Welcome to the second installment of this series on Zinc. In the first blog post, I've talked about the evolutionary history of zinc as well as its downsides.
In this blog post, I'll consider what foods you need to eat to get adequate zinc status, and how to prevent a deficiency from developing. I'll also cover the topic of zinc deficiency and teach you why it's not a side-issue!
But let's first recap the first blog post:
About 2 million years ago your ancestors, which weren't Homo Sapiens yet, started incorporating more animal foods into their diets. Those animal foods, like shellfish and meat, contain higher levels of highly-absorbable zinc.
Plant foods, on the contrary, are almost always more copper heavy compared to zinc, on a proportional basis. Hence, zinc arguably became a much more important mineral driving forward human evolution.
Now, zinc, overall, has tons of different health benefits, such as improving your energy levels, enhancing sleep quality, aiding cognition, making you feel more relaxed, increasing hormonal health, and many other things.
Today, about 2 billion people are zinc deficient. And yes, many of these people can be found in developing nations. Yet, even in developed nations, zinc deficiency or sub-optimal status is quite prevalent.
For that reason, I decided to write out this blog post on the best foods to acquire all your daily zinc needs, and, to consider the reasons you might be deficient.
Zinc Basics (1st Installment Of Series, Click To Read HERE.)
Understanding Zinc Through Understanding Our (Human) Past
Zinc's Overall Health Benefits--And Diseases Affected By Zinc
Section Finishing Thoughts: Many People Misunderstand Zinc's Role Because They Don't Understand Evolution
Optimizing Zinc Intake
Ready? Let's go:
Remember I extensively talked about shellfish in the introduction of this article. I did not mention shellfish without a reason.
Not only are shellfish the food with the highest availability of zinc, the zinc in these foods is also the most absorbable.
The most important factor in consuming zinc is not how much zinc you take in, but how much you're able to effectively utilize.
Absorption is a simple term to describe how much net zinc you're able to utilize when eating a food.
Let me explain with an example:
You can consume lots of zinc through grains, nuts, seeds, legumes, or beans, but that zinc is not used by your body very well if you consume these foods untreated.
With "untreated" I mean that you cannot properly absorb the zinc in these foods without properly preparing them.
Many plant foods contain what are called "anti-nutrients".[15; 16; 17; 18; 19; 20] If you eat such foods they always need to be soaked, cooked, fermented, germinated, or sprouted before you can safely eat them in the first place.
(Don't worry if you don't know what "soaking" or "sprouting" mean. I'll give you a link to a guide on that topic soon.)
Anti-nutrients are substances in plants that are meant to protect the plant from consumption. Properly treating plan food will reduce their anti-nutrient content.
While different types of foods contain different anti-nutrients, the highest levels are found in grains, beans, cacao, nuts, seeds, and legumes.
The hulls of most grains, for example, contain both lots of minerals as well as anti-nutrients. The inner part of the grain can be more easily digested by humans--but is much lower in minerals as well.
If you're eating white bread, therefore, you'll miss out on minerals. Why? By eating white bread you're not consuming the hull of the grain. But if you're eating whole grains instead, you need to properly deal with anti-nutrients instead.
By soaking grains in hot water for 8-24 hours, you'll reduce the anti-nutrient content so that you can fully absorb minerals such as zinc. After soaking, grains need to be cooked. If you skip those processes you'll end up with nutritional deficiencies as so many people on this planet do.
"Phytic acid" is an example of such an anti-nutrient.
Depending on the specific grain, you can fully eliminate phytic acid through that process of soaking and cooking. In other plants, such as nuts, fully removing phytic acid is a lot harder.
(I oversimplify my argument on phytates and anti-nutrients because different types of phytates exist. To be more precise: phytic acid is made up of phosphorus that's not directly bioavailable in humans. The non-phosphorus parts of the phytic acid compound can bind with minerals such as calcium, magnesium, iron, and zinc. Additionally, phytic acid alters gut function unfavorably, further decreasing the net mineral absorption. Besides phytic acid, there are other anti-nutrients such as "lectins", "tanning", and "oxalates".[451; 452; 453] All of these anti-nutrient compounds will lower your net zinc intake if not properly dealt with.)
Of course, small quantities of untreated grains or nuts will not be detrimental to your health--but they won't be optimal either.
Health problems are created when you rely on untreated plant products for longer periods of time.
And that's exactly where most people go wrong:
Even in the developed world many people are relying on plant foods that have not been prepared properly. An improper preparation of plant foods is a recipe for disaster.
You might be thinking: "absolutely all plants?"
Fruits are generally an exception to the preparation process - these foods can thus be consumed raw. How about vegetables? Vegetables often need some cooking time before you can properly digest them.
(I subsume tubers under "vegetables" in that instance.)
In general, I do not support the reliance on grains, legumes, beans, nuts, and lentils as a staple of human nutrition. To me, consuming lots of these foods inadvertently creates mineral deficiencies.
