Monounsaturated Fats: What They Are, Where to Find Them, and Why Olive Oil Leads
Monounsaturated fats are fats whose fatty acids carry a single double bond — in practice, almost entirely oleic acid, the fatty acid that makes up most of olive oil. They sit between saturated fats (no double bonds) and polyunsaturated fats (two or more), and that one bond explains most of what is worth knowing about them: why they are liquid in the cupboard, why they hold up reasonably well in a pan, and why the body can make them itself. On USDA FoodData Central, about 74% of extra virgin olive oil's fatty acids are monounsaturated. This guide ranks the oils and foods richest in monounsaturated fat using USDA entries we read on 12 October 2026, quotes the exact EU and UK label wording, and explains why olive oil, while not top of every table, leads in the kitchen.
For our own oil, see our Cold-Pressed Single-Estate Extra Virgin Olive Oil - Marrakech (500ml).
The Short Answer
- A monounsaturated fat has one double bond. The main one in food is oleic acid, an omega-9 fatty acid; on USDA's figures it accounts for 67.8 g of the 69.2 g of monounsaturated fat in 100 g of extra virgin olive oil.
- The richest oils are olive, hazelnut, avocado and the "high-oleic" sunflower and safflower oils. High-oleic sunflower oil tops the USDA table at 86% of its fatty acids, ahead of hazelnut oil (82%), olive oil (74–75%) and avocado oil (74%).
- The richest whole foods are nuts, avocados and olives. Macadamias and hazelnuts are about 80% monounsaturated by fatty acids; almonds, pecans and cashews about 60–66%.
- Monounsaturated fat is not only a plant fat. Lard is 47% monounsaturated on USDA's figures — more monounsaturated than saturated — which is why the whole balance of a fat matters, not one number.
- The evidence is about swapping. In the UK DIVAS trial (Vafeiadou and colleagues, 2015), replacing some saturated fat with monounsaturated fat for 16 weeks lowered LDL cholesterol by 11.3% compared with a diet rich in saturated fat.
- EU and UK law permits a claim worded around that swap. Foods high in unsaturated fat may say that replacing saturated fats with unsaturated fats "contributes to the maintenance of normal blood cholesterol levels".
- Olive oil leads because it is the monounsaturated fat people cook with. In its extra virgin form it is pressed from fruit and unrefined, so it brings flavour and polyphenols that neutral, refined oils do not.
What Is a Monounsaturated Fat?
A monounsaturated fat is a fat built mainly from monounsaturated fatty acids — fatty-acid chains with exactly one carbon-to-carbon double bond. In food, the dominant one is oleic acid, an 18-carbon fatty acid with its double bond at the ninth carbon from the omega end, which is why it is called an omega-9. Olive oil, avocados, hazelnuts and almonds are the familiar sources.
That single bond puts a kink in the chain, so the molecules cannot pack as tightly as saturated ones. The practical result is that monounsaturated oils are liquid at room temperature but start to thicken and turn cloudy in the fridge — a good olive oil left in the cold often looks almost solid, then clears again as it warms. Saturated fats such as butter and coconut oil stay solid; oils rich in polyunsaturated fat stay runny even when chilled.
Oleic acid, palmitoleic acid and omega-9
Oleic acid is not the only monounsaturated fatty acid, just by far the most common. USDA's entry for raw macadamia nuts lists 13 g of palmitoleic acid (a 16-carbon monounsaturated fatty acid) per 100 g alongside 43.8 g of oleic acid, which makes macadamias unusual. Unlike omega-3 and omega-6 fats, omega-9 fatty acids are not essential: the body can make oleic acid itself, so there is no requirement to eat it — only a choice about which fats to eat instead of others.
Monounsaturated vs Polyunsaturated vs Saturated Fat
Every food fat is a mixture of all three types; a food gets labelled by whichever dominates. The table sets out the differences that matter at the table and in the pan.
| Saturated | Monounsaturated | Polyunsaturated | |
|---|---|---|---|
| Double bonds per fatty acid | None | One | Two or more |
| Main example in food | Palmitic acid | Oleic acid (omega-9) | Linoleic acid (omega-6), alpha-linolenic acid (omega-3) |
| State at room temperature | Usually solid | Liquid; thickens when chilled | Liquid, even when chilled |
| Essential in the diet? | No | No — the body makes oleic acid | Yes, for linoleic and alpha-linolenic acid |
| Reaction to heat and air | Most stable | Fairly stable | Least stable — more double bonds to oxidise |
| Typical sources | Butter, ghee, lard, coconut and palm oil | Olive, rapeseed and hazelnut oil; avocados; most nuts | Sunflower, corn and soybean oil; walnuts; flaxseed; oily fish |
The two unsaturated types are complementary rather than rivals. Polyunsaturated fats supply the essential omega-6 and omega-3 fatty acids the body cannot make; monounsaturated fats are the steadier, more heat-tolerant everyday fat. UK guidance treats both as the fats to eat in place of some saturated fat. For a fuller look at the polyunsaturated side, our article on olive oil's omega-3, 6 and 9 profile works through a tablespoon in detail.
