Episode 10: Two Billion People Are Zinc Deficient-Make Sure You’re Not One of Them

Episode Highlights

Why Zinc Matters
Discover how this tiny mineral powers hundreds of enzymes and controls key gene switches that keep you healthy
Life-Saving Discoveries
Hear the true stories of zinc reversing stunted growth in Iran and curing a once-fatal genetic disease
Core Body Functions
Learn how zinc supports immunity, wound healing, hormone balance (insulin, thyroid, testosterone, stress) and brain health
Optimal Dosage
Find out why the basic RDA may fall short, what ancestral diets suggest, and why 15-20 mg per day hits the sweet spot
Food and Prep Tips
See which foods pack the most zinc (oysters, meat, legumes), simple soaking or fermenting tricks to boost absorption, and when to supplement
Next Steps
Spot the top signs of deficiency and get practical actions you can take today to make sure you’re not one of the two billion missing out

Show Notes

In this episode, Dr. Ravi Kumar uncovers the hidden global epidemic of zinc deficiency affecting two billion people. You’ll learn:

What zinc is and why it matters—as a trace metal essential for enzyme function, gene expression, and structural stability of proteins
The landmark clinical stories—from a 21-year-old boy rescued by zinc therapy in Iran to infants saved from acrodermatitis enteropathica
Molecular mechanisms—how zinc fingers work, why superoxide dismutase needs zinc, and zinc’s role in tissue repair via collagenase
Hormonal regulation—zinc’s impact on insulin storage, conversion of T4 to T3, testosterone synthesis, and cortisol control
Immune defense—zinc’s role in thymulin activity, natural killer cell function, and evidence for zinc lozenges against colds
Clinical trial data—growth spurts in zinc-deficient children, improved glycemic markers in diabetes, faster wound healing, and better cognition in seniors
Optimal dosing insights—why the RDA may only prevent severe deficiency, how ancestral diets and transporter biology suggest 15–20 mg daily, and absorption caps
Food-first strategies—oysters, red meat, poultry, legumes, eggs, and dairy—and how to use traditional methods to reduce phytates and boost bioavailability
Supplement guidance—why zinc glycinate (bisglycinate) stands out for absorption, suggested dosing for omnivores, vegetarians, and vegans, and safety considerations

By the end of this episode, you’ll know exactly how to assess your zinc intake, identify risk factors for deficiency, and implement food-based or supplemental strategies to optimize this foundational micronutrient.

Transcript

00:00:00.000 –> 00:21.765 On this episode of the doctor Kumar discovery podcast, roughly two billion people around the world are zinc deficient. ^[46] That’s a quarter of the global population. So they dosed this child with zinc, and her symptoms completely reversed. A fatal disease had been cured with a single micronutrient. ^[9] Two oysters can give you anywhere from fifteen to twenty milligrams of zinc.

00:21.765 –> 00:49.275 They’re essentially nature’s perfect food based supplement. My name is doctor Ravi Kumar. I’m a neurosurgeon in search of the causes of human illness and the solutions that help us heal and thrive. I want you to join me on a journey of discovery as I turn over every stone in search of the roots of disease and the mysteries of our resilience. The human body is a mysterious and miraculous machine with an amazing ability to self heal.

00:49.515 –> 01:09.250 Let us question everything and discover our true potentials. Welcome to the Doctor. Kumar discovery. Welcome to the doctor Kumar discovery podcast. I’m doctor Ravi Kumar, a board certified neurosurgeon and assistant professor of neurosurgery at UNC.

01:09.250 –> 01:34.140 Today, we’re diving into a fascinating and often overlooked micronutrient, zinc. Zinc is absolutely essential to human biology. Without it, many of our core systems simply break down. What’s alarming is that billions of people, yes, that’s billions with a b, are living with a zinc deficiency, and they are suffering from poor and deteriorating health without knowing why. This doesn’t have to be you, and that’s what this episode is about.

01:34.140 –> 01:56.430 By the end of this episode, you’ll understand what zinc does in the body, how much you actually need, and how to make sure you’re getting enough to optimize your health. So before we begin, let me give you this quick disclaimer. I’m a medical doctor, but I’m not your doctor. This podcast is for informational purposes only. My goal is to help you think clearly about your health so you can make informed choices in partnership with your health care provider.

01:56.430 –> 02:08.030 Also, this podcast is separate from my role as assistant professor at UNC. So let’s get started with the basics. What is zinc? Well, zinc is a trace metal. On the periodic table, it’s represented as z n.

