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Hey everyone, it's Mikki here. You're listening to Mini Mikkipedia on a Monday and I want to chat about zinc today and whether or not it's a supplement that can aid in sleep in a way that might be over and above just to correct a deficiency. And I went to the literature to have a look at what research exists, particularly for midlife women or endurance athletes. And I want to share with you what I've found.

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So firstly, let's have a chat about the mechanisms about how zinc can affect sleep. So through GABA-A receptor modulation. So zinc acts as an allosteric modulator of GABA-A receptors. These are your main inhibitory neurotransmitter receptors in the brain. Think of GABA as your brain's brake pedal. When GABA binds to these receptors, it calms neural activity down.

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Zinc enhances this effect and interestingly it binds to a similar site as benzodiazepines like Valium but without the dependency risk or morning grogginess and probably way less effective if I'm honest. To be really clear at very high pharmacological doses so we're talking 100 milligrams plus or acutely toxic levels zinc can directly bind to these

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benzodiazepine receptor sites on GABA-A receptors, producing direct sedative effects similar to how that valium might work. But at physiological supplementation doses, you're nowhere near these receptor binding thresholds. I'm talking 15, 30 milligrams. Instead, zinc is working through other roles at helping with that GABA function, such as the neuromodulation of excitatory pathways and supporting normal HPA access function.

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The key distinction here is that a high dose might directly bind to those receptors, but low doses is much more supportive and much more sort of physiological. And speaking of neurotransmitter balance or cofactors, the zinc is a cofactor for enzymes involved in neurotransmitter metabolism, particularly glutamate and GABA. Studies show that zinc deficiency can throw off the balance between these excitatory and inhibitory signal.

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Glutamate is an excitatory signal and gabot is that inhibitory or that break. And the deficiency can disrupt sleep and contribute to insomnia. Now that is different from being a sleep supplement because you were correcting a deficiency rather than putting zinc into an already zinc replete environment. The zinc is also involved in the enzymatic pathways for melatonin production.

02:42
Clinical trials show that zinc deficiency disrupts melatonin synthesis in the pineal gland. There's actually a complex bi-directional relationship between GABA and melatonin in the retina and pineal gland, and zinc sits right in the middle of this. However, these studies haven't been replicated in human trials at this point, and they are just animal studies. Zinc also influences circadian clock gene expression and helps regulate the sleep-wake cycle.

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Studies in healthy populations show that people who sleep a normal seven to nine hours per night have the highest serum-zinc concentrations compared to those people who are short sleepers under seven hours and long sleepers over nine hours. So mechanistically, through receptor modulation of the GABA-A receptor, through neurotransmitter balance, through melatonin synthesis,

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and circadian rhythm regulation, there are legitimate pathways with which how zinc can affect sleep status. The question though is that does supplementation actually work in humans? So there was a systematic review published in October 24, which analyzed eight randomized controlled trials on zinc and sleep. The interventions range from four to 48 weeks, quite a wide length of time with doses between 10 and 73 milligrams per day.

04:06
The majority of studies actually showed improvements in sleep quality, but here's the critical detail. Almost all positive results were in populations likely to be deficient in zinc. So let's have a look at the breakdown. Studies that showed benefit were in older adults with 30 milligrams of zinc daily for 10 weeks, significantly improving sleep quality. In ICU nurses, so 220 milligrams of zinc sulfate every three days, about 73 milligrams a day,

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for one month improved subjective sleep quality, reduced sleep latency and improved overall sleep quality scores. In hemodialysis patients, 30 milligrams of zinc gluconate for 12 weeks improves sleep quality. And infants in developing countries, zinc supplemented infants, set an extra 1.7 hours per day. So that sounds pretty promising. What studies were there no benefits? There were no benefits in young women with PMS.

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30 milligrams of zinc for 12 weeks showed only marginal improvement. In chronic fatigue patients, a combination of zinc and melatonin showed no significant improvement. In well-nourished athletes during sleep restriction, multiple studies of ZMA, which is Zinc Magnesium B6, in healthy athletes with adequate nutritional status showed zero benefit for sleep. So you can see that pattern that I've just described.

