The most important supplements for vegans are Vitamin B12 and to some extent Vitamin D also.
Vitamin B12 is actually made by bacteria. No animals ( humans or cows or chickens ) can make them.
When cows are given the feed, it comes straight from the farms and they are not sterilized feed.
So, this kind of feed obviously contains so many bacteria.
Not all bacteria are bad ( as we think ). There are many good bacteria also.
These bacteria go into the animal’s intestines and make Vitamin B12 for them.
So, when we consume their meat or their products ( like dairy), we get Vorammoin B12.
But, since we live in a very sterile society, and sterilize all our foods, we lose a lot of helpful bacteria.
And that’s why we become Vitamin B12 deficient when we do not consume meat or dairy products.
And that is why Vegans lack Vitamin B12.
But, to have enough Vitamin B12, it’s not worth taking a risk of eating animals or animal products – like meat and dairy.
The best solution is to take Vitamin B12 supplements.
Of course, small amounts of Vitamin B12 can be obtained from fermented foods – Like
But they all contain very small amounts of Vitamin B12 in them.
So, if one is resistant to taking any kind of supplements ( including Vitamin B12 ), they should increase consumption of the above-mentioned foods, but it will be advisable to get heir Vitamin B12 levels checked regularly.
Same way Vitamin D3 does come from dairy, but it is not naturally present in milk, on the contrary, it gets fortified in the milk.
So, when it comes to Vitamin D3 – Vegans or Non-Vegans, all are equal.
For Vitamin D3 needs, there is no reason to consume dairy.