Nature Made Hair-Skin-Nails Review
Product Focus: Thyroid HealthAlso covers:Hormones
Tier ⓘ
Tier 4 · Rank 7
Tier 4 · Emerging. A promising mechanism or animal data, with thin human evidence so far. Rank 7 within Tier 4 for Thyroid Health; 33 of 59 overall. Tiers run from 1, the strongest evidence, to 5. How we grade →
Evidence ⓘ
15 /100
How strongly the evidence says this product works: human studies count most, then real reviews, then our biohacker panel.
Biohacker Mentions
0 of 10
We don’t sell supplements. We help you make decisions and get the best price.
Lowest prices
We may earn a commission from some store links. How we choose.
Finding the lowest prices at the stores now. This takes a few seconds.
Study, Trial or Testing Result Summary
Members Only57 human studies · 16 improved
2 of these 57 human studies gave the ingredient by drip, not by mouth.
57 human studies16 improved31 no effect606,200 people studied
Zinc is the only ingredient that reaches a studied dose, and only at three servings a day. In people with an underactive thyroid, a pooled analysis of 35 trials found that adding zinc to meds raised active thyroid hormone, though certainty was low. Zinc combined with magnesium and vitamin A raised thyroid hormone with high certainty [1]. A 10 week trial of zinc with magnesium and vitamin A raised thyroid hormone [2]. Other trials found small or no changes [3][4][5], and a review called the evidence inconclusive [6]. Vitamin A here is far below the studied dose. Trials at much higher doses lowered thyroid-stimulating hormone in people low in vitamin A [7][8], while a short trial found no change [9]. Vitamin C is also below the studied dose, and its results are mixed. One larger placebo trial found no difference [10], while small studies found some benefit [11][12]. Copper is below the studied dose and has little support [13][14]. Biotin has no evidence of helping the thyroid. High blood levels of biotin can distort thyroid blood tests, so tell your doctor before testing [15]. Animal and cell studies are never counted.
See all 57 studies →Hide the studies
- A pooled analysis of 114 observational studies found lower zinc in thyroid cancer tissue, but it did not test zinc supplements and is about cancer rather than thyroid health.Serum and tissue zinc in epithelial malignancies: a meta-analysis.
- In a pooled analysis of 35 trials with 3,508 people with underactive thyroid, adding zinc, magnesium and vitamin A to a med raised free thyroxine compared with placebo, though exercise combined with a med did best for thyroid-stimulating hormone and quality of life.Additional treatment strategies for hypothyroidism: a network meta-analysis.
- Across eight studies of 1291 people, those with thyroid cancer had higher blood copper levels than healthy people, but no copper was given, so this shows an association only.The Association Between Serum Levels of Selenium, Copper, and Magnesium with Thyroid Cancer: a Meta-analysis.
- A pooled analysis of 32 observational studies found people with underactive thyroid had lower blood zinc than healthy people, but it did not test zinc supplements.Trace Element Status and Hypothyroidism: A Systematic Review and Meta-analysis.
- A pooled analysis of 10 observational studies found blood zinc was not significantly lower in people with thyroid cancer than in healthy controls.Zinc Status and Occurrence of Thyroid Cancer: Systematic Review and Meta-Analysis.
- A review of 11 studies found conflicting results for vitamin A supplements and thyroid cancer risk, so the evidence was inconclusive.Vitamin and mineral supplements and thyroid cancer: a systematic review.
- A review of 57 studies on micronutrients and thyroid hormones found trials did not confirm links between selenium, zinc and iron and iodine status, and concluded more research is needed; vitamin A was not singled out with a clear result.Micronutrients, iodine status and concentrations of thyroid hormones: a systematic review.
- A review of eight zinc supplementation studies and ten blood zinc studies found the evidence on whether zinc changes thyroid hormone levels inconclusive because results differed and came only from people with illness.Relation Between Zinc and Thyroid Hormones in Humans: a Systematic Review.
- A review of 13 trials in people with overweight or obesity found zinc raised free triiodothyronine, but this rested on one study in people with underactive thyroid and the overall effect on thyroid function could not be determined.The Effects of Zinc and Selenium Supplementation on Body Composition and Thyroid Function in Individuals with Overweight…
- A review of studies on trace elements and thyroid disease found few supplementation trials, but zinc supplementation lowered a marker of oxidative damage (malondialdehyde) in people with underactive thyroid.The Role of Selected Trace Elements in Oxidoreductive Homeostasis in Patients with Thyroid Diseases.
