Choice of statistical framework colors answer to question of whether supplements actually work

The dietary supplement category is entering its 25th year.  Unfettered access to products to support consumers’ optimal health—that has been a foundational principle since the category was created by the Dietary Supplement Health and Education Act in October 1994. 

A category which once hovered round $5 billion in sales in the US now tops $40 billion, accounting for more than eightfold growth. The population of the United States rose from 263 million to about 327 million during the same time frame.

So it’s obvious that dietary supplements are gaining ever greater market penetration. With more Americans using these products every year, are they getting correspondingly healthier?

Critics contend that based on population-based statistics, that’s a difficult case to make. Certain statistics look promising, while many others paint a dismal picture.

By law, dietary supplements cannot claim to diagnose, treat, prevent or cure any illness.  That’s a given.  But some might argue that if we are to measure these effects in a population-based or epidemiological way, what other tools are there, other than to look long term disease incidence trends?  For example, a supplement that claims to be ‘cardioprotective’ might be marketed in a compliant fashion by not claiming to prevent cardiovascular disease.  But if it is doing anything at all, shouldn’t this show up in the CVD statistics in some way?

Large scale statistics don’t support case

If we look at these large scale, population-wide statistical categories, the numbers generally aren’t promising for supporting the efficacy of dietary supplements.

In one bright area, while cardiovascular disease is still the No. 1 killer of both men and women in the United States, accounting for one in four deaths, the trend line on this disease category is positive.  According to the Centers for Disease Control, death from cardiovascular disease has been steadily declining, with cancer predicted to become the No. 1 killer by 2020​​.

Dietary supplements that address CVD risk, such as omega-3s, can perhaps take part of the credit here.  But one could argue that whatever contribution those night have made could very likely have been swamped by the steady decline in smoking, which is the No. 1 risk factor.  According to CDC, in 1965 42.4% of US adults were regular smokers.  The figure for 2016 was 16.8%.

For other major public health areas of concern, the news is uniformly grim.  Obesity rates continue to climb​​, as do the rates for all of the attendant conditions.  In 2016, Colorado, the thinnest (or perhaps better put, least fat) state in the nation had an adult obesity rate of 22.6%.  In West Virginia, now the fattest state, 38.1% of adults were classified as obese.

For diabetes, which follows on the heels of obesity, the trend lines are also up.  A recent CDC report found that s of 2015, 30.3 million Americans—9.4% of the US population—have diabetes. Another 84.1 million have prediabetes.  In 1994, less than 3% of the US population had diagnosed diabetes.

The rate of diabetes had steadily risen from less about 0.5% of the population in 1958 to the 1994 figure.  Then the rate of increase began to accelerate, and has shown no signs of slowing down.

Lifestyle factors

Many of these diseases are related to lifestyle factors, and a number of statistics would support that case. Data from the 2011-2012 NHANES survey showed that more than 34% of respondents ate at least some fast food, and about 23% of them got more than 25% of their total caloric intake from this source​​. According to the Pew Research Center, more than 50 million Americans eat fast food every day​​.  While some fast food manufacturers have attempted to include ‘healthy’ alternatives in their menus, these food sources are generally heavy on saturated fat, simple sugars and salt and have little in the way of vitamins, minerals, fiber or other nutrients.

So, could critics who say there is little evidence for the efficacy of dietary supplements actually be asking these products to play the Dutch boy sticking its finger against a dike overtopped by a Hurricane Katrina of bad habits?

Evidence for efficacy among those who actually use supplements

Among dedicated dietary supplement users, there are statistics that look good. A report released by the Council for Responsible Nutrition in 2015 quantified the potential health care cost savings that could be attributed to dietary supplements.   The report looked at the impact of eight different dietary supplement regimes for individuals aged 55 and older.  The report, which was put together by consulting firm Frost & Sullivan at CRN’s behest, found that savings could range from hundreds of millions to several billion dollars, depending on the supplement intervention​​.

A study done by noted nutrition researcher Prof. Jeffrey Blumberg, PhD, found that use of multivitamin and mineral supplements could almost entirely eliminate the nutrient shortfalls common in American diets​​.  While critics of dietary supplements often argue that consumers should get all of the nutrients they need through the diet, these same critics know that few actually do so. Blumberg and his fellow researchers found that this category of supplements could be a significant contributor to the ‘nutritional well being’ of user.

Wholesale dismissal of data

There is a wealth of additional evidence for the effects of dietary supplements. Much of this data comes from admittedly smaller scale studies conducted by the manufacturers themselves.  Critics of the category tend to dismiss this kind of information out of hand, assuming bias has tainted the researchers’ work. 

This could true in some cases.  But to on one hand decry the paucity of evidence for the effects of dietary supplements while at the same time dismissing as a matter of course all of the work done by manufacturers to try to verify those same effects seems to me to be a view based on dogma and prejudice, not on any sort of scientific rigor. 

So how to make sense of this conundrum? It seems to me to be a case of finding what you are looking for.  There are broad-based statistics out there that would bolster the view that supplements have contributed little to the overall health of Americans in the 25 years that the category has existed.  But other, more focused data sets support the benefits of these products.  When picking your poison, why not choose an alternative that’s relatively cheap, offers significant potential benefits and very little if anything in the way of risk?