White rice is safe but does not supply you lots of minerals either. Potatoes are also relatively safe. Adding vitamin C to a meal that's rich in anti-nutrients - from vegetables or fruits - also lowers anti-nutrient damage.
Can you survive on these aforementioned foods? Sure. Will your health be optimal when mostly relying on plant foods such as grains, nuts, and beans? No.
The goal of this blog is to move you towards optimal health. Being "average" is (or rather: should be) of no concern to my readers.
Fermenting grains, for example, increases their zinc absorption.[21; 23] Soaking rice and maize also increases their zinc absorption.[22; 24] If you do nothing and eat foods such as nuts untreated, mineral absorption can be lowered over 80%.
Nevertheless, I also know that many readers will keep consuming lots of plants foods anyhow. For that reason, I've decided to include a few steps to properly treat your foods so that they are absorbed well by your body.
Instead of trying to reinvent the wheel, I'd recommend reading this excellent analysis on reducing the phytic acid (and anti-nutrient) content in different types of food.
Click and read that guide.
Are you a visual learner? Watch the following video on properly preparing grains and legumes.
How about combining animal and plant foods though? When you include animal protein with your plant-based meal, mineral absorption levels rise again.
The causal relationship also works the other way around though:
By adding foods that are high in anti-nutrients to animal foods, the mineral absorption from these animal foods is impeded. If you want to optimize your overall mineral status, it's probably best to include an animal-food only meal once in a while.
Phytic acid can help your gut function, may reduce your chances of getting cancers, and stabilize blood glucose. Including plant food with your diet can thus increase your overall health.
In summary, if you're relying mostly on plant foods anyway, what's important is that:
Knowing what I've told you so far, you might be thinking:
"Exactly how much zinc should I get?"
The answer is: it depends...
Let's consider an adult woman:
If you consume lots of food that has very low bioavailable zinc, you need to consume up to 30 milligrams of zinc per day. If you consume foods that have extremely-high bioavailable zinc, you might merely need 5 milligrams per day.
In general, it's recommended that men get 11 milligrams of zinc per day on average, while women should get 8 milligrams per day.
Pregnant women, however, need 11 milligrams, and lactating women 12 milligrams.
Kids? Babies up to 1-year-old need 3 milligrams per day. From age 1, that dosage slowly increases until 12-year-olds are consuming 8 milligrams.
Interestingly enough, the US has lowered their zinc recommendation from 15 milligrams per day to 11 milligrams--even though many people are slightly zinc deficient in the West already.
The be more precise:
In the US, for example, only 42% of elderly people meet their daily zinc intake. Lowering the daily required zinc intake is a quick way to "create much fewer zinc-deficient people". Of course, the solution is only cosmetic, because lowering standards does not solve any underlying problem.
So what's my opinion on zinc dosages?
As often, the answer is "it depends..."
Let's first consider what not to do:
Many studies have been carried out where participants depleted of their zinc levels (consuming less than 5 milligrams a day, with an average of 3 milligrams of zinc per day).[295; 355; 356; 357; 358; 359; 360; 361; 362]
The results zinc-depletion on health are disastrous.
Eating 10 - 30 milligrams of zinc per day will get most people's zinc levels back up (assuming animal food consumption). Zinc levels can get fully restored within 1-3 weeks. From many different studies we thus grossly know how much zinc you should be getting.
(As a side note, these zinc depletion studies are totally interesting from an ethical point of view. Nowadays you would never pass a 0,5-milligram daily-dosed zinc depletion study with a medical ethics board).
Of course, no zinc dosage recommendations is set in stone.
If you're eating lots of foods that are high in anti-nutrients such as phytates, you're going to absorb less zinc from these foods, and need (much) more than 11 milligrams per day as a male.
If you're really active, you probably need more than 11 milligrams of zinc per day as well. If you want optimal health the same is true. Remember that the "recommended daily allowance" is just a statistic under which most people do not become deficient.
An absence of a zinc deficiency does not mean that your zinc levels are optimal...
If you're exclusively eating plant foods, you might need as much as 30 milligrams of these foods to avoid a zinc deficiency. If you're including animal foods, one meal of a few oysters will already supply you with more than your daily need.
To make things simpler for you, let's get calculation somewhat out of the way...
Let's look at the 25 best zinc foods, weighted per 100g (3.3 ounces) while assuming an 11 milligrams per day zinc (absolute minimum) need.
(The percentage of the daily recommended allowance is listed behind the food type. Animal foods are listed in bold. I've included the highest listed variant of the product (i.e., out of 12 oysters I've included the oyster highest in zinc. Duplicates have been removed from the list. Foods have been sourced from nutritiondata.org. Numbers are calculated by me.)
Please keep in mind that because I've chosen to include the highest-scoring zinc value of each food type, instead of the average of many instances of that food type. To get to an average zinc value you might need to subtract 30%-40% of the zinc in these foods.