Which Oil Is Highest in Monounsaturated Fat?
On USDA FoodData Central, high-oleic sunflower oil is the highest in monounsaturated fat of the common cooking oils, at 83.7 g per 100 g — about 86% of its fatty acids. Hazelnut oil follows at about 82%, then high-oleic safflower oil (79%), olive oil (74–75%) and avocado oil (74%). Rapeseed oil is about 64%, and ordinary sunflower oil only 20%.
The table below takes each oil's saturated, monounsaturated and polyunsaturated figures straight from its USDA entry and shows monounsaturated fat as a share of the three added together.
| Oil (USDA FDC entry) | Monounsaturated per 100 g | Saturated per 100 g | Polyunsaturated per 100 g | Monounsaturated share of fatty acids | Monounsaturated per tablespoon (13.5 g) |
|---|---|---|---|---|---|
| Sunflower oil, high oleic (172338) | 83.7 g | 9.86 g | 3.8 g | 86% | 11.3 g |
| Hazelnut oil (171427) | 78 g | 7.4 g | 10.2 g | 82% | 10.5 g |
| Safflower oil, high oleic (171027) | 75.2 g | 7.54 g | 12.8 g | 79% | 10.2 g |
| Olive oil (171413) | 73 g | 13.8 g | 10.5 g | 75% | 9.9 g |
| Extra virgin olive oil (748608, Foundation) | 69.2 g | 15.4 g | 9.07 g | 74% | 9.3 g |
| Avocado oil (173573) | 70.6 g | 11.6 g | 13.5 g | 74% | 9.5 g |
| Rapeseed (canola) oil (172336) | 63.3 g | 7.36 g | 28.1 g | 64% | 8.5 g |
| Peanut oil (171410) | 46.2 g | 16.9 g | 32 g | 49% | 6.2 g |
| Lard (171401) | 45.1 g | 39.2 g | 11.2 g | 47% | 6.1 g |
| Butter, salted (173410) | 21 g | 51.4 g | 3.04 g | 28% | 2.8 g |
| Sunflower oil, regular (171025) | 19.5 g | 10.3 g | 65.7 g | 20% | 2.6 g |
| Coconut oil (171412) | 6.33 g | 82.5 g | 1.7 g | 7% | 0.9 g |
Two entries deserve a note. "High-oleic" sunflower and safflower oils come from plant varieties developed by breeding to make oleic acid instead of linoleic acid, which is why ordinary sunflower oil sits near the bottom of the same table. And USDA's extra virgin olive oil entry is a Foundation record built from analysed samples, while its general "olive oil" entry is an older SR Legacy record; they are different datasets, so the small gap between them should not be read as a difference between grades.
Monounsaturated Fat Foods: The List
Oils are concentrated fat, so they top any per-gram table. Whole foods carry less fat per bite but bring fibre, protein and other nutrients with it. These are the whole foods richest in monounsaturated fat on USDA's figures:
- Macadamia nuts — 58.9 g per 100 g, about 81% of their fatty acids.
- Hazelnuts — 45.7 g per 100 g, about 79%.
- Pecans — 40.8 g per 100 g, about 60%.
- Almonds — 31.6 g per 100 g, about 66%.
- Peanut butter — 25.9 g per 100 g, about 53%.
- Cashews — 23.8 g per 100 g, about 60%.
- Avocado — 9.8 g per 100 g, about 71%.