- In severely burned patients, intravenous trace element supplements including up to 4 mg of copper a day for 3 weeks were reported to be safe, improve recovery and normalize thyroid function, but copper was given with selenium and zinc and the abstract gives no patient numbers.Trace element requirements in critically ill burned patients.
- In 404 South African children aged 5 to 14 with low vitamin A and iodine, a 200,000 IU vitamin A dose given at the start and at 3 months over 6 months lowered thyroid-stimulating hormone, thyroglobulin and thyroid size when given without iodine, compared with placebo.Vitamin A supplementation in iodine-deficient African children decreases thyrotropin stimulation of the thyroid and redu…
- In 138 Moroccan children with goiter and low vitamin A using iodized salt, 200,000 IU of vitamin A at start and 5 months over 10 months reduced thyroglobulin, thyroid-stimulating hormone and goiter rate compared with placebo.The effects of vitamin A deficiency and vitamin A supplementation on thyroid function in goitrous children.
- In 102 people with autoimmune thyroiditis, 500 mg of vitamin C daily for 3 months lowered thyroid antibody levels within the group, but there was no significant difference compared with placebo, and thyroid stimulating hormone did not change.Effects of selenium and vitamin C on the serum level of antithyroid peroxidase antibody in patients with autoimmune thyr…
- In 86 adults with underactive thyroid, 25,000 IU vitamin A twice weekly with zinc and magnesium for 10 weeks raised free thyroxine and lowered an inflammation marker compared with placebo, with no change in thyroid-stimulating hormone.Randomized Study of the Effects of Zinc, Vitamin A, and Magnesium Co-supplementation on Thyroid Function, Oxidative Stre…
- In 84 women, 25,000 IU of vitamin A daily for 4 months lowered thyroid-stimulating hormone in both obese and non-obese women and raised T3, while total T4 fell.The effect of vitamin A supplementation on thyroid function in premenopausal women.
- In 80 postmenopausal women with or without type 2 diabetes, 6 weeks of hormone therapy with vitamin C and E did not significantly change free thyroxine or triiodothyronine levels.Effects of hormone replacement therapy with vitamin C and E supplementation on plasma thyroid hormone levels in postmeno…
- In 68 overweight or obese women with underactive thyroid, 12 weeks of zinc alone or with selenium raised some thyroid hormones (free T3, and free T4 with lower TSH when combined with selenium), but there were no significant differences between groups for most measures.Effects of Zinc and Selenium Supplementation on Thyroid Function in Overweight and Obese Hypothyroid Female Patients: A …
- In 62 very low birth weight infants, adding trace elements to fortified human milk raised zinc intake, but zinc deficiency was rare and the abstract reports no thyroid result.Nutrition of very low birth weight infants fed human milk with or without supplemental trace elements: a randomized cont…
- In 57 people with Graves' disease on methimazole, an antioxidant mix with beta-carotene, vitamins C and E and selenium over 60 days helped them reach normal thyroid function faster than the drug alone.Supplementation with antioxidants in the treatment of Graves' disease; the effect on glutathione peroxidase activity and…
- In 55 people with Graves' disease taking methimazole, adding an antioxidant mix (vitamins C and E, beta-carotene and selenium) for 60 days helped them reach normal thyroid function faster than methimazole alone.The effect of antioxidant supplementation on superoxide dismutase activity, Cu and Zn levels, and total antioxidant stat…
- In 40 people, a hydration drink that also contained vitamin C caused no meaningful change in safety or thyroid hormone measures compared with placebo over 4 weeks, though one thyroid hormone showed a statistically significant main effect.Randomized Trial to Assess the Safety and Tolerability of Daily Intake of an Allulose Amino Acid-Based Hydration Beverag…
- In 40 children with autoimmune thyroid disease, 12 weeks of 25 mg daily elemental zinc did not change thyroid antibodies, thyroid tests or oxidative stress, but children given zinc needed no increase in a med dose, while the standard-therapy group did.Effect of daily zinc supplementation for 12 weeks on serum thyroid auto-antibody levels in children and adolescents with…
- In 31 critically ill trauma patients given selenium for 5 days, adding 13 mg zinc (with vitamin E) produced no additional change in thyroid hormones beyond selenium alone.Influence of selenium supplements on the post-traumatic alterations of the thyroid axis: a placebo-controlled trial.
