In Defense of Vitamin A

In the bone health world, vitamin A has a bad reputation. Some studies have suggested that it’s toxic to bones because it increases the activity of the osteoclasts. These are the cells that do the important work of cleaning away old bone. If they get carried away, though, there can be a net loss of bone if they outpace the osteoblasts that are working to build new bone.

But recent research has found that this isn’t actually the fault of vitamin A itself, but of a failed partnership. If there’s a shortage of vitamin D or vitamin K2, then A can’t do its job properly; the three fat-soluble nutrients are meant to work together for bone care. If we absorb too much of one of them, that creates a corresponding need for more of the others. Since a huge percentage of people are deficient in both D and K2, this means that for the bones of some people, taking preformed vitamin A can be detrimental.

Too little vitamin A, though, is also a problem. A deficiency can also cause bone loss, as well as impaired vision, dry eyes, and a pre-disposition to a host of diseases, including cancer. The key is having good nutritional balance.

As for my story, I was able to bring my vitamin D level into a healthy range with supplements. Check. And I added vitamin K2 to my diet by eating natto three times a week. Check. My vitamin A, though, persistently tested low, even though I eat a lot of foods with beta-carotene, which is supposed to convert to vitamin A. What was that about? Why couldn’t I raise my level of vitamin A?

It turns out that many people can’t process beta-carotene much or at all, for a variety of reasons. For some, the problem is a diet lacking the healthy fats needed to stimulate absorption. For others, it may be that they drink too much alcohol, or that they have inadequate bile flow. Or their gut ecology may be out of balance, perhaps because of low stomach acid levels, celiac disease, or parasites. And to complicate the issue, a large percentage of the population were just born with a genetic variation that prevents them from absorbing beta-carotene or converting it into the active form.

So what can we do to get enough vitamin A in our systems? First, get tested to determine whether you’re in the majority who need some more. If you are, then make sure you eat plenty of retinol foods. The top of this list is cod liver. The second, third, and fourth options are other kinds of liver. If this makes you shudder, then you may benefit from taking preformed vitamin A, or retinol, as a supplement. It often comes in tiny capsules made from cod liver oil, but you won’t taste a thing. It’s also available in dry tablets. But since vitamins A, D, and K2 are fat-soluble, which means they can build up in our tissues, it’s important not to overdo them.

And here’s a side note if you’re hoping to see your hundredth birthday: vitamin A sufficiency is now recognized as a key contributing factor to longevity.