- Olives — 7.65 g per 100 g of canned ripe olives, about 73%.
| Food (USDA FDC entry) | Typical portion | Monounsaturated fat in that portion | Saturated fat in that portion |
|---|---|---|---|
| Extra virgin olive oil (748608) | 1 tablespoon (13.5 g) | 9.3 g | 2.1 g |
| Macadamia nuts, raw (170178) | 30 g handful | 17.7 g | 3.6 g |
| Hazelnuts (170581) | 30 g handful | 13.7 g | 1.3 g |
| Pecans (170182) | 30 g handful | 12.2 g | 1.9 g |
| Almonds (170567) | 30 g handful | 9.5 g | 1.1 g |
| Avocado, raw (171705) | 100 g (roughly half a fruit) | 9.8 g | 2.1 g |
| Olives, ripe, canned (169094) | 30 g | 2.3 g | 0.7 g |
| Egg, whole, raw (171287) | 50 g (one medium egg) | 1.8 g | 1.6 g |
Brazil nuts are a useful contrast: they are listed by the NHS among nuts with monounsaturated fat, but USDA's entry (170569) puts them at 23.9 g monounsaturated, 24.4 g polyunsaturated and 16.1 g saturated per 100 g, so only about 37% of their fat is monounsaturated. If you want a nut chosen for its monounsaturated fat, macadamias, hazelnuts and almonds are the stronger picks.
What the Research Shows About Swapping In Monounsaturated Fat
The best evidence for monounsaturated fat comes from trials that change what replaces saturated fat, not from adding more fat. The clearest UK example is DIVAS, published by Vafeiadou and colleagues at the University of Reading in the American Journal of Clinical Nutrition in 2015. In this randomised, controlled, single-blind trial, 195 men and women aged 21–60 with moderately raised cardiovascular risk scores followed one of three diets for 16 weeks, each with the same total fat (36% of energy): one rich in saturated fat, one in which about 9.5% of energy moved from saturated to monounsaturated fat, and one in which it moved to omega-6 polyunsaturated fat.
Compared with the saturated-fat diet, the monounsaturated diet lowered fasting total cholesterol by 8.4% and LDL cholesterol by 11.3%, and the polyunsaturated diet by 9.2% and 13.6%. Neither swap changed the trial's primary measure, flow-mediated dilatation (a test of how well an artery widens), or other measures of vascular function. It is one trial of blood markers over four months, not of long-term health outcomes — but it is a direct, well-run test of the monounsaturated swap in UK adults.
What a label is allowed to say
EU law, and UK law through its assimilated version, controls exactly what a food label may claim. We read both regulations on legislation.gov.uk on 12 October 2026. Regulation (EC) No 1924/2006 allows "high monounsaturated fat" only where at least 45% of the product's fatty acids come from monounsaturated fat and monounsaturated fat provides more than 20% of its energy; "high unsaturated fat" needs at least 70% of the fatty acids from unsaturated fat. Commission Regulation (EU) No 432/2012 then permits this health claim, only for foods that are high in unsaturated fat: "Replacing saturated fats with unsaturated fats in the diet contributes to the maintenance of normal blood cholesterol levels [MUFA and PUFA are unsaturated fats]". For olive oil and the trials behind it, see our article on olive oil and cholesterol.
Run USDA's numbers through those rules and the logic of the law becomes clear. Olive oil clears both thresholds comfortably. Lard, at 47% monounsaturated, would clear the arithmetic for "high monounsaturated fat" — but at about 60% unsaturated it falls short of "high unsaturated fat", so it could not carry the cholesterol claim. The rule rewards the whole balance of the fat, not a single headline figure.
The Honest Limits of Monounsaturated Fat
A careful reader will raise three fair objections.
"If lard is nearly half monounsaturated, is it a healthy fat?" Not by the measure that matters. Per 100 g, USDA lists 39.2 g of saturated fat in lard against 13.8 g in olive oil, and the NHS lists lard among foods high in saturated fat. Monounsaturated fat helps when it replaces saturated fat; a fat that brings a lot of both does not make that swap.
"High-oleic sunflower oil has more monounsaturated fat than olive oil — so isn't it better?" On that single column, yes, and it is a perfectly reasonable cooking oil. But it is a seed oil bred for that profile and prized for tasting of very little. Extra virgin olive oil is pressed from the fruit and is unrefined by definition, which is where its flavour and polyphenols come from.
"Fat is fat — won't more of it mean more calories?" Yes. Every fat, saturated or unsaturated, provides 9 kcal per gram, against 4 kcal for carbohydrate and protein. DIVAS kept total fat and energy the same and changed only the type. Pouring extra oil onto an unchanged diet is not what the evidence describes.
Why Olive Oil Leads
Olive oil is not the most monounsaturated oil in the USDA table, and it does not need to be. It leads for three reasons that the table alone does not show.
It is the monounsaturated fat people actually cook with
Nuts and avocados add monounsaturated fat to a meal; the cooking and dressing fat is what replaces butter, ghee or lard in it. Using USDA's figures, a tablespoon of extra virgin olive oil carries about 2.1 g of saturated fat against about 6.9 g in the same weight of salted butter — and about 9.3 g of monounsaturated fat against 2.8 g. That is the swap DIVAS tested, made at the stove every day.