- In 28 overweight or obese adults on a calorie-restricted diet, 8 weeks of 25 mg daily zinc gluconate plus selenium did not change thyroid function compared with placebo.The Effects of Zinc and Selenium Co-Supplementation on Resting Metabolic Rate, Thyroid Function, Physical Fitness, and F…
- In 12 underactive thyroid patients needing high-dose a med, 1 g vitamin C daily for 16 weeks improved symptom scores and lowered thyroid stimulating hormone more than placebo after adjustment, but the very small size and baseline imbalances limit conclusions.Read the study on PubMed (41210509) →
- In a single-dose study of 12 healthy adults, a zinc-bound form of liothyronine (50 mcg) produced a lower but longer-lasting rise in blood T3 than standard liothyronine, with no tested health outcome.Extended Absorption of Liothyronine from Poly-Zinc-Liothyronine: Results from a Phase 1, Double-Blind, Randomized, and C…
- In seven competitive cyclists, 22 mg of zinc daily for 30 days did not change thyroid hormone levels, although insulin rose later on.Plasma zinc, copper, and serum thyroid hormones and insulin levels after zinc supplementation followed by placebo in com…
- In 110 people with Down's syndrome given zinc for about a year, thyroxine was lower and thyroid-stimulating hormone higher than before treatment, so thyroid function did not improve.Thyroid function and plasma immunoglobulins in subjects with Down's syndrome (DS) during ontogenesis and zinc therapy.
- In 53 patients with mild underactive thyroid and 45 healthy people, vitamin C infused into the forearm artery normalized blood vessel dilation in patients but not in healthy people, suggesting oxidative stress from inflammation impairs vessel function; this was a short-term vessel test, not a supplement trial.Low-grade systemic inflammation causes endothelial dysfunction in patients with Hashimoto's thyroiditis.
- In children with Down syndrome, zinc sulfate supplements restored plasma zinc, TSH and reverse T3 levels that had been abnormal, though the study duration was not stated.Modulation of the neuroendocrine system and immune functions by zinc supplementation in children with Down's syndrome.
- In a small study of 11 iron-depleted women, ascorbic acid supplementation had no significant effect on their responses to cold exposure, which included changes in thyroid hormone levels.Thermogenesis and thermoregulatory function of iron-deficient women without anemia.
- In healthy young and elderly people, 10 days of vitamin A (retinol, 50,000 IU a day) did not significantly change thyroid-stimulating hormone levels compared with placebo.Effects of vitamin A administration on serum thyrotropin concentrations in healthy human subjects.
- In Down syndrome children with low blood zinc, zinc sulfate supplementation for 6 months lowered TSH from about 4.0 to 2.6 mIU/mL, bringing it to levels similar to children with normal zinc.Zinc sulfate supplementation improves thyroid function in hypozincemic Down children.
- In 34 older adults over 6 months, a fruit, vegetable and berry powder that raised blood vitamin C was well tolerated and caused no thyroid-related safety problems, though a marker of protein damage fell before adjustment for baseline differences.Effects of a Commercial Fruit, Vegetable and Berry Juice Powder Concentrate on Metabolic Safety and Cardiovascular Healt…
- In 31 patients with underactive thyroid and gastritis, 500 mg vitamin C taken with a med for 2 months lowered thyroid stimulating hormone in all patients, normalized it in 55%, and raised thyroid hormone levels.Read the study on PubMed (24601693) →
- In 10 sedentary young men, 4 weeks of oral zinc sulfate supplements prevented the drop in thyroid hormone levels that followed bicycle exercise, though zinc did not raise thyroid hormones at rest beyond the pre-supplement values.Effect of fatiguing bicycle exercise on thyroid hormone and testosterone levels in sedentary males supplemented with ora…
- In 9 people with an underactive thyroid, about 4 months of thyroxine replacement cleared fats from the blood faster after a meal containing vitamin A and lowered LDL cholesterol, though this study did not test vitamin A as a supplement.Thyroxine replacement therapy enhances clearance of chylomicron remnants in patients with hypothyroidism.
- In a large cohort of over 566,000 adults followed for years, dietary beta-carotene intake was not clearly associated with thyroid cancer risk.The association between selenium and other micronutrients and thyroid cancer incidence in the NIH-AARP Diet and Health S…
- In a survey of 5,878 US adults, higher vitamin C intake was linked to lower total thyroxine levels, with curved patterns for other thyroid hormone measures, so the effect on thyroid function is unclear.Association between vitamin C intake and thyroid function among U.S. adults: a population-based study.