02:08.345 –> 02:29.000 This little ion is critical. It interacts with hundreds of proteins in the body, helping them fold properly and maintaining their structure. Without zinc, these proteins can’t function. This means enzymes that drive vital chemical reactions in your body begin to fail, so does your health. Zinc powers over 300 enzymes and supports more than a thousand transcription factors.

02:29.000 –> 03:01.170 These are specialized proteins that help turn DNA into RNA, which then guides the production of proteins. That means zinc is involved at the very root of gene expression. But zinc’s role doesn’t stop there. It’s a key player in antioxidant defense, particularly as a cofactor for superoxide dismutase, an enzyme that helps neutralize harmful reactive oxygen species. ^[27] It also stabilizes cell membranes and plays a central role in both innate and adaptive immunity, helping neutrophils, natural killer cells, t cells, and antibody producing b cells do their jobs effectively. ^[3], ^[10], ^[25]

03:01.330 –> 03:18.365 On top of that, zinc is essential for hormone synthesis. It affects cortisol regulation, sex hormone production, growth signaling. The whole hormonal orchestra that keeps us in balance depends on zinc. ^[15], ^[16], ^[17] Now here’s the part that’s deeply concerning. Roughly two billion people around the world are zinc deficient.

03:18.650 –> 04:02.660 That’s a quarter of the global population, which lives with impaired immunity, hormone dysregulation, and suboptimal gene expression, often without even realizing it. ^[46] To really understand how we came to appreciate the importance of zinc, we have to step back in time to the early nineteen sixties. During a grand rounds presentation in Iran, doctor Ananda Prasad, a brilliant physician and researcher, was introduced to a 21 year old man who remarkably appeared no older than a 10 year old boy. ^[1], ^[7] He had severely stunted growth, underdeveloped genitalia, rough skin, hepatosplenomegaly, and the overall appearance of a child. His diet consisted mostly of whole wheat bread, and interestingly, he had an intense craving for clay, eating nearly a pound of it per day.

04:02.955 –> 04:24.860 This unusual behavior is known as geophagia, a type of pica where individuals crave and eat nonfood substances like dirt, ice, or clay. ^[6] It’s often the body’s way of signaling a mineral deficiency. And doctor Prasad recognized the pattern. He suspected zinc deficiency, so he started the young man on zinc supplementation. Within a year, the transformation was remarkable.

04:24.940 –> 04:53.420 The patient grew 15 centimeters and underwent full pubertal development. It was the first major clue that zinc played a critical role in human growth and sexual maturation. Doctor Prasad went on to study malnourished children in Egypt who were similarly growth stunted. When given zinc, they too experienced a dramatic response growing an average of 15 centimeters in just six months and entering puberty after long delays. These findings cemented zinc’s role as an essential nutrient for growth and development.

04:53.420 –> 05:22.080 Around the same time, two other researchers, Barnes and Moynihan, made another breakthrough. They were caring for an infant with a mysterious and fatal condition called acrodermatitis enteropathica, marked by skin ulcerations around the mouth and anus, severe dermatitis, hair loss, and chronic diarrhea. ^[9] Up until that point, the disease was universally fatal, and doctors and parents helplessly watched these babies die miserable deaths. But Barnes and Moynihan had a hunch. What if these babies were zinc deficient?

05:22.160 –> 05:41.065 Maybe they weren’t absorbing it properly. It was known at the time that zinc was helpful in treating diarrhea. And one of the miserable symptoms of Acrodermatitis Enterohepathica was continuous diarrhea. So they dosed this child with zinc and her symptoms completely reversed. A fatal disease had been cured with a single micronutrient.

05:41.330 –> 06:09.475 This one simple intervention went on to save countless lives after their discovery. The root cause was later found to be a genetic mutation in the zip four transporter, the protein responsible for absorbing zinc from the gut into the bloodstream. ^[8] These children weren’t absorbing any zinc, And without supplementation, they were dying. These discoveries shifted zinc from relative obscurity into the spotlight of global health. They helped establish modern RDA guidelines and led to zinc’s inclusion in parenteral nutrition.

06:09.475 –> 06:27.495 That’s intravenous feeding for critically ill or malnourished patients. Today, zinc is even part of the World Health Organization’s recommendations. Children with diarrhea in resource poor settings are routinely given zinc supplements, and it works. The diarrhea improves faster, and the kids recover more quickly. Hey, guys.

