The Daily Harvest mystery—a cause at last?

Thanks to Bill Marler for keeping us all up to date on the Daily Harvest saga.  He keeps up with the literature and writes, Is the Tara mystery closer to being solved?

My most recent post on this mystery was almost a year ago.

To review: Daily Harvest is a company that makes and ships preprepared vegan frozen meals, one of which, French Lentil + Leek Crumbles, has been recalled after several hundred people who ate it developed serious problems with their livers and gall bladders.

This was no trivial incident.  The FDA reported “As of 10/18/2022, there were 393 adverse illness reports in 39 states with 133 hospitalization and 0 deaths.”  But it could not detrmine the specific cause or route of contamination.

My post had breaking news:

The ingredient that caused the illnesses among people who consumed Daily Harvest’s French Lentil + Leek Crumbles has been identified, sort of.  As suspected, it’s the tara flour.  But what’s the toxin in the tara flour?  That, we still don’t know.

Now we have a new study: Is Baikiain in Tara Flour a Causative Agent for the Adverse Events Associated with the Recalled Frozen French Lentil & Leek Crumbles Food Product? A Working Hypothesis. 

In summary, the results of these initial studies support a working hypothesis that the adverse events reported by individuals consuming the Daily Harvest Crumbles product originate from the tara flour ingredient and are due, at least in part, to high levels of nonprotein amino acids (e.g., baikiain). It is further hypothesized that in vivo metabolism of metabolically unstable baikiain results in a toxic metabolite(s) that depletes glutathione and/or is an irreversible enzyme inhibitor (for L-pipecolate oxidase), resulting in adverse events which are dependent on the dose consumed and potentially exacerbated for individuals that have specific genetic predispositions.

Baikiain, which I had never heard of, is an analog of the amino acid proline.  In bacteria, it catalyzes proline destruction.  If it does this in humans, it also might account for the liver toxicity experienced by people who ate the Daily Harvest frozen meals containing tara.

The authors of the tara flour study identified baikiain in the flour.  They gave baikiain to mice, who did not fare well with it.

The hypothesis here is that some people are more susceptible to the toxic effects of baikiain than others.  The French Lentil + Leek Crumbles were sent to 26,000 customers, of which 400 or so got sick, more than 100 of them badly enough to have to be hospitalized; some required surgery.

The lesson here is that food ingredients need better testing.   Whoever makes tara must consider it GRAS (generally recognized as safe) for human consumption.

As Tom Neltner writes,

Tara flour is yet another example of how FDA’s GRAS program is broken—putting the health of Americans at unnecessary risk. FDA should use its big food reboot to fix the program so that we can have confidence in the safety of our food. The agency should also work with members of Congress who have introduced bills intended to fix GRAS and to have FDA reevaluate old food safety decisions in light of new science.

Amen to that.