RE: [RC] flax seed question/thyroid? - Susan E. Garlinghouse, DVM
>Hi all, I'm hoping
Susan G. or Heidi or any other person that might have an answer to this
question. >I used to think flax seed was good in
most cases, but something I read this weeked disturbed me. >Had to do with the fact that flax had
the potential of thyroid inhibition. >Is this possibly true? For humans
and or horses? >I'm holding off on flax until I'm
satisfied it is still okay to give. I would appreciate some
reassurance as I know it is widely feed to horses as well as human.
Flax is a minor source of some goitrogenic
compounds, which potentially might be an issue in hypothyroid humans---on that
point, I really don’t know, as humans are a pretty boring species that in
any case, I’m not licensed to treat medically, and thus tend to ignore.<g>
However, almost any polyunsaturated oil is also a source of the same
goitrogens, including soy, canola, corn oil, etc. So I tend to be a bit
skeptical that it’s much of an issue in humans if consumed at a fairly
reasonable level, but don’t have any specific information on that point
for you.
In horses, hypothyroidism
tends to be pretty wildly overdiagnosed and overtreated---I’m not saying
it doesn’t exist, but for most horses, thyroid inhibition just isn’t
a major issue, except in horses that have clearly defined metabolic syndrome issues.
Flax does contain some goitrogenic compounds, as well as cyanogenic glycosides,
much more so in the plant, leaves and immature seeds than in the mature seeds
typically fed. In the amounts typically fed to horses, it’s highly
unlikely goitrogenic compounds would be an issue to even the slightest extent
in ‘normal’ horses. I know of several horses competing at
international levels that go through better than 5 pounds a day, and there ain’t
nuthin wrong with those horses at any level.
As for the cyanogenic
compounds, those are potentially an issue for ruminants that possess the
digestive enzymes that break down the compounds into harmful components. Cows
and sheep have those enzymes in sufficient numbers to potentially cause a
problem if they consumed a pretty vast amount of flax or linseed cake, but
horses don’t. Horses have these enzymes only in very low
concentrations, insufficient to degrade the cyanogenic compounds to any
significant extent, so again, it’s a non-issue, IMO. Aside from all
of that, selective cultivation of flax has reduced the cyanogenic content to
virtually trace amounts, only---as a bit of trivia, raw soy is actually
sky-high in the stuff, but it’s inactivated by cooking or fermentation.
If any of this worries you, though,
you might also consider chia seeds as a source of omega-3s. I haven’t
finished up my reading into it (a very accomplished endurance rider friend just
sent me something not too long ago), but it seems to be very promising as an
equine supplement and has been happily fed to humans for a long time.
>Also, are there any
suggestions to diet modification if any for a horse that may be
"pre-cushings?"
Pre-cushings in what
way? Laminitis, cresty neck, that sort of thing?
