Few nutrition topics have swung as much as dietary fat. Saturated fat was condemned, then partly rehabilitated in popular coverage, then re-examined. Traditional fats were abandoned for seed oils, and are now being promoted back.
The evidence supports a more moderate position than any of the popular framings.
What ghee is
Butter with water and milk solids removed through heating. What remains is essentially pure butterfat.
Removing the milk solids raises the smoke point substantially compared with butter and extends shelf life considerably, which is why it developed in warm climates without refrigeration.
Nutritionally it's high in saturated fat, contains fat-soluble vitamins, and includes small amounts of butyrate and conjugated linoleic acid, which are frequently cited in promotional claims. The quantities involved are small relative to what studies of those compounds have used.
The saturated fat question
The core of the argument, and the honest position is that it remains contested.
Major health bodies continue to recommend limiting saturated fat intake, based on its effect on LDL cholesterol and on trials substituting unsaturated for saturated fat.
Critics point to observational studies finding weaker associations between saturated fat intake and cardiovascular outcomes than the guidelines imply, and argue that the effect depends heavily on what replaces it.
That last point has substantial support. Replacing saturated fat with polyunsaturated fat is associated with reduced cardiovascular risk in the trial evidence. Replacing it with refined carbohydrate is not, and may be worse.
Which means the question is not simply whether saturated fat is harmful but what it's being compared against — and a great deal of confused public discussion follows from ignoring that.
There's also increasing attention to food matrix effects: saturated fat in cheese and in processed meat appear to have different associations, suggesting the whole food matters rather than the isolated nutrient.
The seed oil argument
A vigorous online debate with more heat than evidence.
The claims typically involve omega-6 fatty acids being inflammatory, and oxidation products formed during processing or heating.
The evidence for harm from omega-6 intake at typical levels is weak. Trials substituting polyunsaturated for saturated fat have generally shown favourable effects on cardiovascular outcomes, and major reviews have not supported the claim that linoleic acid intake increases inflammatory markers in humans.
The oxidation concern is more substantive in one respect: repeatedly heated oils, particularly at high temperatures over long periods as in commercial deep frying, do form degradation products, and there's reasonable concern about those.
That's an argument about how oils are used rather than about the oils themselves, and it applies to any fat heated repeatedly.
Smoke points, which matter practically
The temperature at which a fat begins to break down, producing off flavours and degradation products.
Refined oils generally have higher smoke points than unrefined, because the compounds that smoke are largely removed in refining.
Ghee has a high smoke point, making it suitable for high-heat cooking. Extra virgin olive oil has a lower one and is better suited to moderate heat and finishing, though it's more heat-stable than the smoke point alone suggests due to its antioxidant content.
Cold-pressed and unrefined oils generally shouldn't be used for high-heat frying — their virtues are flavour and minor components that heat destroys anyway.
The practical rule: refined high-smoke-point oils for frying, flavourful unrefined oils for lower heat and finishing.
What actually matters more
Several things carry more weight than which fat you choose.
Total quantity. All fats are energy dense. The amount used matters more for overall diet than the type.
What's being fried. Deep-fried food is a concern largely because of what it is and how much is eaten, more than because of the specific oil.
Reusing oil. Repeatedly heated oil accumulates degradation products. Domestic reuse a small number of times, with straining and proper storage, is different from commercial practice of heating the same oil for days.
The overall dietary pattern. Studies of dietary patterns consistently find stronger associations with outcomes than studies of individual nutrients. A diet high in vegetables, pulses, whole grains and fish is associated with good outcomes across a range of fat compositions.
A reasonable position
Use a variety of fats rather than exclusively one. Different fats have different properties and there's no evidence that any single one should dominate.
Match the fat to the cooking method — high smoke point for high heat, flavourful unrefined for finishing.
Ghee in moderate quantities is fine, tastes excellent, and is culturally appropriate to a great many dishes where a substitute is worse. It's also high in saturated fat and worth using with that in mind rather than as a health food.
And be sceptical of any framing that identifies a single ingredient as the cause of population-level health problems. Those problems have many contributors and the search for a single villain has misled repeatedly.
General information only. Anyone with a cardiovascular condition or specific dietary requirements should consult a qualified healthcare professional.