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Benefits for sleep shows up when you're correcting a deficiency, not when you're loading up on top of adequate status. So this is fundamentally different from how you see particularly ZMA, which is zinc, magnesium and B6 marketed as a universal sleep aid. Even it suggests it's more accurately as correcting zinc deficiency can improve sleep quality. So this doesn't mean that you throw it off the table because this may matter for you. What are...

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The risk factors for being deficient in zinc. So firstly, for athletes, there are a higher risk of zinc deficiency because of sweat losses. So zinc is most is lost in significant amounts through sweat, especially during long training sessions. Higher metabolic demands, more zinc is required for tissue repair and enzyme function. Dietary restriction, many athletes restrict calories or certain food groups for weight management. And plant-based diets, vegetarian and vegan athletes are

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greater risk since zinc is primarily in animal sources in a bioavailable form. So the recommended dietary intake for zinc is 9.5 milligrams for men and 7 milligrams for women, but athletes actually may need more. We know that in well nourished athletes with adequate zinc status, supplementation doesn't improve sleep, even during periods of sleep restriction. But there are observational trials in elite female athletes and one in particular Australian footballers found that higher zinc

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intake was associated with better sleep efficiency. So it does suggest that maintaining adequate zinc status matters. And you can get zinc from red meat, especially grass-fed beef and lamb, shellfish, oysters are certainly the champion there, turkey and fish. And if you are vegetarian, you can get it from pumpkin seeds, cashews, hemp seeds, lentils and chickpeas.

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and some dark chocolate, albeit not in as bioavailable forms. But if you are an athlete who sweats a lot, trains hard, and might not eat much red meat or shellfish, you might actually be one of these people who would benefit from zinc for sleep. And what about in midlife women who struggle with sleep? I will say that this is where there is just not a lot of good data in here. We know from a Spanish study of postmenopausal women

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that 58.3 % are deficient in plasma zinc levels, particularly due to hormone changes, such as declining estrogen, which increases the risk of zinc deficiency. In perimenopause, you need zinc for FSH and LH production, which are the hormones that regulate your cycles. And in postmenopause, zinc is essential for aromatase activity, the enzyme that converts androgens, such as testosterone, into estrogens, which becomes your primary estrogen source.

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And there are also structural changes as well. Most zinc in the body is stored in muscle and bone, both of which are changing during menopause. And if you're not actively working at protecting your muscle and your bone, you may be losing it. Risk of sarcopenia and osteoporosis are both linked to zinc deficiency. And if you are doing intense exercising, but not replacing zinc and looking after yourself nutritionally, you may be depleting zinc even faster. And let's consider,

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In addition to the deficiency data, why you might benefit from zinc anyway. Beyond sleep, zinc helps with mood regulation. It can help improve depressive symptoms in premenopausal women, cognitive function, maintaining memory and concentration, bone density, essential for bone health. With vaginal dryness, it's important for the mucos membrane health and self lubrication and vitamin D status.

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Zinc supplementation can improve vitamin D levels in postmenopausal women as well. So while we have strong evidence that zinc deficiency is maybe an issue in postmenopausal women, in over half postmenopausal women, sleep disruption is a hallmark symptom of perimenopause. And while zinc improves sleep in other populations when deficient, there aren't any specific randomized clinical trials testing zinc supplementation in perimenopause or menopausal women.

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So I mentioned earlier, there was one study in young women with PMS, which showed only marginal improvement wasn't statistically significant, suggesting that hormone fluctuations may complicate the picture. But for the demographic most likely to be deficient and most likely to have sleep issues, the research doesn't exist. And that is definitely a significant research gap that could be addressed. So what are some key practical takeaways if you're struggling with sleep and

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You may not eat a lot of red meat or oysters, for example. Should you consider zinc? Well, it isn't a foundation sleep supplement, really. But correcting a zinc deficiency may help improve your sleep. The question is really, are you deficient? Are you at risk of deficiency? Are you an endurance athlete with significant sweat losses?