The average oyster, in reality, thus has closer to 60 milligrams of zinc in it.
(The reason I chose this method is because averaging the zinc intake over hundreds of beef product is un-doable. While the method I describe above is imperfect, at least it's replicable.)
Spices have also been removed from the list because I don't assume anyone eats 100 grams (3.3 ounces) of spices per day.
The best zinc foods?
Animal proteins - mostly stemming from meats and shellfish - and legumes, seeds, and nuts thus rule the day. Eggs, dairy, whole grains, and beans are great runner-ups that are not listed in the top 25.
"Don't eat us! Those oysters
over there contain more zinc..."
So that's that: you now know about the foods highest in zinc. These high-zinc foods are - not accidentally - also the foods that drove our human predecessors to develop much larger brains than our primate ancestors.
Let's now consider how you can make sure you're getting adequate zinc. I'll tell you everything you need to know about zinc deficiency and how to solve that problem.
(Nerd section: where your oysters are grown does matter. When waters are polluted, arsenic, cadmium, chromium, lead, and mercury levels can become problematic. If your general health is good, heavy metals will not be problematic. With poorer general health, I do recommend taking this variable into account.
Want a simple infographic that describes the 10 most important lessons I got from reading hundreds of studies on zinc? Subscribe below:
About 17% of the world's population is currently at risk of an inadequate zinc intake. Other statistics maintain that about 2 billion people - which is more than 25% of the Wold's population.
While developed countries do better than poor countries, zinc problems are not absent from the developed world. 10% of the US population consumes less than half of the daily recommended allowance of zinc for instance.
That number is obscene...
One main reason many people end up with a zinc deficiency is that they're relying too much on plant foods:
Unrefined cereals, which are consumed en masse in many countries, combined with an absence of beef (liver), lamb, shellfish, eggs, and milk, almost certainly cause zinc deficiencies over time.[364; 365]
So, what if you've concluded that you may be zinc deficient? In that case, you've hopefully read the list of foods that are high in zinc.
You thus know what to eat...
Devise a plan.
In the next part of this blog post, I'm giving you several methods to increase the zinc absorption.
What can you learn from the zinc-increasing factors described above?
Animal protein contains many of the co-factors that increase zinc absorption that I've just described: vitamin A and D, selenium, B-vitamins, and lots of milligrams of zinc. If you're zinc deficient, it might be best to avoid combining these animal foods with plant foods during that specific meal.
Again: the best way to make sure you're getting enough zinc is to include one meal per day that's high in animal protein - while not including any plant food in that meal.
Of course, you can consume many plant foods during the other meals you're ingesting during the day.
I think it's paramount to strike the right balance.
I think the maximal absorption of minerals is one of the reasons so many people are turning towards a carnivore diet right now. Mineral deficiencies are extremely widespread - even in the developed world - and more easily cured with a diet that exclusively prescribes animal foods.
While I'm not suggesting a diet that exclusively includes animal foods, there's merit to that strategy.
Returning home with meat:
celebrated for millions of years
with good reason.
I'm not done yet though.
There's more one important step in my argument: looking at the variables that make you more susceptible to creating a zinc-deficiency.
There are several reasons that make you more likely to be zinc deficient:
A full list of all reasons why you might be more prone to be zinc-deficient. It's not just getting enough zinc that's the issue though:
Some people will supplement with crazy amounts of zinc, thinking that more is better. You can easily go overboard though with 50-milligram zinc supplements that are commonly sold.
50 milligrams of zinc equals almost 500% of the daily recommended allowance. If you solely take in zinc as a supplement, without iron or copper, the latter two minerals will get depleted over time.
There's another side of the equation though - the opposite of a deficiency:
You can get:
It's important to understand that you will not just end up with a zinc toxicity by using extreme doses of zinc foods and supplements. On the contrary, it's also possible to be exposed to toxic zinc levels through industrial settings.
Overall, the most important message of this section is that both an excess and deficiency of zinc are bad.
In the next installment of this series, I'll tell you all you need to know about how and when to supplement.
Want a simple infographic that describes the 10 most important lessons I got from reading hundreds of studies on zinc? Subscribe below:
The message is the same as always: rely on healthy food whenever you can!
Hopefully, this blog post has convinced you to include some oysters into your diet once in a while, and some red meat, and some (calf) liver.
These foods are especially helpful because they contain more fat-soluble vitamins and B-vitamins, which further increase absorption.
Because if you don't consume sufficient levels, you'll become deficient in zinc.
Skin problems, a poorly functioning thyroid, being sick very frequently, depression, and altered sensations are signs of zinc deficiency. Excess of zinc, which generally only occurs if you supplement too much with zinc or over-rely on zinc-rich foods, leads to many symptoms as well.
Read the next installment in this series on lab testing your zinc status and the best supplements if you cannot ingest zinc for one reason or another...
This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS), and is currently a health consultant at Alexfergus.com.
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