06:27.495 –> 06:49.960 I hope you’re enjoying this podcast so far, and I have a small favor to ask you. Please take a moment to rate and review this podcast on whatever platform you’re listening to it on, and share it with someone who might find it helpful. That’s how the show grows, and honestly, it’s the only way it reaches more people who need to hear it. So what exactly does zinc do in the body? Well, starters, zinc acts as a structural support for proteins.

06:49.960 –> 07:29.905 It binds and stabilizes protein loops forming what are called zinc fingers, tiny structural motifs that help proteins, transcription factors, interact with DNA. These zinc fingers slot into the grooves of DNA, enabling the transcription factor to switch genes on or off. To form these fingers, zinc coordinates with two cysteine and two histidine amino acid residues, locking the structure into place in the shape of a finger. Without zinc, the finger collapses, and with them, the activity of hundreds of genes are silenced. In the condition we mentioned earlier, Acrodermatitis anthropathica, a mutation in the ZIP4 transporter prevents zinc from being absorbed in the gut.

07:30.065 –> 07:58.835 Without zinc, the zinc fingers misfold, gene expression fails, and the patient suffers from widespread immunodeficiency, severe dermatitis, and stunted development. It’s a striking example of how central zinc is to cellular function. Zinc also plays a key role in enzymes known as matrix metalloproteinases, which are involved in tissue remodeling. One well known example is collagenase, the enzyme that helps break down and rebuild collagen when tissue is injured. Think of an injury like a burnt house.

07:58.835 –> 08:26.425 When you fix the house, you don’t just hammer new boards onto burnt ones. You have to tear out all the bad material and rebuild from scratch. Collagenase, which depends on zinc, allows your body to do that. Without zinc, collagen turnover stalls and wounds don’t heal properly. In fact, one randomized controlled trial in patients with diabetic foot ulcers showed that supplementing with fifty milligrams of elemental zinc daily for twelve weeks significantly reduced ulcer size. ^[11]

08:26.425 –> 08:58.125 Another critical zinc dependent enzyme is carbonic anhydrase. It catalyzes the conversion of carbon dioxide into bicarbonate which circulates in the blood and helps keep our pH in a very tight range. Bicarbonate acts like a buffer preventing the blood from becoming too acidic or too alkaline. If zinc is low, carbonic anhydrase doesn’t function well and pH regulation falters. This has been linked to issues like osteoporosis, kidney injury and even brain calcification, all from dysfunctional acid base balance in the setting of zinc deficiency.

08:58.205 –> 09:35.505 Zinc is also essential for hormone function as we spoke about earlier. One great example is zinc’s role in insulin production and release. In the pancreas, zinc helps store insulin in its crystalline form which is crucial to its proper secretion. Without zinc, insulin signaling weakens, glucose builds up in the bloodstream and the risk for type two diabetes rises. A 2019 meta analysis of 25 randomized control trials found that zinc supplementation at twenty to fifty milligrams per day lowered fasting blood glucose by thirteen milligrams per deciliter and reduced hemoglobin a one c by 0.35. ^[13]

09:35.810 –> 10:02.615 That’s a significant improvement, especially for people with metabolic syndrome and diabetes. Zinc also plays a major role in thyroid hormone metabolism. Your thyroid gland produces mostly T4, a storage form that isn’t biologically active. When tissues need thyroid hormone, they convert existing t four into t three right on the spot and t three is the active form. That conversion is carried out by an enzyme called deiodinase which requires zinc to function.

10:03.020 –> 10:40.710 Without enough zinc, the conversion stalls and metabolism slows essentially resulting in a kind of functional hypothyroidism. Zinc also supports the transcription of thyroid hormone receptors via zinc finger proteins, meaning it’s involved at multiple steps of the thyroid hormone pathway. One study found that adults with mild zinc deficiency who supplemented with 30 for three months had a 15% increase in total t three levels and an 8% rise in resting metabolic rate. ^[14] Then there’s testosterone. In the testes, Leydig cells convert cholesterol into testosterone through a multi step enzymatic cascade.

10:40.790 –> 11:12.830 The final step, converting androstenedione into testosterone is catalyzed by the enzyme 17 beta hydroxysteroid dehydrogenase, which has a zinc binding site. Zinc locks the enzyme into its active confirmation. Without it, the enzyme misfolds and testosterone production grinds to a halt. ^[15] Zinc also acts upstream in the brain in an organ called the hypothalamus where it binds to a receptor called GPR 39 triggering the release of GnRH. That’s gonadotropin releasing hormone.