It is mainly oleic acid, in an unrefined oil
Of the 69.2 g of monounsaturated fat in USDA's extra virgin olive oil entry, 67.8 g is oleic acid. Because extra virgin oil is obtained by mechanical means alone, it keeps the minor compounds — polyphenols, flavour, colour — that refining strips out. Those polyphenols carry their own permitted EU claim under Regulation (EU) No 432/2012, but only for olive oil containing at least 5 mg of hydroxytyrosol and its derivatives per 20 g, a figure that has to be measured in a laboratory rather than inferred from the words "extra virgin".
It holds up in the pan
With one double bond rather than several, oleic acid is less prone to oxidation than the linoleic acid that dominates ordinary sunflower or corn oil. Extra virgin olive oil is about 10% polyunsaturated by fatty acids on USDA's figures, against about 69% for regular sunflower oil. Our guide to olive oil for frying covers what that means in an everyday pan, and our healthy fats guide sets olive oil beside nuts, seeds and oily fish across every fat type, not only monounsaturated fat.
Getting More Monounsaturated Fat Without Eating More Fat
The practical rule is to swap, not add:
- Make extra virgin olive oil the default dressing and everyday cooking fat in place of butter, ghee or lard.
- Use rapeseed or high-oleic oils where you need a neutral flavour, and keep regular sunflower oil for occasional use.
- Swap a biscuit or pastry for a 30 g handful of almonds, hazelnuts or macadamias.
- Spread avocado on toast instead of butter.
- Add olives to salads and grain bowls in place of cheese now and then.
- Read the "saturates" line on labels: the NHS treats more than 5 g per 100 g as high.
If you have a medical condition, take cholesterol-lowering medication or follow a prescribed diet, speak to your GP or a registered dietitian before changing your fat intake. To choose a bottle that brings the unrefined benefits as well as the oleic acid, our guide to choosing a quality olive oil walks through every label check.
Why Sidr & Stone
The USDA figures in this article describe olive oil in general, not our bottle, and we do not borrow them as our own results. Sidr & Stone does not yet publish a laboratory certificate for its oil's fatty-acid or polyphenol content, so we make no polyphenol claim. What we can tell you is how our extra virgin olive oil is grown and made.
- Single-estate — Sidr & Stone's extra virgin olive oil comes from our own family-owned farm on the plains outside Marrakech, Morocco, and we control every step from tree to bottle.
- Rain-fed — the trees are not irrigated; they take what the season gives.
- Organically grown — no synthetic fertilisers, pesticides or herbicides are used (not yet certified; certification is in progress).
- Single harvest — a small, limited single-harvest batch, picked when the fruit is ready; once it is gone, it is gone until the next harvest.
- Cold-pressed — to protect flavour, aroma and the oil's natural polyphenols.
- Unfiltered extra virgin — minimally processed, so a little natural sediment is normal.
- 100% natural — a single ingredient, olive oil, with nothing added.
- 500ml dark glass with a gold label — packaging that shields the oil from light.
- 10% of profits to charity — a brand-wide commitment.
- Fulfilment in the UK, EU, and US.
We will not tell you Sidr & Stone is the best olive oil — that would be the very kind of claim this article warns against. What we will say is that our oil is single-estate Moroccan, rain-fed, organically grown and cold-pressed: an unrefined monounsaturated fat that tastes of the fruit it came from.
Frequently Asked Questions
What are monounsaturated fats?
Monounsaturated fats are fats made mainly of fatty acids with a single double bond, chiefly oleic acid. They are liquid at room temperature and are found in olive, rapeseed and hazelnut oils, avocados, olives and most nuts.
Is omega-9 the same as monounsaturated fat?
Mostly. Oleic acid, the main monounsaturated fatty acid in food, is an omega-9. But not every monounsaturated fatty acid is omega-9 — palmitoleic acid in macadamias is an omega-7 — and omega-9s are not essential, because the body can make oleic acid.
Which foods are highest in monounsaturated fat?
Oils first: on USDA figures, high-oleic sunflower, hazelnut, high-oleic safflower, olive and avocado oils are all about 74–86% monounsaturated. Among whole foods, macadamias, hazelnuts, pecans and almonds lead, followed by avocados and olives.
Are eggs high in monounsaturated fat?
Not especially. A 50 g egg carries about 1.8 g of monounsaturated fat on USDA's figures — slightly more than its saturated fat, but a small amount, and only about 42% of its fatty acids, below the 45% a label needs to say "high monounsaturated fat".