- In a large US national survey of 2,732 adults, dietary vitamin C intake was not significantly associated with risk of Hashimoto's thyroiditis, though higher omega-3 fat intake was linked to lower risk.Investigating the associations between dietary nutrient intake and risk of Hashimoto's thyroiditis: a cross-sectional st…
- In 608 people newly diagnosed with papillary thyroid cancer, urinary zinc levels were not reported as linked to tumor aggressiveness; men had higher zinc than women.Associations between essential microelements exposure and the aggressive clinicopathologic characteristics of papillary …
- In 387 middle-aged and older adults, red blood cell zinc was only weakly and negatively related to total T4 thyroid hormone levels.Basal metabolic rate and thyroid hormones of late-middle-aged and older human subjects: the ZENITH study.
- In a questionnaire survey of 232 Polish people with hypothyroidism, vitamin C was among the supplements commonly taken, but the survey did not measure whether it improved thyroid health.Dietary supplements in hypothyroidism.
- In a retrospective review of 130 people having thyroid surgery, serum zinc levels did not differ significantly between those with papillary thyroid cancer and those with benign disease; copper was higher in the cancer group.Copper as ancillary diagnostic tool in preoperative evaluation of possible papillary thyroid carcinoma in patients with …
- Thyroid tissue from people with nodular goitre contained less copper than tissue from healthy autopsy thyroids.Determination of cadmium, cobalt, copper, iron, manganese, and zinc in thyroid glands of patients with diagnosed nodular…
- A dietary survey of 103 schoolchildren in Adygea found insufficient intake of iodine, zinc, vitamin A and beta-carotene, and the authors concluded that low vitamin A and zinc intake may contribute to iodine deficiency and thyroid problems, but no supplement was tested.[Assessment of the structure and quality of nutrition as a factor that influences thyroid functional activity].
- In a cross-sectional study of 92 women with Hashimoto's thyroiditis, higher dietary vitamin C intake was weakly linked to lower thyroid antibody levels (r = -0.22, p = 0.05), but this was one of several correlations and does not show cause and effect.Parallel investigation of oxidative stress and nutritional profile in women with Hashimoto's thyroiditis.
- Women with newly diagnosed subclinical hypothyroidism had a higher copper to zinc ratio and a higher copper to magnesium ratio than healthy women.Association Between Low Circulating Omentin-1, Vitamin D, Antioxidants, and Trace Elements Imbalances in Women with Subc…
- In 67 adults with an overactive or underactive thyroid, blood zinc levels showed no clear link to thyroid activity.Free amino acids, copper, iron and zinc composition in sera of patients with thyrometabolic diseases.
- In a study of 50 people, serum zinc was lower in thyroid cancer patients than in controls both before and after surgery, while zinc was higher in thyroid tissue; this study did not give zinc and so does not show an effect of zinc on thyroid health.Changes in the Serum Levels of Trace Elements Before and After the Operation in Thyroid Cancer Patients.
- In a retrospective review of 45 Chinese adults admitted with thyrotoxic periodic paralysis, about one quarter had normal red blood cell zinc levels; this was not a zinc supplement study.Thyrotoxic periodic paralysis in a Chinese population.
- In a case series of 22 surgical patients with low vitamin C or thiamin and raised TSH, two patients died from scurvy, and no vitamin C treatment effect on thyroid function was studied.Hypothyroidism Complicated by Vitamin C and Thiamin Deficiency in Surgical Patients.
- This study tested a zinc measurement kit and found red blood cell zinc was lower in Graves' disease than in silent thyroiditis, helping tell the two apart; it did not test any supplement.Measurement of red blood cell zinc concentration with Zn-test kit: discrimination between hyperthyroid Graves' disease a…
- In a 1977 study, people with overactive thyroid excreted more zinc in urine than healthy people, and the extra loss tracked with how severe the thyroid-driven metabolic response was; no supplement was tested.Zinc metabolism and thyroid status.
- In 50 children with biotinidase deficiency taking 5 to 20 mg of biotin daily, high biotin levels distorted thyroid stimulating hormone and other hormone blood tests run on one Roche assay system, so these lab results can mislead diagnosis, while removing the biotin from the sample corrected the error.Serum biotin interference: A troublemaker in hormone immunoassays.
- Five infants aged 8 to 11 months developed yellow skin from eating large amounts of carotene-rich foods, and their thyroid function tests were normal; stopping those foods cleared the yellow color, and the authors described the condition as benign.Benign carotenemia in children.
Review Totals and Summary
Members OnlyWhat buyers say
No written reviews read yet.