11:13.055 –> 11:44.255 GnRH then stimulates the pituitary to release luteinizing hormone, which then stimulates the Leydig cells in the testes to produce testosterone. So zinc supports both central and peripheral control of sex hormone production. Zinc is also vital for growth hormone. As we saw in doctor Prasad’s work, when zinc deficient children receive supplementation, they experience rapid growth. Zinc supports the function of cells in the pituitary gland which release growth hormone and also in the liver which produces insulin like growth factor one in response to growth hormone.

11:44.255 –> 12:18.945 In a triple blind RCT involving healthy eight and nine year olds, just ten milligrams of zinc per day for three months significantly boosted I g f one levels showing that zinc alone could accelerate growth in children. ^[16] Zinc also helps regulate our stress response, particularly the production of cortisol. Zinc interacts with an enzyme called 11 beta hydroxylase, which converts the precursor 11 deoxycortisol into cortisol. Zinc stabilizes this enzyme and helps throttle its activity, preventing it from overproducing. Without enough zinc, cortisol output can become dysregulated.

12:19.430 –> 12:50.630 The enzyme breaks down under oxidative stress from all the work it’s doing, and the body’s ability to manage stress collapses. ^[17] So zinc not only helps produce cortisol, it helps control the whole system preventing it from overshooting and eventually burning out. Zinc is also vital to our neurobiology, especially when it comes to memory, learning, and mental clarity. In the hippocampus, the part of the brain responsible for memory formation, zinc is co released with a neurotransmitter called glutamate. This interaction helps regulate signaling involved in how we form and retain memories.

12:50.630 –> 14:02.610 Zinc also stimulates the production of brain derived neurotrophic factor or BDNF, a key molecule involved in neuroplasticity, learning, and memory. ^[18], ^[19] In a small unblinded study of 10 patients with Alzheimer’s disease, supplementing with thirty milligrams of zinc daily for three months improved cognitive scores in eight of the ten patients. In a larger randomized control trial of three eighty seven adults aged fifty five to eighty seven, participants who took either fifteen mg or thirty mg of zinc per day for three months made fewer errors on a computerized test, showing improvements in executive function. ^[20] And a 2023 review of clinical studies concluded that zinc supplementation consistently supports memory, processing speed, and executive function in older adults. ^[21] All of this highlights zinc’s broad neuroprotective role in offering cognitive resilience across the human lifespan.

14:02.610 –> 14:33.260 Zinc’s role in the immune system is where it often receives most of its attention. Zinc is essential for the production of thiamulin. Thiamulin is a small peptide hormone secreted by the thymus gland, which is an organ located behind the sternum. Thymulin acts like a conductor of the immune orchestra, coordinating the activation, proliferation, and resolution of immune responses. It helps bring immune cells out of dormancy, direct them to recognize pathogens, produce antibodies, and then shut down inflammation once the job is done. ^[22]

14:33.580 –> 15:04.460 Mild zinc deficiency can reduce thiamulin activity by up to 50%. But this is fully reversible with supplementation. Studies show that thirty milligrams of zinc per day for just four weeks can restore normal thiamulin function. And another powerful arm of our immune system is made up of cells called natural killer cells, which specialize in identifying and destroying virus infected and cancerous cells. Zinc enhances natural killer cell function by strengthening their cytotoxic machinery, essentially priming them to act more efficiently and more deadly.

15:04.460 –> 15:45.555 In healthy adults, taking thirty milligrams of zinc daily for one week increased natural killer cell cytotoxicity by 40%, which is a dramatic boost. ^[25] Zinc is especially important in the elderly, where immune function tends to decline. Studies estimate that about thirty five percent of adults aged 55 to 87 are zinc deficient. In one double blind randomized controlled trial, older adults who took forty five milligrams of zinc per day had a sixty six percent lower infection rate compared to those taking a placebo, averaging just zero point two nine infections over a year versus one point four infections over the year for those who weren’t taking zinc. You’ve also probably seen zinc lozenges in the drugstore during cold season.

15:45.555 –> 16:11.535 And there’s real science behind them. When taken at the onset of illness, zinc lozenges can reduce duration of the common cold by over two days. ^[26] The mechanism? Zinc ions coat the mucous membranes of the throat and upper respiratory tract where they block a receptor on your cells called ICAM one, the very receptor that cold viruses use to enter and infect cells. By blocking this entry point, zinc limits viral replication and shortens illness duration.