Is Sidr & Stone olive oil high in monounsaturated fat?
Extra virgin olive oil as a category is about 74% monounsaturated on USDA's figures, and ours is extra virgin olive oil. We have not yet published a laboratory fatty-acid analysis of our own batch, so we do not quote a figure for it.
How much monounsaturated fat should I eat a day?
UK guidance does not set a separate target for monounsaturated fat. It caps saturated fat at 30 g a day for men and 20 g for women and advises replacing some saturated fat with unsaturated fat — so the useful aim is the swap, within your overall energy needs.
Where can I buy Sidr & Stone olive oil?
Our Cold-Pressed Single-Estate Extra Virgin Olive Oil - Marrakech (500ml) is available to pre-order as a limited single-harvest batch from our website, with fulfilment in the UK, EU, and US.
Is olive oil a medicine?
No. Olive oil is a food, not a medicine. It has a long traditional history — including being honoured in the Prophetic Sunnah — and a substantial body of modern research, particularly around polyphenols, cardiovascular health, and the Mediterranean diet pattern. It can be a worthwhile part of a healthy routine, but it does not cure diseases and is not a substitute for medical care. Be cautious of any olive oil marketed with specific disease-cure claims.
Final Thoughts
Monounsaturated fat is easy to define — one double bond, mostly oleic acid — and easy to find in olive oil, nuts, avocados and olives. What it is not is a number to chase on its own. Lard has plenty of it; ordinary sunflower oil has little; the evidence and the law both point to the same thing, which is using monounsaturated fat in place of saturated fat rather than on top of it.
That is why olive oil leads. It is not the very top of the USDA table, but it is the monounsaturated fat most of us cook and dress food with every day, it is mainly oleic acid, and in its extra virgin form it is an unrefined fruit oil with flavour and polyphenols of its own.
Our Cold-Pressed Single-Estate Extra Virgin Olive Oil - Marrakech (500ml) — single-estate, rain-fed and cold-pressed — is available to pre-order now, with fulfilment in the UK, EU, and US.
Our extra virgin olive oil is grown organically on our own single-estate farm on the plains outside Marrakech: we control every step from tree to bottle, and no synthetic pesticides, herbicides or fertilisers are used. It is not yet certified organic — certification is in progress, and we will publish it as soon as it comes through.
References
1. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central entries 748608 (Oil, olive, extra virgin; Foundation), 171413 (Oil, olive, salad or cooking), 172338 (Oil, sunflower, high oleic (70% and over)), 171027 (Oil, safflower, salad or cooking, high oleic), 171427 (Oil, hazelnut), 173573 (Oil, avocado), 172336 (Oil, canola), 171410 (Oil, peanut, salad or cooking), 171401 (Lard), 173410 (Butter, salted), 171025 (Oil, sunflower, linoleic), 171412 (Oil, coconut), 170178 (Nuts, macadamia nuts, raw), 170581 (Nuts, hazelnuts or filberts), 170182 (Nuts, pecans), 170567 (Nuts, almonds), 172470 (Peanut butter, smooth style, without salt), 170162 (Nuts, cashew nuts, raw), 170569 (Nuts, brazilnuts, dried, unblanched), 171705 (Avocados, raw, all commercial varieties), 169094 (Olives, ripe, canned) and 171287 (Egg, whole, raw, fresh); SR Legacy unless stated. Accessed 12 October 2026.
2. NHS. Facts about fat. nhs.uk, accessed 12 October 2026.
3. Regulation (EC) No 1924/2006 on nutrition and health claims made on foods, Annex; Commission Regulation (EU) No 432/2012, Annex (monounsaturated and/or polyunsaturated fatty acids, and olive oil polyphenols entries). legislation.gov.uk, accessed 12 October 2026.
4. Vafeiadou K, Weech M, Altowaijri H, Todd S, Yaqoob P, Jackson KG, Lovegrove JA. (2015). Replacement of saturated with unsaturated fats had no impact on vascular function but beneficial effects on lipid biomarkers, E-selectin, and blood pressure: results from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study. American Journal of Clinical Nutrition, 102(1), 40–48. doi:10.3945/ajcn.114.097089. PMID 26016869.
Disclaimer: This article describes the fat composition of foods using USDA FoodData Central, UK government guidance, EU and UK labelling rules and published research at the time of writing; database values, guidance and regulations may change, and composition varies between foods and harvests, so readers should check current sources. It is general nutritional information, not personalised dietary advice. Olive oil is a food, not a medicine, and is not a substitute for medical treatment of any condition. For any health concern, consult a qualified medical professional.