Biohacker Summary
Members Only0 of 10 recommend it
0 of 10 biohackers on our panel recommend it
Zinc is the main ingredient here, and all ten panelists spoke about it: four recommend it, five use it, and one warns about dose. Their reasons include immune function, testosterone, wound healing, gut lining, mood, sleep, and having enough zinc before trying longevity strategies. For forms, two of them point to zinc carnosine for gut and stomach problems, and doses mentioned were 15 mg a day for longevity, 30 mg for sperm health before IVF, and a much higher short course around surgery. The one warning is that overshooting zinc can lead to a copper deficiency, and zinc was paired with vitamin C by one panelist and with magnesium by another. Vitamin C, the best known of the smaller ingredients in this product, drew mostly positive comments about collagen and skin, though one panelist stopped using a vitamin C serum because of its smell.
See all 10 biohackers →Hide the biohackers
Dr. Eric Berg · Zinc · recommends
- Recommends ensuring sufficient zinc intake because the prostate needs enough zinc for the conversion from testosterone to DHT to be smooth and optimized.
- Mentions that lemon is loaded with vitamin C, and when combined with coffee, vitamin C significantly increases the bioavailability of antioxidants in the coffee.
- Dr. Berg states that Vitamin C helps fight biofilms and is essential for making collagen in gums, teeth, and capillaries.
- Recommends taking zinc carnosine for an ulcer or some type of gastric problem.
- Recommends Vitamin C as a cofactor, especially for collagen.
- Notes that low vitamin A can lead to dry eyes, dry mouth, and night vision issues.
- Emphasizes the importance of zinc for decreasing viral replication and recommends taking 40 to 60 mg every single day.
- States that high doses of vitamin C, like 2 to 4 grams, can greatly reduce inflammation and support the immune system.
- Notes that birth control pills deplete the body of zinc, which is needed for the brain to make serotonin.
- Added zinc to his creatine product because a deficiency in zinc might make creatine not work as well.
- Mentions that grass-fed liver is loaded with zinc.
- Recommends zinc to enhance testosterone.
- Mentions that grass-fed liver has the active form of vitamin A, called retinol, which is important for eyes, thyroid, immune system, and skin.
- Added copper to his creatine product because a deficiency in copper might make creatine not work as well.
Andrew Huberman · Zinc · uses
- Zinc carnosine to support and improve the lining of your gut.
- Notes that AG1 Pro contains zinc carnosine to support and improve the lining of the gut.
- States that AG1 Pro contains zinc carnosine to support and improve the lining of the gut.
- Uses AG1 Pro, which contains zinc carnosine to support and improve the lining of the gut.
- States that AG1 Pro contains zinc carnosine to support and improve the lining of the gut, and he was already taking some of these ingredients separately.
- States that AG1 Pro includes zinc carnosine, which he was already taking separately, to support and improve the lining of the gut.
- Personally takes zinc carnosine, which is included in AG1 Pro to support and improve the lining of the gut.
- AG1 Pro has zinc carnosine to support and improve the lining of your gut. Some of these ingredients I personally was already taking separate from the AG1 formula.
- States that AG1 Pro contains zinc carnosine to support and improve the lining of your gut.
- Uses AG1 Pro, which contains zinc carnosine to support and improve the lining of the gut.
- Takes a multivitamin every day for longevity.
- Takes a multivitamin every day for longevity.
- Mentions biotin.
- Recommends AG1, a vitamin, mineral, and probiotic drink, and notes that for a limited time, a subscription comes with additional supplements.
Ben Greenfield · Zinc · warns
- Ben Greenfield's formulation includes 30 grams of zinc a day, taken for one week before surgery and two weeks after, as it is an important cofactor for wound healing.
- Mentions that overshooting zinc can lead to a copper deficiency, highlighting the interplay between these elements.
- States that vitamin C is extremely important for collagen turnover and cites orthopedic data showing that 500 mg to 1 g of vitamin C can reduce the rate of complex regional pain in total knee replacements and wrist fractures.
- Notes that Vitamin A is a fat-soluble vitamin that supports healthy skin cell turnover.
- Mentions vitamin C as part of a bare-minimum protocol.
- Emphasizes that zinc sufficiency is crucial for immunity because the thymus-derived peptide thymulin, which trains lymphocytes, requires zinc to be active.
- Notes that while vitamin C has significant value, the optimal dose is a vexed question, and high doses might not always be beneficial, potentially blunting the hormetic effects of exercise.
- Recommends adding zinc into one's stack because it is a co-factor for enzymes involved in testosterone synthesis and sperm maturation, and zinc deficiency is a reproducible cause of low sperm count.
- He mentions zinc as a supplement with real human data behind it for male fertility.
- Zinc may support both testosterone and sperm count.
- Says Formula IQ CopperIQ Serum has stayed in their routine to close out summer strong.
- Notes that IV vitamin C has been used for decades for cancer patients with almost no standardization and that he receives many questions about its effectiveness and combination with chemo.