16:11.535 –> 16:44.295 Zinc is also very important in its role as a master antioxidant. One of the most important antioxidants in the body is superoxide dismutase, specifically the copper zinc form called SOD one. This enzyme helps convert superoxide, a highly reactive byproduct of oxygen metabolism, into hydrogen peroxide, which is less damaging and can then be safely broken down. You might remember from our vitamin c episode that vitamin c plays a similar role in reducing oxidative stress, but it doesn’t act alone. Zinc is essential for proper folding and functioning of s o d one. ^[27]

16:44.350 –> 17:15.240 Without zinc, the enzyme becomes unstable and ineffective, compromising your body’s antioxidant defenses at the cellular level. So that’s a brief rundown of what zinc does in our body, and we barely scratched the surface. But the question remains, how much zinc do we actually need? According to the official guidelines, the recommended dietary allowance or RDA is set at eleven milligrams per day for adult men and eight milligrams per day for adult women. ^[32] Those values are designed to meet the needs of basically about ninety seven to ninety eight percent of the healthy population.

17:15.400 –> 17:43.830 There’s also something called the tolerable upper intake level, and that’s the maximum daily amount considered safe for long term use. For zinc, that number is forty milligrams per day in adults. ^[6] Going beyond that for long periods of time, especially in supplement form, can impair copper status and lead to other imbalances. But it’s important to remember that this applies to supplements, not food. Zinc from whole foods doesn’t carry the same risk because it often comes packaged with other nutrients like copper that help maintain balance.

17:43.990 –> 18:04.515 Plus, your body has a built in check. It will simply absorb what it needs and excrete the rest through your stool. Now here’s the big question. Are those eight to eleven milligram a day doses enough to truly optimize your health, to keep all your systems running at full efficiency, or are they just enough to avoid deficiency? The answer in many cases is probably not.

18:04.515 –> 18:38.810 Like many RDAs, these values are designed to prevent overt clinical deficiency, not necessarily to support peak biological function. When we look more closely at how our bodies absorb zinc, we see that the zip four transporters, the same ones that are defective in children with achodermatitis enteropathica, tend to plateau in absorption somewhere around fifteen to twenty milligrams per one time dose. ^[39] In other words, if you consume more zinc than that in one setting, your body stops absorbing it efficiently. That natural cap tells us something about what may be an optimal daily intake. And we can cross check that with clinical data.

18:38.890 –> 19:10.680 When researchers study the effects of zinc on blood sugar regulation, they often use doses from twenty to fifty milligrams per day. For children’s growth and I g f one production, ten milligrams per day has been effective. For immune outcomes like reduced infections, studies use anywhere from fifteen to twenty five milligrams per day. The World Health Organization recommends twenty milligrams a day for ten to fourteen days in children recovering from diarrhea. And when zinc is used to fight off colds, short term dosing can go as high as eighty to ninety milligrams per day, especially in the form of lozenges, although that’s only for a few days.

19:10.680 –> 19:34.630 So clearly, there’s a wide therapeutic range. But again, absorption maxes out at fifteen to twenty milligrams per dose. That means that there was some evolutionary reason for limiting the one time absorption of zinc to fifteen to twenty milligrams. Meaning if we got that much in a single dose, we’re probably doing good for the day. I think looking at evolutionary design is a great way to try to make sense of how we should behave in modern context.

19:34.790 –> 20:01.570 We can also learn from ancestral diets. One study looked at what paleolithic humans may have consumed by analyzing the zinc content in wild plants and animals. ^[34] Using a model that assumed a diet composed of 65% plant foods and 35% animal foods. Their estimates suggested that prehistoric humans probably consumed over forty milligrams of zinc per day. Traditional Inuit diets based heavily on animal foods provide around thirty six milligrams a day. ^[35]

20:01.570 –> 20:35.800 Meanwhile, in more horticultural societies like the Shimani of Bolivia, average zinc intake is around fifteen milligrams per day. ^[36] Rural communities in Malawi come in just under that at around fourteen milligrams per day. ^[37] So depending on diet and geography, traditional lifestyles seem to fall anywhere between fourteen and forty milligrams per day. When we zoom out and take it all in, from ancestral diets to transporter biology to clinical trial data, the sweet spot for his daily zinc intake seems to land somewhere between fifteen and twenty milligrams per day for most people. So how do we actually get to that dose?

20:35.800 –> 20:58.330 Zinc is one of those nutrients I always encourage people to get from food first. For most people eating a omniferous diet, it’s entirely possible to hit fifteen to twenty milligrams per day through real whole foods. Oysters are the poster child of zinc containing foods. They contain anywhere from eight to twelve milligrams of zinc each. ^[38] That means just two oysters in a day can meet or exceed your zinc needs.

