I'm slowly but surely working my way through all the nutrients you guys have been asking
about in this series on nutrients of concern, I've had a few requests for iodine and vitamin
D and the likes - don't worry, those videos are on the way as well, so stay tuned!
If there are any other nutrients you'd like to see covered, let me know in the comments
section below.
Today we're going to be looking at zinc.
Despite zinc deficiency being the most common micronutrient deficiency...in PLANTS, partly
due to our depleted soils, there is a large range of healthy whole plant foods that provide
this mineral and it is relatively straightforward to hit the RDA number with a sensible plant-based
diet.
However, the matter is not quite as simple as that.
These plant sources of zinc tend to also be good sources of phytate.
Phytate provides numerous health benefits and is good for us overall, but of relevance
to our current discussion, phytate binds certain minerals in the alimentary canal making them
unavailable for absorption.
This is of comparitively little concern when it comes to minerals found more abundantly
in whole plant foods like calcium and iron, since we don't mind taking a bit of a hit
on our absorption of those for all the benefits we get, but zinc intake is potentially already
borderline to start with even in well-planned plant-based diets, and phytate has a higher
affinity for this element.
This is why some nutrition authorities recommend vegans take in more zinc than the usual RDA
- vegan diets tend to be higher in phytate.
These recommendations range from no extra requirement at all since the body appears
to be able to adapt to this lower intake by increasing absorption and reducing losses,
right up to recommendations for a whopping 50% extra!
But we must remember that it is the phytate that is driving this requirement up - not
a vegan diet per se.
You could eat an omnivorous diet with lots of unprocessed plant foods and have a higher
zinc requirement than someone eating a junk food vegan diet.
Indeed, more recent zinc dietary reference intake literature reflects this, favouring
tailoring zinc intake to phytate intake, rather than a vegan vs. omnivore dichotomy.
In an unusual reversal of fortune, in the case of zinc the more whole unprocessed plant
foods you eat and hence the healthier your diet is, the worse the situation becomes!
So more importantly, how are the levels of those eating plant-based affected?
Serum levels do indeed seem to be marginally lower in vegans, although this is of questionable
relevance given that several factors affect serum zinc concentration outside of overall
status, and hence it is not a good marker.
Indeed, this is a research priority in the study of zinc - the identification of a better
biomarker and something we can actually assess status with more reliably.
So what to we do until then?
We have no way of knowing whether the slightly lower serum level observed in vegans is enough
to be concerned about or cause health issues, so until we do I propose a few strategies
to help optimise zinc status in those eating a healthy whole foods, plant-based diet with
their concurrent high phytate intake.
First of all, obviously it's important to eat zinc-containing foods!
Legumes, whole grains, nuts and seeds all tend to provide zinc, some of the best of
which I find are pumpkin seeds, hemp seeds, chia seeds and oats.
Nutritional yeast is another good source, with the added bonus as it pertains to zinc
of being phytate-free.
Unfortunately, zinc deficiency is the most common micronutrient deficiency in plants
themselves and I think this is part of the reason why we are seeing lower levels in those
people that centre their diet on plants, as well as lower total zinc intake.
In addition to including the best plant sources of zinc, there are a number of strategies
we can employ in how we prepare them to boost the bioavailability of the mineral.
Both sprouting and soaking grains, legumes and seeds reduce phytate content.
Leavening of foods, as is done with most breads, enhances zinc absorption, as does fermentation
such as with tempeh.
Co-consumption with protein, onions, garlic, vitamin C and other organic acids such as
those found in cruciferous vegetables will all aid absorption, as well.
I recommend tracking your intake from your usual diet with Cronometer for a few days,
too.
If you're consistently not getting at least the RDA in despite focusing on higher-zinc
whole plant foods, or perhaps if you're new to a plant-based diet and all of this seems
like a lot of work, or maybe you simply want some peace of mind and take this element of
worry and planning out of your diet, I recommend supplementing - but again this isn't as simple
as picking up the first zinc supplement you see and taking it whenever.
For the purposes of preventing zinc insufficiency, we want a supplement that provides no more
than around 100% of the RDA - there is no need to go any higher and run into potential
problems.
We also want a zinc chelate rather than an inorganic form since they appear to be more
easily absorbed.
If you can find it, zinc gluconate is probably the best since it has been shown to have the
lowest levels of cadmium contamination.
Next, when taking your zinc supplement there are a few things to bear in mind.
We want to avoid taking it around the same time as calcium-containing foods and supplements,
and also tea and coffee, which can all interfere with the absorption of zinc.
In fact, probabaly the best time to take zinc is on an empty stomach, unlike most other
supplements.
I take it last thing at night as I find it helps with sleep.
No discussion on zinc is complete without mentioning it's ratio to copper so I'll finish
up with a quick word on that.
I mentioned not supplementing any more than 100% of the RDA of zinc, and one of the reasons
for this is that high doses that would never be found in nature interfere with copper absorption.
This may actually render zinc supplementation on a whole foods, plant-based diet safer,
since this diet tends to be higher in copper making it less likely for one to run into
insufficient copper intake.
Also please note that serum copper to zinc ratio is a completely different topic to dietary
ratio, and is beyond the scope of this video.
Before we finish, I want to acknowledge that this topic is pretty complicated and you might
be getting the impression from this video that zinc is impossible to get on a plant-based
diet.
But overall, in well-balanced diets the inhibitory effect of phytic acid is low and there is
little evidence from nutritional surveys that in a well-nourished population, dietary phytate
may have a negative effect on the absorption of minerals.
Quite reassuring!
In summary, zinc is one of those nutrients that's a little trickier to hit the RDA of
on a plant-based diet.
Also, the healthier your diet is, the more zinc you may need.
Zinc-containing whole plant foods are all foods you should be including in your diet
anyway for lots of other reasons.
It is prudent to track your usual diet to assess your zinc intake, and supplement if
neccesary or simply for convenience.
I hope this video was useful and gave you a better understanding of dietary zinc!
If there was something that wasn't clear from the video or you have any questions or comments
feel free to leave them in the comments section below and I'll get back to you.
Be sure to share this video with anyone you know who may be concerned about zinc and hit
that like button if you found this overview informative.
That's it for now though guys, talk to ye soon.
Sláinte!