- Warns that he was taking so much zinc without realizing it because it was in five different things he was taking, and he couldn't pinpoint the problem.
- Recommends supplementing with zinc if deficient, as multiple trials show significant symptom reduction of tinnitus in zinc-deficient individuals.
Thomas DeLauer · Zinc · uses
- Adds zinc to their immunity duo because it helps them absorb vitamin C, considering the two together a fantastic combination for fall and winter.
- Recommends taking vitamin C along with collagen about an hour before a workout for connective tissue benefits.
- Uses vitamin C as part of their immunity duo, stating it is important for boosting the immune system, especially during cold and flu season.
- Recommends zinc, noting it is a cofactor for enzymes that build neurotransmitters, and deficiency can affect mood, happiness, and motivation.
- Recommends consuming vitamin C to aid in NADPH recycling, which is necessary for glutathione to be reused after neutralizing oxidative stress.
- Mentions that more zinc could be beneficial for testosterone, but it's not working on the axis that most people need help with.
- Takes Purity's liquid liposomal vitamin C for immune support and overall wellness, finding it easy to add to water, juice, or take straight up due to its good taste.
- Compares zinc content, noting salmon has under 1mg while oysters have 74mg per 100g, a 70x difference.
- Compares the Vitamin C content of oranges (53mg) to guava (228mg), noting guava has 4x more.
- Recommends keeping zinc levels topped off because it is a critical cofactor for over 300 enzymes and is important for immune cells, testosterone, and wound healing.
- Recommends 15 mg of supplemental zinc if oysters are not realistic, but emphasizes that food source zinc is better as it comes with natural cofactors like copper and selenium.
- States that collagen synthesis is vitamin C dependent, in the context of glowing skin.
- Recommends Vitamin C for sleep, noting that intake in the range of 125 to 200 mg per day is associated with a lower risk of sleep disorders and sleep apnea, with the benefit plateauing beyond this range.
- Recommends consuming a little bit of vitamin C, such as a couple of berries or kiwi, along with flavanol-rich cocoa to help the delicate flavanols hold up and prevent oxidation in the gut.
Dave Asprey · Zinc · uses
- Developed a nonnano zinc sunscreen over five years, stating her skin is probably better now than it's ever been.
- Recommends taking vitamin C for better skin health.
- States that currently, he is only taking vitamin C and vitamin D.
- Emphasizes the importance of having enough zinc before trying advanced longevity strategies like peptides.
- Emphasizes the importance of having enough copper before trying advanced longevity strategies like peptides.
- Recommends real vitamin A for people on the spectrum, noting that many cannot convert plant vitamin A and need the good stuff he includes in his Vitam DAKNE product.
- Suggests that zinc has better safety and protective data than meds for reducing cardio respiratory risk.
- Dave Asprey reflects on how new research clarifies the mechanism behind IV vitamin C's anti-cancer effect, vindicating a decades-old idea that was dismissed for the wrong reasons.
- Takes Vitamin DAKE from Suppgrade Labs because D3, A, K2, and E work together.
- Notes that plain Vitamin C isn't enough and that most people never think to check for a specific ingredient that makes it work.
- Includes vitamin K2 as a critical ingredient in Vitamin DAKE, stating that the body needs the right fat soluble vitamins for thousands of reactions.
- Dave Asprey recommends taking maybe a gram of vitamin C a day in divided doses, noting that plasma levels peak around 250 milligrams twice a day.
- Dave Asprey mentions that he will discuss copper in the episode.
- Recommends Qualia Vitamin C Plus, highlighting its combination of seven forms of vitamin C with 250 mg of citrus bioflavonoids, which helps with absorption and use for building collagen and a strong immune system.
Dr. Mark Hyman · Zinc · uses
- Gave a patient with psoriatic arthritis a little zinc, which contributed to significant improvement in her condition.
- Mentions that vitamin A levels can be looked at to get a deep sense of what's happening with nutrient levels.
- Recommends vitamin C as a basic supplement during detoxification to help with inflammation and detoxification.
- Dr. Hyman mentions vitamin C as an advanced therapy for skin repair.
- Mentions topical vitamin C as an antioxidant that can help skin with aging.
- Mentions that what they do when a cold comes on is not just vitamin C.
- Recommends ensuring adequate zinc intake on a regular basis for immune support, noting some data on zinc lozenges for early cold.
- Recommends taking 50,000 units of vitamin A for three to five days right at the onset of symptoms if one feels they might be getting sick.