20:58.330 –> 21:20.285 Beef, pork, and lamb offer about one milligram of zinc per ounce. So a six ounce steak gives you around six milligrams. Dark meat chicken, like thighs and drumsticks, provides about two and a half milligrams per three ounce serving. Chicken breasts, on the other hand, give you about one milligram per three ounces. One egg delivers roughly one milligram of zinc, while a cup of milk provides under a milligram.

21:20.590 –> 21:38.565 Yogurt is slightly lower, offering about a half a milligram per cup. Plant foods also contain zinc, though typically in lower amounts. Peanuts and soybeans contain about one milligram per ounce or half cup. Mung beans, lentils, and other legumes have similar levels. When it comes to grains, white rice offers about 0.35 milligrams per cup.

21:38.565 –> 22:07.155 Noodles give you about 0.4 milligrams per cup, and refined wheat flour has about 0.6 milligrams per half cup. These are lower numbers, but plant foods also come with another challenge, and that’s absorption. One of the main reasons zinc deficiency is so widespread in populations that rely heavily on cereal grains is because of a compound called phytate. ^[40] Phytates are found in beans, grains, nuts, seeds. And And while they serve an important function in the plant, they interfere with mineral absorption in humans.

22:07.235 –> 22:39.145 They do this by binding to metal ions like zinc and forming insoluble complexes that the body can’t absorb. This is known as chelation. So if you’re eating a bowl of oats, for example, the zinc and iron in that meal may be present but locked away, bound up by phytates, and ultimately pass through your digestive tract unabsorbed. To give you a sense of the impact of phytates, zinc absorption from something like oysters where there are no phytates is conservatively around 21%. With moderate phytate intake, absorption drops to 11.

22:39.465 –> 23:07.275 And with high phytate intake, like wheat, oats, and rice, it can drop to as low as 4%. ^[39] This is why regions with high cereal grain intake often see widespread zinc deficiency, and it’s what likely contributed to the case we talked about earlier, the young man doctor Prasad encountered in Iran. He was consuming massive amounts of whole wheat flour, which is loaded with phytates, and that likely blocked the ability to absorb the zinc he needed. So does that mean you should stop eating beans and grains? Not at all.

23:07.275 –> 23:41.135 Plants contain phytates, yes, but they also contain fiber, polyphenols, and a wide range of beneficial nutrients. The solution isn’t to eliminate them, it’s to prepare them well. Traditional preparation techniques like soaking, sprouting, fermenting, and roasting can dramatically reduce phytate content. Soaking grains and leggings for eight to twelve hours activates an enzyme called phytase, which breaks down the phytates and allows zinc and iron to become more bioavailable. Sprouting seeds or fermenting flours like in sourdough bread or doce further reduce phytate content and enhance nutrient absorption. ^[40]

23:41.490 –> 24:03.705 Even lightly roasting nuts can help. These are simple practices that people have used for generations, and they can make a huge difference in how much nutrition your body actually absorbs from plant foods. Now let’s talk about zinc supplements. Supplemental zinc is widely available, effective, inexpensive, and generally safe. Having one on hand is a reasonable idea, especially if you’re not confident that your diet provides enough zinc.

24:03.705 –> 24:34.565 There are several types of zinc supplements you can buy over the counter. Zinc glycinate, zinc citrate, zinc gluconate, zinc oxide, zinc sulfate, zinc histidine, and zinc enriched yeast. These forms all provide zinc in slightly different chemical configurations, which affects how well they are absorbed. Of all of them, zinc glycinate stands out as the most effective for absorption. ^[43], ^[47] In a six week randomized controlled trial involving 30 healthy women, participants received sixty milligrams of either zinc glycinate, zinc gluconate, or a placebo.

24:34.565 –> 25:02.035 Only the glycinate group showed a significant rise in plasma zinc by week six, both from baseline and compared to the other forms. Other studies have shown that zinc gluconate outperforms citrate, histidine, enriched yeast, oxide, and sulfate. ^[44], ^[45] So if you’re looking for the most reliable form, zinc glycinate is the winner. There’s also zinc picolinate, which may be fairly bioavailable, but it hasn’t been studied as extensively. Personally, when I choose a zinc supplement, I go with zinc glycinate.

25:02.035 –> 25:26.655 It’s affordable, well tolerated, and effective. So let’s lay out a few practical scenarios based on different eating patterns and how much zinc you’re likely getting from food and whether you might benefit from a supplement. I’ll break it down into three categories, omnivores, vegetarians, and vegans. We’re aiming for fifteen to twenty milligrams of zinc per day for optimal health. If you’re an omnivore, meeting that target with food alone is very reasonable.

