Why does it have to be supplementation?
Nutrition science is mostly unreliable because it is difficult to study, is very limited and progress is slow. The supplementation industry capitalizes on this ill-reported junk science.
For many years, vitamin D2 was sold as supplementation. Now it is well-known that D2 is not bioavailable to humans. Similarly, it is well-known now that even D3 is mostly useless without K2. Now, some D3 supplements come with K2. Who knows what we'll find in the future?
Even more ridiculous is iron. The iron in spinach is basically rust. It is not bioavailable to humans. Not only that, it induces oxidative stress in humans. Ever heard you need anti-oxidants? You do, if you've been eating spinach or cereal fortified with rust or supplements with such iron. Our body needs a specific organic compound of iron: heme. You can't just swallow a nail and get iron from it.
Vitamin A, D, E, K are all available in animal fat, in exactly the forms we can readily absorb. Animal fat has been a crucial part of diet for every human culture forever. There has never been a single exception... until recently when junk science and industry PR started selling seed oil as a "healthy" replacement. As a result, a large portion of population is deficient in these vital nutrients.
Seed oil is highly problematic because... it's seed. Not only does it have no nutrients, plants don't want you to eat their seed. That is the one thing plants don't want you to eat, more than anything else. That is why they pack it with the most dangerous toxins they can come up with.
Nutrition science is hard but nutrition is easy. Just eat what humans have been eating for thousands of years.