Yes there is.

You can use rancid oil, seed oil, high and long temperatures on polyunsaturaded oils etc. All very unhealthy. Not sure what Japs use though.

▲ mitb6 3 days ago | parent | next [-]

The two most common oils in Japan are canola and soybean, and that's also historically been the case, not a modern change. They definitely do not believe there's anything wrong with seed oils.

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sfjailbird 3 days ago | parent [-]

> The two most common oils in Japan are canola and soybean, and that's also historically been the case

Umm, canola oil has only been available since the 70s. Even rapeseed oil has only been used since the 50s (it is toxic and unpalatable without modern industrial processing, as are many seed oils).

	▲	mitb6 2 days ago \| parent [-]
		Rapeseed oil has been used for cooking in Japan for hundreds of year. The 1950s saw a shift to non domestic production. https://www.tokyofoundation.org/research/detail.php?id=241 I shouldn't have used canola to refer to both. Mustard oil is traditional and still very common cooking oil in South Asia that is even higher in erucic acid than rapeseed. People have used high erucic acid seed as good for a long time.

▲ adamors 3 days ago | parent | prev | next [-]

Seed oils being unhealthy is a recent meme I keep seeing, besides health influencers talking constantly about it, the science just isn’t there.

▲ majkinetor 3 days ago | parent [-]

It's not recent at all, it's there for decades.

Polyfats are unstable by definition, so when you cook with them, they go rancid pretty fast. That is all very well known.

Besides, seed oils usually produce imbalance of w-3 vs w-6 fatty acids which is also deemed to lead to pro-inflamation effects.

This is all very well known and not a hype. Here is a review from 20 years ago:

https://www.sciencedirect.com/science/article/abs/pii/S09523...

▲ throwaway2037 a day ago | parent | next [-]

    > they go rancid pretty fast

How fast is "pretty fast"? I assume that most restaurants change their fryer oil at a max once per week. And after cooking, the (underlying) food is more likely to spoil before the oil on the food going rancid.

	▲	majkinetor 20 hours ago \| parent [-]
		You should assume the worst. Even if oils are not smelly, they can be spoiled and nobody will give a damn at the restaurant. Fast like you use it once or twice, it goes rancid. I witnessed restaurants in the Meditterian that keep oils on the tables for salads, and they are rancid due to hot temperatures. Cook on coconut oil or palm oil, they are the most stable ones. If you go with plant oils, use olive oil as it seets in between poly and saturated oils.

▲ comice 3 days ago | parent | prev [-]

it's definitely increased recently. despite it being at best inconslusive and at worse, false.

https://www.bbc.co.uk/future/article/20250530-are-seed-oils-...

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rsynnott 3 days ago | parent [-]

Huh, I actually thought this particular piece of woo had mostly died out at this point; haven't heard much about it for a few years.

I'd vaguely assumed that it was bored anti vaxers looking for a new Big Bad, but apparently it was Joe Rogan in 2020. Per Google Trends, it seems to have peaked early 2025, which is _much_ later than I thought. Maybe this is a consequence of dumping twitter; I'm missing out on important Oil Discourse.

	▲	majkinetor 3 days ago \| parent [-]
		So what? Some celebrity popularizes decades old good science, and that somehow makes it less valid or untrue ?

▲ throwaway2037 a day ago | parent | prev [-]

Well, if you are going to stay open for long, you had better not use rancid oil! Let's ignore that concern for now, as it generally applies to all food products.

"seed oil" -- What is this nonsense that I keep hearing about on social media? Literally, RFK Jr. (US Secretary of Health) says (amoung other crazy things) that seed oils are "poisoning Americans". Is there any peer-reviewed science behind this "seed oil is bad for you" movement? I have not seen it. Also, Japan uses a wide variety of cooking oil. Probably, olive oil is the least used (only in southern European restaurants). I guess that soybean, canola, peanut, cotton seed, rice bran, and sesame seed oil are the most common oils here -- pretty similar to most of the highly developed world (except rice bran and sesame seed).

Google tells me that soybean, canola, peanut, cotton seed, and sesame seed oil are all considered "seed oils".

"high and long temperatures on polyunsaturaded oils": Japan eats more fried food that people realise, but the portion size is quite small. As I understand, to fry food, you need to have a pool of it that is constantly heated to cooking temperature. That seems to qualify as "high and long temperatures". In fact, wouldn't all fried food suffer from the same? I don't understand the science behind this comment. Can you explain it to me like I'm five? (Other people may be interested to learn more.)

Final small thing: It is best to avoid the term "Japs" in English. It has a historical discriminatory meaning in the United States.

	▲	majkinetor 20 hours ago \| parent [-]
		Who cares about RFK. Even if person X talks nonsence most of the time you can't use that as anrgument for every single thing he says. The toxicity depends on temperature and length of time. So yes. Not all fried food suffer, as saturated fats are stable. Coconut oil or palm oil. For ELI5 you ask AI.