25:26.735 –> 25:40.345 Imagine a typical day. For breakfast, you have two eggs. That’s about two milligrams of zinc. Add a slice of whole wheat bread and a cup of yogurt, and you’re up to about three milligrams. At lunch, you have three ounces of beef, giving you another three milligrams and maybe some beans on the side.

25:40.345 –> 26:00.690 Let’s say that adds another five milligrams, though some of it might be lost to phytates depending on how it’s prepared. As a afternoon snack, you eat some peanuts. That’s another one or two milligrams. For dinner, you have some chicken or more beef, maybe some tofu and rice, and you pull in another five to six milligrams. Maybe a glass of milk before bed adds another half milligram.

26:00.690 –> 26:18.425 Altogether, that day adds up to about eighteen milligrams of zinc, and that’s without needing any supplements. You’re right in that Goldilocks zone between fifteen and twenty milligrams. And if you eat like that consistently, you’ll likely stay zinc replete. Now let’s say you’re not sure you’re getting enough. You wanna go for a food based boost.

26:18.505 –> 26:40.650 One of the easiest ways, just eat a couple oysters. Two oysters can give you anywhere from fifteen to twenty milligrams of zinc. They’re essentially nature’s perfect food based supplement. ^[38] Eating oysters fresh is super delicious, and some of my fondest memories are from sitting down in a New Orleans bar with my brother and sucking down raw oysters alongside a cold beer. If you can get them fresh, eat them.

26:40.650 –> 26:52.685 They’re awesome. If fresh oysters are not available, canned oysters will do. But honestly, they’re not great tasting. Now let’s look at the vegetarian diet. Breakfast might be similar, eggs, whole wheat bread, and yogurt.

26:52.765 –> 27:07.530 So you’re essentially starting off like the omnivore. For lunch, you have lentils and tofu, maybe some peanuts for a snack. Then at dinner, you eat black beans, cheese, milk, and some greens. You’re probably hitting around fifteen milligrams of zinc total for the day. But here’s the challenge.

27:07.610 –> 27:30.060 A large portion of your zinc is coming from legumes, which are high in phytates, and that reduces absorption. With that kind of phytate load, your zinc absorption might fall around 10% or more. That means you’re just below the optimal range based on getting fifteen to twenty milligrams with a baseline absorption of 21%. So what can you do? You could increase your intake of eggs and dairy which have no phytates.

27:30.060 –> 27:52.785 Or to keep it simple, just add a small supplement. Even a five milligram zinc glycinate capsule would be enough to get you back into the optimal range. You could also take a fifteen milligram capsule and still stay well below the upper limit. So for vegetarians, a small supplement is often helpful. Even though you might be above the RDA through food, you’re probably not quite at the optimal level unless you’re really optimizing your diet.

27:53.100 –> 28:21.095 Now let’s talk about vegans. I was actually vegan for two years, and while I think it can be a helpful tool in certain situations, it’s worth noting that no traditional culture in the world has ever followed a purely vegan diet. That says something to me. The human body evolved to eat both plant and animal foods, and not one of our ancestors across the world ever thrived in the setting of a plant only diet. In my case, the vegan diet worked for a while, but it ultimately left me vulnerable when other stressors hit.

28:21.260 –> 28:34.860 It eroded my resilience. That’s something I caution people about if they’re following a long term vegan diet. But let’s say you’re vegan and you wanna do it well. For breakfast, you might have whole wheat bread with peanut butter and a tofu scramble. That’s about three milligrams of zinc.

28:35.095 –> 28:57.360 For lunch, maybe mung beans with cooked rice, another seven milligrams of zinc there. Peanuts as a snack, add one or two milligrams. Dinner might include cooked soybeans, which are high in zinc but also high in phytates. By the end of the day, you’re probably consuming around fifteen milligrams of zinc. But because your diet is heavily plant based, your phytate load is high and so is your risk of low absorption.

28:57.520 –> 29:26.880 On a high phytate vegan diet, zinc absorption may drop as low as 4% compared to 21% absorption rate for a phytate free meal. ^[42] So you’re absorbing 17% less. That means even though you’re consuming fifteen milligrams of zinc, you may be absorbing half a milligram to one milligram total. So while you may be getting enough zinc to just barely avoid outright deficiency, you’re skating the edge. And during times of stress, illness, or immune activation, that may not be enough.

