Synopsis: Vitamins are essential to our health, and most of those we need we can get through our diets. Many foods are fortified today. Standards for dietary minimums help prevent deficiency diseases, but little is known about whether it’s possible to consume too many vitamins.

Host: Reed Pence. Guests: Catherine Price, author, Vitamania: Our Obsessive Quest for Nutritional Perfection; Dr. Valerie Tarasuck, Professor of Nutritional Sciences, University of Toronto; Dr. Mara Vitolins, Professor of Epidemiology and Prevention, Wake Forest University Baptist Medical Center Links for more information:

Too Many Vitamins?


Reed Pence: Just about everyone knows that vitamins are essential in our diets. The body can’t make them, and you never know if the foods we eat have enough, so a lot of people take a vitamin supplement every day just to be sure. But most people know next to nothing about vitamins, according to journalist Catherine Price, author of the book, Vitamania: Our Obsessive Quest For Nutritional Perfection.

Catherine Price: Just because we don’t really know how much we need, or what vitamins can actually do, we’re always looking to nutritional scientists, or the media, or someone to tell us this perfect recipe for health in terms of what supplements we could take, or what we should be eating. And what we don’t really realize, and what I didn’t fully realize before I started my process of writing this book, is that there is a lot of questions that are still unanswered. So, if we’re confused, it’s in part because the experts are also confused.

Reed Pence: What experts do know about vitamins has mostly to do with deficiency. We know the diseases that can result when we don’t get enough vitamins. For example, Price says around the world, as many as a half million children go blind every year as a result of vitamin A deficiency, and many of those children will die. But those kinds of deficiencies are rare in the developed world.

Valerie Tarasuk: We don’t have very much evidence of frank vitamin deficiencies in North America because we’re, as a whole, we’re an affluent society, but also where there were particular issues in our population, because there was insufficiency of a particular vitamin, measures were taken to make sure that people got them.

Reed Pence: That’s Dr. Valarie Tarasuk, Professor of Nutritional Sciences at the University of Toronto.

Valerie Tarasuk: If we look way back in time, we could find evidence of scurvy or pellagra or different kinds of diseases that were associated with insufficient vitamins. But overtime a lot of that has been addressed through things like food fortification. So, if you take the example of flour products that have niacin riboflavin and thiamin added to them, you know, added back after processing, the idea being that you’re putting nutrients back in the system that our body needs, and milling of flour takes them out so we put them back in artificially but that’s important in warding off inadequacies related to those nutrients.

Reed Pence: Deficiencies are the main reason behind the U.S.’ RDA’s for vitamins–the recommended dietary allowance we’re supposed to consume every day. But while we’re so concerned about ensuring against deficiencies we know about, we know a lot less about the effect of consuming huge amounts of vitamins. Price says today that’s becoming more and more common.

Catherine Price: We kind of have two things going on in this country, where you have some people whose diets are so poor that their not eating foods that naturally contain vitamins and their not eating many foods to which synthetic vitamins have been added, and they might actually be at risk of moderate vitamin and micronutrient deficiencies. But then on the flip side, you have people who are super health conscious who are really attracted to things like vitamin waters or sports bars. Those products often have vitamins way in excess of what anyone thinks we actually need. Those people can be getting many times the recommended dietary allowances and though there is this category of people who tend to believe that if a little bit is necessary than a lot must be great and that’s not necessarily true for anything, vitamins included.

Valerie Tarasuk: The science on how much is too much for nutrients is very much a science in its infancy. You think about the history of nutritional sciences we have spent the decades or the centuries that this branch of science has been in existence the preoccupation has been with figuring out how much people need to be healthy. So, that’s what’s happened, right, is we’ve identified vitamins and minerals as essential nutrients and then tried to figure out what are the requirements that people have to optimize health with those nutrients so that’s been the focus. And now the question of well how much b6 can you take before it gets you sick or how much vitamin A can you do or how much vitamin C or how much calcium. Those questions are new questions for the most part and they’re new questions that we’re not that well prepared to answer.

Reed Pence: However, Price says we know that a few vitamins are dangerous in large amounts.

Catherine Price: The ones that cause the most concern would be the fat soluble ones meaning that they dissolve in fat and therefore get stored in our body tissues and are excreted as easily as the water soluble ones. And those are A, D, E and K. And of those, A is the most concerning in terms of acute toxicity, because it can have very bad even fatal effects in terms of your liver if you overdose on it even in the short term. It would take an awful lot, I mean I don’t think you could do it from food, you’d have to do that through supplements, but you don’t wanna be overdosing on vitamin A. And then you have issues with vitamins like D that regulate particular functions in the body so in the case of D it’s role in bone health and in calcium absorption. You can’t absorb calcium without vitamin D, which means it’s really essential in order to have strong bones, but if you were to take large amounts of D over time, you might run the risk of absorbing too much calcium. And if your body has too much calcium it can start putting that calcium in places you really don’t want calcium, like in your kidneys or in your arteries.

Reed Pence: However, we have a lot less information about water-soluble vitamins, like vitamin C and the eight B-vitamins. One good example is vitamin B3–niacin. Tarasuk says it’s very hard to get huge amounts of niacin from natural foods.