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Are you a perimenopausal or post-menopausal woman with a high deficiency risk? Do you follow a vegetarian or vegan diet? Do you have a restricted calorie intake which reduces your likelihood that you're getting enough zinc because it's hard to get all your nutrients when you're in a calorie deficit? Or do you experience other signs of zinc deficiency like poor wound healing, thinning hair, white spots on nails, frequent infections, reduced sense of taste or smell?

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So these are all signs that you may benefit from supplementation. But ideally you would get tested and you would test zinc and copper ratio rather than just zinc alone. I'll talk about this in a minute. Understand that serum zinc isn't always reliable, but red blood cell zinc or functional tests may be a better indicator. And these are tests that you may need to request specifically. And when you do get these tested, you ideally would have your zinc at around 15.

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Let's very quickly talk about the copper to zinc ratio. Zinc and copper use the same absorption pathways in the gut. High dose zinc, over 40 to 50 milligrams daily, can block that copper absorption and create a deficiency. This is why you can't supplement zinc in isolation. You just need to know where both minerals stand. You can have normal copper and normal zinc. If the ratio is off, then you've got a problem. The ratio is a better mark of inflammation and oxidative stress than either mineral alone.

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There was a study in around 500 elderly Italians showing that those with the highest copper to zinc ratio, 1.78 for men and 2.06 for women, had increased inflammatory markers and higher mortality rates. What causes high copper to low zinc? Most commonly, it's copper pipes or cookware, it's hormonal birth control or a predominance of estrogen to podestrone because estrogen can drive copper levels up.

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high copper levels can cause higher estrogen and so forth. can be a bit of a vicious cycle. And also, of course, a zinc-poor diet. The effects of this are inflammation and oxidative stress, anxiety, depression, mood disorders, poor sleep because of zinc's role in that melatonin pathway, and weakened immunity. And low zinc to high copper, which is less common, often comes from oversupplementing zinc without monitoring.

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And the effects of this can be low white blood cells, anemia, may get nerve damage, bone weakness even, and poor wound healing. So how to know? You want to order serum copper and zinc on the same blood draw, calculate the ratio, optimal is roughly 0.7 to 1. And if you can get it, a seroplasmin shows if the copper is properly bound. So.

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Ideally, you would never supplement either mineral without knowing where both of them stand. And if you do supplement zinc, you want to dose 15 to 30 milligrams per day. This is the dose that is used in most studies that showed a benefit and do not exceed 40 milligrams a day long term to avoid that copper depletion. Ideally, the form of zinc would be zinc cholinate, zinc citrate or zinc biglycinate. All three of these are well absorbed and

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Taking with food, maybe dinner, take it outside of any iron supplement you'll be taking because the two also bind to the same receptors. So take iron in the morning, zinc at night. Zinc on an empty stomach can cause nausea for many people. And see how you go when you supplement for around eight to 12 weeks and to see what benefit you might get. So don't expect zinc to work like a sedative. So it's not going to knock you out or dramatically change your sleep overnight.

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If you're deficient, the benefits will be gradual. You'll get better sleep quality, easier time falling asleep, less fragmentation throughout the night. And crucially, if you're already getting adequate zinc from your diet and have a good zinc status, supplementing more won't give you super sleep. This isn't a case where more is better. So hopefully that was informative for you. And if you do struggle with sleep, you fall into a category where you might be deficient, get that zinc and copper.

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tested, assess whether or not you need a supplement, then supplement with the guidelines that I suggested and just see whether it makes a difference. If you are deficient in zinc, it is much more than your sleep that will be impacted. Your recovery, your gut health, your mood, your immune system, all of these things may be impacted with lack in zinc. So your sleep might just be a mere sort of uh part of that as well. All right, team, hope you're having a great start to 26.

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Let me know what you think. I'm on Instagram X or threads @mikkiwilliden, Facebook @mikkiwillidennutrition or head to my website, mikkiwilliden.com. Scroll right down to the bottom and pop your name in the little box that gets you on my email list to get more insights like this weekly in your inbox. All right, team, have the best week. See you later.