- Recommends ensuring adequate vitamin C intake on a regular basis for immune support, stating it's important for healthy immune function despite mixed data on its effectiveness for colds.
- Notes that night blindness is caused by vitamin A deficiency.
- Mentions that vitamin C was the very first vitamin discovered, isolated, and synthesized in 1932, and its deficiency caused scurvy.
- Recommends correcting nutrient deficiencies with zinc.
- Recommends nutrient-dense foods rich in zinc, such as pumpkin seeds and oysters, to reduce inflammation.
- Recommends nutrient-dense foods rich in vitamin C, such as guavas and parsley, to reduce inflammation.
Dr. Rhonda Patrick · Zinc · recommends
- Notes that not getting enough zinc can affect testosterone, as zinc is very important for testosterone synthesis.
- Recommends men take a 30 milligram zinc supplement for sperm health when preparing for IVF.
- Lutein and zeaxanthin can also be obtained from certain multivitamins.
- Lutein and zeaxanthin can also be obtained from certain multivitamins.
- Discusses findings from a meta-analysis on zinc supplementation, noting it improved insulin resistance, inflammation, and oxidative stress in people with diabetes or prediabetes, and explains its biological role in the pancreas.
- Recommends nutrients like zinc for men to prioritize sperm mitochondrial health.
- Recommends nutrients like vitamin C for men to prioritize sperm mitochondrial health.
- Dr. Rhonda Patrick's daughter chugs an Emergency fizzy drink in the morning to ensure she gets some vitamin C and micronutrients before school.
- Choosing a multivitamin that includes lutein and zeaxanthin ensures you get meaningful amounts every day.
- Choosing a multivitamin that includes lutein and zeaxanthin ensures you get meaningful amounts every day.
- Notes that ~35% of Americans are low in vitamin C.
- Recommends increasing vitamin C intake if concerned about skin aging, noting it is an essential cofactor for collagen synthesis.
- Recommends Zinc, stating it is a critical mineral required for testosterone production and that supplementation corrects deficiency-related low testosterone.
- Recommends correcting deficiencies in zinc to directly increase total testosterone by up to 100+ ng/dL.
Siim Land · Zinc · recommends
- States that deficiencies in nutrients such as zinc can impair normal immune regulation.
- Recommends taking vitamin C with collagen to support joint collagen synthesis.
- States that vitamin C is needed for initiating collagen synthesis and that higher vitamin C intake appears to increase vitamin C content in the skin.
- Mentions that copper is a mineral necessary for making collagen.
- Lists sauerkraut and fruit as sources of Vitamin C.
- Lists liver and carrots as sources of Vitamin A.
- Notes that Vitamin C is one of several supplements with human evidence.
- Notes that researchers found vitamin C alleviates ferro-aging, a process of iron overload and lipid peroxidation that drives aging, and that it directly inhibited ACSL4, a protein driving ferro-aging.
- States that Vitamin C has a central role in aging and longevity, and that in monkeys, oral vitamin C slowed ovarian aging during a 3.3-year study.
- States that vitamin C is one of the most important vitamins for staying healthy and aging well, and that intakes of 200 to 400 mg a day from food or supplements largely saturates plasma and neutrophils in most healthy adults. He also recommends spreading out the vitamin C across the day to avoid oversaturation.
- Mentions vitamin C in comparison to topical melatonin for oxidative defense, stating that melatonin would compete but is not as broadly validated clinically.
- Was found to be vitamin C deficient by True Health and Mayo Clinic tests, and now addresses this by eating one extra kiwi fruit daily.
- Explains that zinc raises testosterone only if zinc status or testosterone levels are low, and can reduce the duration and severity of colds and flu, and lower blood sugar and lipids if zinc status is low.
- States that the biggest evidence for multivitamin is that it improves cognition and enhances episodic memory in elderly people, who tend to have worse diets and are more likely to be deficient.
Bryan Johnson · Zinc · uses
- Takes 15 mg of Zinc in the morning for longevity.
- Takes 15 mg of Zinc in the morning.
- Takes 15 mg of Zinc in the morning for longevity.
- Takes 2 mg of Copper in the morning for longevity.
- Uses Vitamin C as an example of how it would be great if people knew that when they took it, it had a measurable amount and wasn't polluted, which is what Brian ensures with his products.
- Applies vitamin C after showering.
- Mentions biotin as an example of an ingredient that AG1 lists with a specific dose, but then contrasts it with other ingredients in proprietary blends where doses are not disclosed.
- Bryan Johnson's baseline measurements showed low zinc, which was easy to fix by adjusting her protocol and supplements.
- Takes 250 milligrams of Vitamin C.