Valerie Tarasuk: Mushrooms are a very good source of niacin, but you’d never eat so many mushrooms that you would, you know, have a huge, huge dose of niacin. So we don’t really have a lot of data on how much is too much and what happens if you take too much. Now that we’re into this new era where we have a lot of people taking vitamin and mineral supplements and on top of that consuming fortified cereals and other fortified foods, and now this new product line of beverages that are highly fortified, there’s the potential to consume very, very large amounts of these nutrients and to consume them in ways that we you don’t even know your getting them.

Reed Pence: So Tarasuk says we’re conducting sort of a natural experiment right now. And who knows what the answer will be?

Valerie Tarasuk: Our populations are being exposed or some parts of our population, the consumers of these products are being exposed to extraordinarily high levels of nutrients levels that cannot be achieved through natural sources of those nutrients. Are they harmful? Well we don’t know. We don’t have much data to say how much can you take on a chronic basis before it starts to interfere with your health. The nutrients that are being added to the products that we looked at are primarily water-soluble nutrients, so vitamin C, the B vitamins. Historically water-soluble vitamins have been thought of as safe because if you take too much of them you’ll just urinate them out. Worst-case scenario, you’d have extensive urine but they wouldn’t have done you any harm. Is that true if you take huge doses chronically? We don’t know that. You know is there a point where eventually some of these nutrients will start to cause problems it’s possible.

Reed Pence: And even if all those vitamins don’t do any harm, Tarasuk says researchers are pretty sure they don’t do any good. Even so, food makers see vitamins as a big selling point. And there’s really nobody to stop them.

Valerie Tarasuk: There’s no way out of it. Nutrient enhancements of food helps to sell foods, so I think we’ve seen for some time particular kinds of food manufacturers really emphasizing the nutrient content. So you can find a box of something that says it contains ten essential vitamins and minerals and it’s a sales pitch. There’s no question, but as the practice is getting more and more widespread, we’ve gotta step back and ask the question: is that a good idea?

Mara Vitolins: I think a little bit of enforcement might be nice for a population that very little work has been done to actually look and say, “OK, this person is getting over what they need and how do we correct that?”

Reed Pence: That’s Dr. Mara Vitolins, Professor of Epidemiology and Prevention at the Wake Forest University Baptist Medical Center.

Mara Vitolins: It’s just the manufacturers deciding that it’s a way to market their product and not to say that they are trying to do harm in any way but it’s not the same as this mandatory, where they had a science behind this is a population that needs to get this particular nutrient or vitamin. So, we were more concerned about drawing attention to the fact that there needs to be more oversight.

Reed Pence: Without somebody looking over their shoulder, some manufacturers seem to have gone vitamin crazy. Tarasuk’s study in the journal Applied Physiology, Nutrition And Metabolism looked at 46 varieties of supplemented water and similar drinks.

Valerie Tarasuk: One of the things that is worrisome to me about our findings with respects to these beverages, to find beverages with two, three, five even ten times as much of a particular nutrient then the daily requirement is, let’s put it that way, to find beverages containing several times the daily requirement of an adult male, who would have for the most part with these nutrients the highest requirement in the population. What’s the point? The requirement has been set at a level that we would say would optimize health so far as the science has evolved to understand the role of that nutrient in the body. So, to pick up a can of something that contains five times that amount, well, why? And the downside of it is that the consumer can’t know that it’s a nutrient that they probably won’t stand to benefit from.

Reed Pence: If only a few products we consume in a given day were fortified, we might be able to dismiss it as harmless. But as more and more products come packed with vitamins, Vitolins worries that we’ll go over the line and never know it.

Mara Vitolins: A lot of people could be experiencing toxicities at varying ranges but they really don’t ever connect it to being say “Well maybe I went a thousand times over my daily needs for vitamin E because I consumed a hundred percent of that nutrient in my cereal and then I consumed fifty additional percentile units in my vitamin drink.” So people don’t link toxicities to their foods or their supplements necessarily.

Valerie Tarasuk: When we look at population survey data, what we find is that people that take supplements tend to be people who in their diets have higher levels of vitamins and minerals typically than people who don’t take supplements. And we did a study a few years ago looking at data from the United States where we found that people who eat fortified foods were also more likely to take vitamin and mineral supplements. So, it seems like it’s not the like people who choose these things are doing it as a way to compensate for a really sub optimal dietary intake. If anything, all of the choices they are making in the course of the day as to what they put it their mouth are driven by, I guess, a desire to optimize or to maximize their vitamin intake but then they end up with very high levels.

Reed Pence: Experts say there’s also another risk of a diet full of fortified foods–we may think they allow us to live on nothing but fortified junk foods.

Mara Vitolins: People will say well, I don’t need to eat a healthy diet because I can have that supplemented food and it gives me the same thing, right? Well, unfortunately that is not the case, and you’re fooling yourself into potentially then creating nutrient deficiencies. Like you can have any type of food you want but when you say I’m gonna eat Twinkies every single day because they are nutrient fortified, those Twinkies don’t have everything in them, because there are a lot of nutrients in healthy foods that haven’t even been really categorized you know there are lignin’s, there’s fibers there are all these really healthy there not considered vitamins they are components of that food that are beneficial to our health.

Reed Pence: So if you want some vitamin C, Vitolins says, eat an orange rather than popping a vitamin pill. You’ll get all kinds of other natural substances that are good for you, as well, and you won’t have to worry about vitamin overload. You can find out more about Catherine Price’s book, Vitamania, on her website, Catherine-with-a-c-dash-price-dot-com. Our shows are always available on iTunes or in our archives at I’m Reed Pence.

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