Do vegans get enough vitamin A? The question is controversial for two reasons. First of all, plant foods do not contain vitamin A. That is, they don’t contain pre-formed vitamin A. They don’t contain the actual vitamin, in all its eye-health glory.
“WHAT?! But my nutrition book says that carrots, sweet potatoes, cantaloupe, and other fruits and vegetables contain vitamin A.”
I know. So does my go-to book on nutrition. Otherwise a good source of information, the book The World’s Healthiest Foods lists many different plant foods as containing vitamin A. I’m not sure why, since the author seems to be a guy who has done his research.
But the truth is, plant foods do not contain vitamin A. Many of them contain the group of phytonutrients known as the carotenoids. There are fifty, and the human body can convert all into vitamin A. Beta carotene, being the most common carotenoid, is the most well-known.
Which brings us to the second reason that this question of whether vegans get enough vitamin A is controversial: supposedly, some study or other has shown that only three percent of the beta carotene that is consumed gets converted into vitamin A. If this is true, vegans would probably have to eat something like fifty pounds of carrots every day to get the vitamin A their body needs.
Orange skin, anyone?
But I have to question the veracity of the statement, that only three percent of the beta carotene consumed converts to vitamin A. I’ve seen that in several places online, but nobody wants to talk about how scientists reached that conclusion. Likely because they don’t know.
How do the scientists know, anyway? How can they possibly feed a person foods with beta carotene and determine how much of it is getting converted to vitamin A? I suppose they might have the research subjects not consume any animal products for a few months, test their vitamin A levels, then start feeding them beta carotene and testing vitamin A levels every few days.
Oh, no, wait a second. I found it! According to an article on the National Institute of Health, this conclusion was not based on testing blood or liver conversions or anything like that in actual live people. It was a test-tube experiment, involving DNA manipulation, and not done on human subjects at all!
Still, there is the possibility that the three percent conversion figure is correct. If so, that would mean that long-term vegans would be suffering from symptoms of vitamin A deficiency. In that case, we would have to get seriously serious about delving into how vegans get vitamin A.
So let’s delve a little deeper, just in case. Since scurvy occurs as early as three months from developing a severe vitamin C deficiency, and since in Africa the children going blind and dying from severe vitamin A deficiency are infants and toddlers, we can safely assume that symptoms of severe vitamin A would show up within five years of someone adopting a 100% plant-based diet. Maybe ten years, if they had a superior store of vitamin A from animal products when they went vegan, but that would be rare.
So, what are the symptoms of a severe vitamin A deficiency? Night blindness and a condition known as xerophthalmia. Xerophthalmia results from a vitamin A deficiency and leads to an impaired immune system, cancer, and birth defects in babies of mothers who have xerophthalmia.
Eventually, this condition can also lead to total blindness.
So the question is, are long-term vegans suffering these problems? Do vegans get enough vitamin A?
Some are struggling with night blindness. But most are not dealing with xerophthalmia. You can look up any number of people who have been consuming a 100% plant-based diet for more than five years, even more than ten years, and do not have cancer, have had healthy children, and who have not gone blind.
You say, maybe they’re taking a supplement. Some of them likely are. However, many whole-food vegans – especially those of the raw variety – refuse to take supplements of any kind, with the possible exception of vitamin B12. Also, many who do supplement take a plant-based supplement, where the vitamin A that is listed is, in fact, beta carotene.
Let’s look at what vegan Registered Dietatian, Jack Norris, has to say about it. In a blog post, he writes:
When I first got involved in vegan nutrition, vitamin A was considered a non-issue because we assumed most vegans would easily get enough beta-carotene with any sort of varied diet to cover our needs.
But in 2001, the Food and Nutrition Board (FNB) doubled the amount of beta-carotene they said was enough to meet vitamin A needs. According to the FNB, this change was based on “data demonstrating that the vitamin A activity of dietary ß-carotene is one-sixth, rather than one-third, the vitamin activity of purified ß-carotene in oil (1).”
They go on to say:
“This change in bioconversion means that a larger amount of provitamin A carotenoids, and therefore darkly colored, carotene-rich fruits and vegetables, is needed to meet the vitamin A requirement. It also means that in the past, vitamin A intake has been overestimated.”
This change mostly flew under the radar, but it made a significant difference in how easy it would be to get enough beta-carotene.
I recently became more concerned about vitamin A, quite literally, by accident. Early last Fall, I twice got up in the middle of the night and walked straight into my bedroom door that was halfway open, face-first!
Over the previous year or so, I had slacked off on vitamin A, relying only on a bit of shredded carrots on salad and mangoes on most days. In mid-November, I decided I needed to make a real effort to add more yellow vegetables to my diet and started eating sweet potatoes every day. A few weeks later, I realized that I had been having no trouble seeing the bedroom door at night. I wondered if there was a connection to what seemed to be my improved night vision.
In checking out whether it was likely that my apparent change in night vision was possibly caused by eating more beta-carotene, I was reminded that vitamin A metabolism is involved with immune function. When vegans get sick easily, I tell them to think about more zinc or protein, neglecting any concern about vitamin A. (Interestingly, vitamin A metabolism appears to rely on zinc.)
Vitamin A deficiency symptoms begin with night blindness, and if it progresses, can lead to the more severe eye problems of corneal ulcers, scarring, and blindness. Vitamin A is also important for growth and development in infants and children, and for red blood cell formation.
Note two things from this article regarding vegans and vitamin A. First, based on their findings the Food and Nutrition Board did not recommend that vegans begin consuming thirty times more beta carotene than previously believed necessary, but only twice as much.
Second, Jack Norris himself merely added a couple of carrots and some sweet potato in order to cure his night blindness. If it were true that his body only converted three percent of the beta carotene that he consumed into vitamin A, then adding some carrots and sweet potatoes to his diet would not have been enough to cure his night blindness (sweet potatoes, contrary to popular belief, are much lower in beta carotene than are carrots). Or, as I mentioned earlier, the amount of vitamin A we need on a daily basis has been vastly overestimated.
So, whom should you believe? Personally, I think if you consume the equivalent of one or two cups of chopped carrots every day, your body will end up with plenty of vitamin A. But we’re all different.
Ruth Heidrich, who healed herself from cancer more than thirty years ago by going on a whole-foods vegan diet, eats a lot of dark, leafy greens. She also eats some carrot along with other foods with lesser amounts of beta carotene. She is one of the healthiest eighty-somethings in the United States…even though she’s not consuming, per what I’ve heard her say, four carrots a day.
If you want to hedge your bets, or for some reason don’t want to eat so many carrots every day, it’s not illegal to take a supplement. Just be aware that you can overdose on synthetic pre-formed vitamin A, so stick with the dose recommended on the label. Or, to be on the safe side take half a dose every day or every other day to augment the beta carotene in your diet.
You’re in charge of your body. Make the decision that’s right for you.