- Recommends adequate Zinc for hair health, noting it is in the Blueprint stack.
- Bryan uses a copper pillowcase as part of his curated sleep environment.
- Recommends Vitamin C for skin health, noting it's good to pair with collagen peptides and is included in the Blueprint stack.
- Bryan Johnson takes Vitamin C daily as part of his Longevity Mix, which is an antioxidant-rich essential vitamin that supports immune function and metabolic energy.
- He uses Vitamin C, typically in a serum, in the morning for skin health.
Peter Attia · Zinc · recommends
- Suggests that zinc and magnesium could potentially help with vasodilation and sleep, particularly for women experiencing severe symptoms in the luteal phase.
- Notes that in mouse studies, there was a combined effect of alpha ketoglutarate with vitamin A for male mice.
- In mouse studies, Peter Attia's team found a combined effect of AKG with Vitamin A for male mice.
- Recommends vitamin C as an important molecule for skin, noting its role as a precursor for collagen synthesis, a powerful antioxidant, and a regulator of complexion for even skin tone.
- Tried a vitamin C serum mixed with ferulic acid but stopped using it because she hated the smell. She notes that topical application of vitamin C far exceeds the levels achievable by ingestion for skin benefits.
- Mentions that a lot of the profound transformation of a cell into a sperm, specifically the making of a tail, is vitamin A driven.
- Warns that biotin, found in many supplements, can completely obscure findings and render a non-LCMS test for estradiol and testosterone irrelevant due to interference with ELISA-based assays.
- Discusses the AREDS formula, which initially included C and beta-carotene with zinc and copper, and later replaced beta-carotene with lutein and zeaxanthin, showing it could delay or reduce the conversion of mild to severe macular degeneration.
- Notes that antioxidants like vitamins A, C, and E have been looked at for cataract formation but have shown no effect.
- States that vitamin C deficiency is associated with an elevated risk of cataract, but supplementation to supranormal levels has not been shown to protect against cataract formation.
- Discusses the AREDS formula, which initially included C and beta-carotene with zinc and copper, and later replaced beta-carotene with lutein and zeaxanthin, showing it could delay or reduce the conversion of mild to severe macular degeneration.
- Mentions the elimination of scurvy through the work of James Lind and the eventual understanding that it was due to vitamin C, initially thought to be just citrus.
- Advises that if taking a biotin supplement, one should discontinue it for at least a few days, if not a week, before a blood test, as it can dramatically skew thyroid values.
- Warns that certain things, like biotin, should not be taken before a blood test because they can mess up readings.
RAL Summary
Members OnlyTier 4 for Thyroid Health
Zinc has some human trial support for thyroid hormone levels at a full dose, but the results are mixed [1][6]. No reviews were counted, so the product cannot rank above emerging.
Take 3 servings a day (3 softgels) to match the dose that worked in the studies.
- Emerging: not enough evidence to rank higher yet.
Where the evidence disagrees: 31 of the 57 human studies found no effect.
More Details
Members OnlyBody systems · Combine with · Possible side effects
Body systems: Endocrine system
Possible side effects: No major side effects reported. Biotin can distort thyroid blood test results.
Supplement Facts
Vitamin A 750 mcg · Vitamin C 100 mg · Biotin 2500 mcg
Supplement Facts
Serving Size 1 Softgel(s)
Servings Per Container 60
Amount Per Serving% Daily Value
| Vitamin A | 750 mcg | |
| Vitamin C | 100 mg | |
| Biotin | 2,500 mcg | |
| Zinc | 11 mg | |
| Copper | 0.9 mg |
Other ingredients: Medium Chain Triglycerides, Gelatin, Glycerin, yellow Beeswax, Water, Rapeseed Lecithin, Soybean Oil, Polysorbate 80.
Directions: Suggested Use: Adults, take 1 softgel daily with water and a meal.
Label source: NIH label database · Report a label change
Show entire label
More thyroid health products
Members OnlyThe highest ranked for the same goal
Read more
Our articles on this subject
- What Supplements and Vitamins Should Not Be Taken TogetherArticle · Sep 7, 2026
- Supplement Redundancy: How to Find the Ingredients You Are Taking Twice, and Why It MattersArticle · Oct 13, 2026
Graded November 6, 2026 by the Reverse Age Lab evidence engine, from human studies, real reviews and our biohacker panel. How we grade. Is this medical advice? No. Rala organizes the published evidence; go over any change with your doctor, especially if you take meds.
Privacy policyConsumer health dataAffiliate disclosureTermsDo Not Sell or Share My Personal InformationCookie settings