Toxic Information

Background story

I was reading “Oxygen: The molecule that made the world” by Nick Lane. (It’s a really good book by the way, and I think everyone who has high school level knowledge of chemistry and biology should consider putting it on their reading list. It’s a fun and interesting read.)

In the book, a chapter touched upon the issue of Vitamin C (since it’s an “anti-oxidant”, kinda). Now, you have probably heard of the controversy regarding Vitamin C — Nobel Laureate Linus Pauling famously claimed that supplementation of high doses were beneficial, but for decades since people have found little evidence of such. On Vitamin C, all we know for sure is that it prevents scurvy at a relatively low level of intake, a diet that includes fresh fruits and vegetables is usually enough to ward off scurvy.

What triggered me (pun intended?) to write this rant is when I read how the current Recommended Dietary Allowance (RDA) values were devised. Since the complexity of the subject is important, I’ll quote the text verbatim:

Ironically, the concept of vitamin C as the dietary element that prevents scurvy has hampered our understanding of its positive role in the body. The general approach to how much vitamin C we need to eat each day (the recommended daily allowance or RDA) is derived from this negative stance — the prevention of scurvy — rather than any positive criterion. The amount of vitamin C required to prevent clinical scurvy, in other words to hide any obvious signs of disease, is surprisingly small. A series of studies on the inmates of Iowa jails in the 1960s showed that only about 10 milligrams a day are required to abolish the signs and symptoms of scurvy. When the dose is raised to about 60 milligrams a day, we begin to excrete vitamin C in our urine, implying that the excess is superfluous to requirements. The notion that our body pool is saturated by about 60 milligrams a day is supported by the rate of breakdown of vitamin C: the Iowa studies suggested that breakdown products are excreted in the urine at a rate of about 60 milligrams each day.

These three factors, then — prevention of scurvy with a margin for error, excretion of vitamin C, and excretion of breakdown products — form the basis of the long-standing RDA of 60 milligrams vitamin C daily.

Although this analysis sounds like a closed case, it is in reality misleadingly simplistic. The case is confounded by both practical and conceptual difficulties.

These were scrutinized during the 1990s by Mark Levine, of the NIH. Levine had been a member of the panel convened by the NIH to review Cameron’s 25 case studies in 1989, and has since done more than anyone to bridge the gap between mainstream medicine and the advocates of vitamin C.

Besides querying the accuracy of the early measurements of vitamin C and its breakdown products, which were carried out using insensitive and non-specific tests, Levine questioned the assumptions underlying each of the three factors used to estimate the RDA. First, he said, the amount of vitamin C required to prevent scurvy may be much less than the ideal intake for maintaining bodily functions. We do not know how much less. Second, the threshold of urinary secretion may or may not correspond to the saturation of body pools — it does for some substances and doesn’t for others. For vitamin C, we do not know. Third, the rate of breakdown of vitamin C depends on a variety of factors, including the size of the dose consumed. High doses are broken down faster than low doses, perhaps because the body has less need to conserve a precious resource. This means that estimates of breakdown based on low doses (such as 30 or 60 milli-grams) may be misleading. Thus, Levine stripped away the conceptual basis underpinning the current RDA of vitamin C.

Far from being merely critical, Levine worked up his own recommendations for a rational daily dose of vitamin C, based on the ideal amount required for known reactions, and the saturation of blood levels and other body pools. For the impatient, let me say immediately that he recommends 200 milligrams daily for healthy individuals; that doses above 400 milligrams have no evident value; and that doses of more than 1 gram may not be safe, as they can provoke diarrhoea and induce the growth of kidney stones. Five portions of fruit and vegetables each day corresponds to a daily intake of between 200 and 400 milligrams of vitamin C, so given a sensible diet there is no need for supplementary vitamin C. We shall see that there are other good reasons for not relying on supplemental vitamins. On the other hand, the RDA of 60 milligrams (raised to 90 milligrams in the United States in April 2000) is, according to Levine, too low. To understand his reasoning, and especially the wider ramifications in terms of antioxidant function, we need to look in more detail at what vitamin C actually does in the body.

Over-simplified information

Given the wall of text above explaining nuances as to how much Vitamin C we need, how are we, laypeople without a PhD in biochemistry or nutrition, supposed to interpret “the RDA of Vitamin C is 90mg”?

The more I thought of it, the more I realized that the watered-down, simplified recommendation of “90mg per day” is in fact, not actionable. I cannot reliably depend on this fact to make decisions. So many questions are unanswered, even assuming the 90mg number is accurate on average - If my usual intake falls short, how bad are the consequences? If I go for a couple days without sufficient Vitamin C, how long will it take for bad things to occur? Should I take Vitamin C supplements to make up for the deficiency?

A single numeric figure is simply not enough for anyone to make informed, correct decisions.

One could argue that the general public is fundamentally incapable of understanding the detailed reasoning that led to the final recommendation, so only the conclusion is communicated in the form of RDA values, and those more intellectually inclined should do their own research or consult a professional.

But given the controversy (which AFAICT is still ongoing) with Vitamin C and its multifaceted functions in our body’s biochemistry, I’m not sure even a professional in the field could give good (and consistent) answers beyond the common sensical advice — eat healthy with lots of quality fresh food and you’ll be fine.

Sure, that’s good advice, but the issue is we already knew that. I mean, we knew fresh food was good for you before we even learned about Vitamin C and started giving out advice in the form of RDAs. We (many of us, at least) have access to hundreds of years of culinary traditions and folk wisdom that told us what we need to eat to stay healthy. (It surely is not “burger and fries and coke, oh and add 90mg of Vitamin C supplements.”)

Misleading, unactionable information is toxic

I don’t think of myself as an “anti-science” kind of person. But I do often think that public communication in science is very problematic, and RDAs is yet another instance of such.

When public health institutions, armed with results from scientific research, authoritatively tell the public that “you should have 90mg of Vitamin C every day”, the general public can actually do very little with this information: for those eating a healthy diet that already meets the requirements, do they have to change? For those subsisting on fast food and soda, do they really have to change their diet, or are supplements enough? For those wanting to optimize their health, what should they do?

Worse, given the social context in which these RDAs are issued, I think the actual effect was to reassure people (especially those living in low socioeconomic conditions) that their poor diet of preprocessed junk food is fine as long as they take a couple pills to make up for the deficiency. (Which isn’t totally wrong, but it isn’t right either.)

If information misleads a reasonable person to come to a wrong conclusion, I think the communication has failed. If it requires one to independently look up the latest research or consult a professional, I think the communication has failed. If it tends to displace valuable folk wisdom without demonstrating substantial benefits in its place, I think the communication has failed.

And I think given the tendency of science to go overboard with reductionism, prescribing the daily intake of chemicals invariably lead to flawed ideas like Soylent — in the best case it only works as a convenient supplement for the average person, but in the worst case, we might be missing some essential trace nutrient that we’d only find out after prolonged exclusive diet of synthetic foods.

And what’s wrong with the idea of consuming local, fresh foods prepared with traditional culinary methods? The RDA makes it sound as if meeting those requirements was all is needed for a healthy diet, but in most cases following advice from classic folk wisdom is sufficient and necessary, while arguably the RDA is neither.

So I would say that such information, in the context of public communication, is toxic.

It’s not enough that information is “technically true (even though you need to have a PhD to understand its nuanced)”. It shouldn’t mislead and crowd out other more valuable bits of information in the public space.

And we have a lot of toxic information out there in the name of Science.