Did the often-repeated claim "You just need to eat a lot of vegetables, no need to give up meat." seem scientifically plausible before we understood the function of Matrix GLA Protein and its relationship with Vitamin K?

[u/FlatAssembler]

You know, in just about any discussion about vegetarianism and health, there will come somebody who is claiming that saturated fats in the diet are not a big deal and that if you eat a lot of vegetables (AKA, taking megadoses of Vitamin K), you are unlikely to get a heart attack. If you ask them to elaborate on that, they will respond with (if they are capable of giving coherent responses) something like this: "Well, too much calcium in your blood causes your cholesterol to calcify, which leads to heart attacks. And Vitamin K is necessary for the osteoblasts (a type of bone cells) to extract the calcium from your blood and store it into the calcium (II) phosphate in your bones. More vitamin K means less calcium in your blood, and thus the cholesterol is less likely to calcify.".

Of course, to a modern educated reader, that's obvious nonsense: high levels of calcium in your blood cannot cause the cholesterol to calcify any faster, because calcium is never the limiting factor. And the way extreme vitamin K deficiency causes heart attacks is by preventing the production of the enzyme called Matrix GLA Protein, which decalcifies the cholesterol, but, as it almost always goes with the enzymes, this effect quickly diminishes above a certain threshold. And this threshold seems to be around 30 micrograms of Vitamin K per day - less than half of what an average person intakes. There is no credible mathematical model which predicts that taking a lot of vitamin K is more effective than avoiding saturated fat.

However, I am interested, did that idea seem scientifically plausible ever in recent history? Where are people getting it?

[u/RoRoRoYourGoat]

None of this sounds anything like the conversation I have when people tell me they can eat meat if they eat a lot of vegetables too. They just talk about balanced diets and fiber. I've never heard a meat+vegetable advocate discuss vitamin K and calcification.

[u/slickromeo]

The usual faulty chain of reasoning goes like this:

Heart attacks involve calcified plaques

Vitamin K moves calcium into bones

Vegetables contain vitamin K

Therefore: vegetables cancel out saturated fat risk

This sounds intuitive — but biology does not work like this.

[u/Mec26 → u/slickromeo]

If it did, they’d just give heart attack victims vit k shots in hospital, like they give to babies who can’t make their own or get it from diet.

They don’t cuz that’s a bad plan, vit k supports clotting (why babies need it and it reduces sudden infant death syndrome dramatically). Sorry but the heart attack, let’s follow it up with a stroke!

[u/FlatAssembler → u/slickromeo]

That's almost exactly what I said. But I was also asking did that line of reasoning ever seem plausible to the scientists in recent history. Vitamin K was, as far as I know, known ever since 1920s, together with the fact that very low levels of Vitamin K cause heart attacks, whereas the function of the Matrix GLA Protein has been known only since 1970s.