29:26.960 –> 29:48.160 You’re right on the line, not deficient, but not fully supported either. This is where a supplement really makes sense. Just like with vegetarians, a five to fifteen milligram capsule of zinc glycinate can bring you back into the optimal range. And because your diet has fewer low phytate zinc sources, the need for a supplement is more consistent. That’s not a knock on veganism.

29:48.160 –> 30:05.755 It’s just a nutritional reality that needs to be acknowledged and planned for. So to wrap up this episode, here’s the big picture. Zinc is a critical micronutrient. It supports immune function, hormone production, growth, cognitive performance, and antioxidant defense. Without it, the body doesn’t run at its best.

30:05.755 –> 30:31.555 And over time, subtle deficiencies can lead to big problems. While the RDA might keep you out of deficiency, the optimal intake for most people is probably closer to fifteen to twenty milligrams per day. If you’re an omnivore, you can often reach that target through food alone. Animal products contain zinc in high amounts and in forms your body readily absorbs. And you can always boost your intake with a supplement or just eat a couple oysters, which is the perfect natural zinc supplement.

30:31.555 –> 30:54.455 If you’re vegetarian or vegan, you’ll likely come in below the optimal range due to lower intake and higher phytate content in your diet. Unless you’re soaking, fermenting, and sprouting your foods regularly, you’re probably not absorbing much of the zinc you eat. In those cases, a zinc supplement makes a lot of sense, especially one that’s well absorbed. I recommend zinc glycinate. It’s also sold as zinc bisglycinate, and they’re essentially the same thing. ^[43]

30:54.455 –> 31:11.370 It’s inexpensive, safe, effective, and supported by clinical data. So I hope this episode has helped you understand just how essential zinc is to human health. It’s not just important. It’s foundational. Without it, our biology starts to break down, sometimes quietly and sometimes dramatically.

31:11.370 –> 31:24.475 So check-in with yourself. Think about what you’re eating, how you’re feeling, and whether your zinc intake is adequate. Because when zinc is missing, nothing in the body works right. But when it’s in place, everything runs at a click. Okay.

31:24.475 –> 31:51.225 For the next episode, we’re gonna do something a little different. We’ve been exploring the world of micronutrients over the past few episodes, but now we’re gonna pivot and dive into a disease process. It’s something you may not have heard of, but there’s a good chance it’s touched your life or the life of someone you know without you even realizing it. The condition is called PANDAS. PANDAS is a disorder where a simple strep infection triggers an autoimmune response that affects the brain.

31:51.225 –> 32:32.090 It often shows up in children as the sudden onset of obsessive compulsive behaviors, tics, anxiety, or even traumatic personality changes. The fact that this condition has gone so under recognized and has likely been happening throughout human history means that there could be thousands, maybe millions or more, children with misdiagnosed psychiatric conditions when the root cause is something that is treatable with a single round of antibiotics. I want to talk about PANDAS because the more people know about it, the more likely it is to be caught early and treated. No child should have to suffer needlessly because no one knew to look. It happened in my family, and it may have happened in yours even if no one gave it a name.

32:32.170 –> 32:59.260 So on the next regular episode, we’ll explore the science, the controversies, and the clinical clues behind this misunderstood and underdiagnosed syndrome. Now before we wrap up, there’s one more thing I wanna share with you. I’ve been releasing these deep dive research episodes every two weeks, and the reason is simple. They take a lot of time. Each one requires a massive amount of research, fact checking, and synthesis to make sure I’m giving you the clearest, most actionable information possible.

32:59.340 –> 33:20.155 I’d love to do them every week, but it’s just not possible. But starting next week, I’ll be adding something new in the off weeks. It’s a new series I’m calling tribulations, and it’ll live within the same podcast feed for now. These episodes will focus on medical stories, many of them historical, some personal, and some that highlight the human side of medicine. Why am I doing this?

33:20.155 –> 33:40.525 First, because storytelling is powerful. It’s fun. It’s compelling, and it connects us in ways that facts alone can’t. But second, and more importantly, we can learn a lot from history, from both the mistakes and the moments of insight. These stories remind us how far we’ve come, how often we’ve gotten things wrong, and how we can do better moving forward.

33:40.525 –> 33:59.470 So stay tuned. Next week, you’ll get the very first tribulations episode. And then the week after that, we’ll be back to our regularly scheduled deep dive where we’ll explore pandas as I mentioned earlier. Thanks again for joining me on the doctor Kumar discovery podcast. If you enjoyed the show, please subscribe, share it with a friend, and leave a review.

33:59.470 –> 34:06.809 It really helps others discover the podcast. And until next time, stay curious, stay critical, and stay healthy. Cheers.