I get a lot of email asking me about various alternative therapies and supplements. A recurring theme on this blog has been the hyperbolic claims of alternative practitioners and supplement makers, and while I can’t answer every email, I can at least address some of them in the blog. Supplements are often marketed using unsupported health claims to which is appended the Quack Miranda Warning, essentially allowing the makers to say that the pill will have such and such a benefit, while simultaneously denying any responsibility for the claim.  Since the FDA isn’t examining these claims, it’s worth while to ask our own questions.

The latest email concerned a product called CardioFuel. Let’s take a closer look at this stuff.

According to the distributor:

CardioFuel is the most profound energy producing supplement on the market today! It does something like no other can: Increase energy at the most basic metabolic level, by increasing ATP (the biochemical energy unit of transfer) production. More ATP means more energy reserves to overcome chronic disease, beat the competition, and handle the everyday stressors of today’s fast paced world!

So to be taken seriously, there should be evidence that this product: 1) increases ATP, 2) increases “energy reserves”, and 3) helps overcome chronic disease and “the competition”. First, it is not possible to directly measure ATP in a human being under normal clinical conditions, so any claims about this must be an inference from markers of ATP metabolism, or a guess. We’ll see what the literature says about this below. Second, we need an operational definition of “energy reserves”. Does this mean fat stores? Glycogen stores? These things are measurable to an extent.  Finally, we can do a literature search to see if CardioFuel or an acceptable analog has been tested for its effect on relevant outcomes.

First, what is ATP?

ATP is adenosine triphosphate, a biological molecule with many functions, among them the transfer of energy. ATP is produced in several ways, most famously in the Krebs cycle, a complicated biochemical process which premeds are mercilessly forced to memorize. ATP contains three phosphate bonds, and the third bond contains a great deal of energy, energy that the body uses to fuel many biochemical processes. Each molecule of ATP contains a d-ribose moiety, a simple sugar upon which the molecule is built. One of the claims being made by the CardioFuel folks is that if we ingest more d-ribose, we can make more ATP and be more “energetic”.

First, ATP synthesis, like most biochemical processes, is subject to feedback regulation; ATP production and its byproducts feed back to reduce further ATP production. Second, it is not clear to me that simply providing more of this particular substrate would significantly boost ATP production. But with my limited knowledge of biochemistry, it seems like an interesting question to investigate.

CardioFuel claims that its “ATP boosting” properties are  not just from ribose, but also from other molecules such as carnitine and coenzyme Q10.  There is nothing in the published literature that I can find to support these claims.

From my perspective as a physician, I want to see results.  Regardless of what is posited to happen at the cellular level, I want to see outcomes studies supporting the claims that d-ribose, or preferably CardioFuel itself actually does what is claimed, which the marketer further specifies:

I created CardioFuel to help my patients who suffer serious energy-depleting chronic diseases, such as: heart disease (PVD), diabetes, neuromuscular disease, fibromyalgia, lung disease, Chronic Fatigue Syndrome, kidney disease, HIV/AIDS, etc. These diseases deplete ATP, which CardioFuel rapidly replaces, dramatically improving health, vitality, and Quality of Life (QOL).

A PubMed search for “CardioFuel” turned up nothing.  Of the ingredients claimed to boost energy, d-ribose is the one with the most literature—literature which is not favorable.  There are a number of pilot studies looking at d-ribose in exercise.  For example, one study of twelve cyclists found that, “D-ribose supplementation has no impact on anaerobic exercise capacity and metabolic markers after high-intensity cycling exercise.”  A slightly larger study of rowers compared dextrose (d-glucose) with ribose and found that, “…the dextrose group showed significantly more improvement at 8 weeks than the ribose group.”  Another small study found that,” ribose had no effect on performance when taken orally, at the dose suggested by the distributor.”Since I couldn’t find literature specific to CardioFuel, and my literature search failed to find significant support for claims of the ingredients of CardioFuel, I went to the CardioFuel website for further guidance.  Tellingly, there are no references to studies of CardioFuel itself but only for its purported ingredients. There are some chaotic lists of incomplete references.  For example, for coenzyme Q10, some of the references are listed, some just quoted without citation, and there is little data related to the claims of CardioFuel.  The section on “elite athletes” addresses ribose directly, but not with outcomes studies.

I can find no support for the claims made by the sellers of CardioFuel. But under the Dietary Supplement Health and Education Act of 1994 they are allowed to make these claims as long as they use the Quack Miranda Warning. I couldn’t find such a warning on any page of the website so I guess I must assume that all of the claims made by the company are verifiable. I can’t seem to verify them myself, but the data must be somewhere. Right?