tactics are needed). Therefore, the current consensus is practical and cautious: choose high-quality EVOO (extra-virgin), consume it as part of a predominantly plant-based diet, combine it wisely with meal regimens - and wait for the results of larger clinical studies.

Oil quality: what determines the grade, pressing and purification

The benefits of EVOO start long before the kitchen. The content of polyphenols and "minor" bioactive molecules is affected by the cultivar, climate/soil, maturity, harvest sanitation, and extraction method. On the shelf, we see four product categories established by EU regulations: extra-virgin, virgin, refined olive oil, and pomace oil; there is also a technical fraction called lampante, which cannot be consumed without subsequent purification. The key idea is that the more aggressive the processing (long-term storage of pomace, heating, solvents, refining), the poorer the oil in natural antioxidants.

A short navigator on oil types

• EVOO - free acidity ≤0.8%; polyphenols typically 150-1000 mg/kg; mechanical pressing without solvents.
• Virgin - less stringent sensory/acid criteria; still mechanically pressed.
• Refined - physical and chemical purification, almost completely loses polyphenols and tocopherols.
• Olive-pomace - extraction of pomace (including n-hexane), then refining; useful minors are minimal.
• Lampante - low-grade raw material/defects; not suitable for food without refining.

An interesting detail: olives themselves contain 20-30 g/kg of polyphenols, but due to their “water-loving” nature, about 0.5 g/kg (0.05%) gets into the finished EVOO after pressing, the rest goes into the pulp and waste water or is destroyed during refining. This is why careful technologies and freshness are critical.

EVOO Composition: "Heavy" Fat and "Light Cavalry" of Polyphenols

The basis of EVOO is formed by monounsaturated fatty acids (≈75%), primarily oleic (ω-9); the proportion of ω-6 linoleic is usually 3.5-21%, ω-3 α-linolenic - <1.5%. The "minor" fraction contains squalene, tocopherols, triterpenes, phytosterols, pigments, volatile aldehydes/ketones and, of course, polyphenols: hydroxytyrosol, oleuropein (and its aglycone), oleocanthal, ligstroside, etc. Some of them explain the characteristic bitterness and "stinging in the throat" of high-quality oils.

Oleocanthal, a phenol EVOO with COX inhibition by a mechanism reminiscent of NSAIDs, and hydroxytyrosol, which can be formed both from olive glycosides and endogenously (through dopamine metabolism pathways), stand out separately. Hence, the contribution to anti-inflammatory and neuroprotective effects.

Fasting + EVOO: a biochemical “duet”

Intermittent fasting and time-restricted eating improve insulin sensitivity, enhance lipolysis, turn on autophagy, and rewire AMPK/mTOR signaling. EVOO, for its part, reduces postprandial inflammation, modulates antioxidant gene expression, and minimally interferes with ketogenesis when consumed in small amounts during “modified” fasts. The result may be synergy: less NF-κB signaling, better mitochondria, and a more stable lipid profile.

What makes EVOO a convenient partner for fasting approaches

• helps to endure hunger by providing satiety;
• does not “undermine” key metabolic pathways of fasting (ketogenesis, lipolysis) in small doses;
• during "refeeding" it gently reactivates digestion and bile secretion;
• adds anti-inflammatory and antioxidant effects, which fasting already has a lot of.

It is no coincidence that in studies like PREDIMED, high adherence to the Mediterranean diet with added EVOO was associated with lower blood pressure, better lipid profiles, and lower cardiovascular risk.

Chrononutrition: When Oil Works Best

Metabolic processing of fats and lipid clearance are subject to circadian rhythms, with peak effectiveness in the morning/first half of the day. Polyphenols are also “clock-dependent”: intestinal permeability, enzyme activity, and liver metabolism fluctuate throughout the day, affecting their bioavailability. Hence the practical tip of the review: shift the bulk of EVOO consumption to daytime meals, especially in older adults, whose circadian rhythms are often “blurred.”

Cooking and storage: how not to lose the benefits

EVOO is generally stable compared to many seed oils (high oleic fat + polyphenols), but conditions and temperatures matter. Long-term industrial frying changes the composition (NMR studies show this), microwave heating accelerates oxidative degradation, while cooking in the company of food components helps inhibit oxidation.

Storage is a separate science. The oil feels best in a dark container at a low temperature and low oxygen in the "head" of the bottle (2-5%): this way polyphenols, chlorophylls and sensorics are preserved longer. With "supermarket" lighting, ~45% of phenols can be lost in 4 months; at the same time, over time, the hydrolysis of complex phenols sometimes increases the level of hydroxytyrosol/tyrosol - the composition is dynamic. Regular cans are also ok if the temperature is low (about 6 °C); at 26 °C, especially in tin, rancidity accelerates.

Mini cheat sheet for everyday life

• buy the current season's harvest and keep the bottle closed, in a dark and cool place;
• for everyday frying, moderate temperatures and a fresh batch of oil are suitable;
• Avoid repeated prolonged overheating and microwaving of the oil itself;
• Don't trust the "golden glare" of shop windows - light is the enemy of polyphenols.

What the regulator and label say

In the EU, the EFSA-approved health claim is: "Olive oil polyphenols protect blood lipids from oxidative damage" - but only if the oil contains at least 5 mg of hydroxytyrosol and its derivatives per 20 g and the consumer actually consumes at least 20 g of oil per day. On average, according to the literature, EVOO contains about 0.05% polyphenols, but the range between varieties and technologies is large.

WHO recommendations resemble a general framework: fats <30% of energy, priority - unsaturated; trans fats <1% of energy. Against this background, 20-30 ml of EVOO per day in adults is a clear "working" value, consistent with data on cardiovascular outcomes. And do not forget that lampante without refining cannot be consumed as food - this is a signal of raw material/processing defects.

For whom is this particularly relevant?

People with metabolic syndrome, prediabetes/type 2 diabetes, cardiovascular risks, and possibly vulnerability to neurodegeneration. It is in these areas that the fasting + EVOO duo has the most overlap in mechanisms (AMPK, autophagy, anti-inflammatory cascades). But the strategy should be applied within the framework of a general diet and for the tasks of a specific person.

Restrictions

This is a review, not an RCT: some of the conclusions rely on mechanistic and mixed-design studies. The effects of fasting on the microbiota in humans are heterogeneous, and for culinary regimens, the map of newly formed compounds and their impact on health still needs to be “drawn.” The authors explicitly call for randomized clinical trials that will clarify the dosage, timing, and “use mode” of EVOO in conjunction with interval protocols.

Source: Dumitrescu I.-B., Drăgoi CM, Nicolae AC From Soil to Brain: Olive Oil Attributes, Consumer Choices, Intermittent Fasting, and Their Impact on Health. Nutrients. 2025;17(11):1905. https://doi.org/10.3390/nu17111905