DC Z-Lozenge + Fruit Flavor Review
The product is Z-lozenge+ from Dee Cee Laboratories, a zinc, vitamin C, vitamin D3 and vitamin B-6 lozenge that also includes royal jelly and white willow bark extract in a fruit flavor. The page lists the product under SKU ZL-120-parent and offers it in size options of 120 lozenges and 60 lozenges. The page shows a product image gallery with several views of the ZL-120 bottle and a ZL-60 option. The brand link on the page directs shoppers to the Dee Cee Laboratories brand page. The page indicates that the product currently has no reviews, and it includes a Write a Review link for shoppers who wish to leave feedback. A stock status label and a quantity selector appear on the page, indicating the item can be ordered in the chosen size. A promotional offer states that purchasing six units will ship two additional units free of charge. The scraped text does not include a price figure, an ingredients list, a supplement facts panel, a barcode, or a written description beyond the product title, so those fields cannot be confirmed from this page. Because the page does not show a price or a full product description, buyers should check the live listing for current pricing, serving information, and full label details before purchasing. The lozenge form is inferred from the product name, and the exact count per container is only shown through the size selector options.
Product Focus: Immune HealthAlso covers:Breathing
Tier ⓘ
Tier 4 · Rank 32
Tier 4 · Emerging. A promising mechanism or animal data, with thin human evidence so far. Rank 32 within Tier 4 for Immune Health; 87 of 106 overall. Tiers run from 1, the strongest evidence, to 5. How we grade →
Evidence ⓘ
35 /100
How strongly the evidence says this product works: human studies count most, then real reviews, then our biohacker panel.
Positive Reviews
– no stars shown, 58 reviews
Biohacker Mentions
10 of 10
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Study, Trial or Testing Result Summary
Members Only51 human studies · 17 improved
2 of these 51 human studies gave the ingredient by injection, not by mouth.
51 human studies17 improved18 no effect30,660 people studied
Zinc is the main ingredient here at a full dose. Large reviews found zinc made little or no difference to catching a cold, but taken once a cold started it may shorten colds by about two days, with more mild side effects [1][2]. A review in adults found no drop in respiratory infections but symptoms that lasted about half as long [3]. An older review of zinc lozenges found no clear benefit at seven days [4]. In preschool children, daily zinc cut infection days by a non-significant amount [5]. Vitamin C is below the dose that worked in studies. At 200 mg or more daily, it did not prevent colds in the general public but shortened them slightly [6], and a review of reviews found it does not prevent colds [7]. Vitamin B6 is present, but there is too little direct evidence that it supports immune health on its own [8][9]. Royal jelly, white willow bark and slippery elm are hidden in a small blend with no amounts given and no studies provided here. Animal and cell studies are never counted.
See all 51 studies →Hide the studies
- Across 29 placebo-controlled trials with 11,306 people taking at least 0.2 g of vitamin C daily, colds were not less common in the general public but were about half as common in marathon runners, skiers and soldiers, and colds lasted 8% shorter in adults and 14% shorter in children.Vitamin C for preventing and treating the common cold.
- Across 34 trials with 8526 children and adults, zinc made little or no difference to catching a cold but may have shortened colds by about 2.4 days when used as treatment, with more mild side effects.Zinc for prevention and treatment of the common cold.
- A review of eight systematic reviews covering 31 randomized trials concluded that taking vitamin C does not prevent people from catching a common cold.Does vitamin C prevent the common cold?
- In a pooled analysis of randomized trials in adults, vitamin C slightly lowered the risk of respiratory infections by 4% and shortened symptoms by 9%, with a stronger prevention effect in men and in middle-income countries.Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic revie…
- In 10 placebo-controlled trials of healthy people taking at least 1 g of vitamin C daily, cold severity was 15% lower than with placebo, with a clear benefit on severe symptoms but not on mild ones.Vitamin C reduces the severity of common colds: a meta-analysis.
- A pooled analysis of 28 genetic-based studies found no causal link between blood levels of vitamin D or other micronutrients (including vitamin B6) and COVID-19 outcomes, though a few individual studies reported associations.Micronutrients, Vitamin D, and Inflammatory Biomarkers in COVID-19: A Systematic Review and Meta-analysis of Causal Infe…
- In children with pneumonia, zinc may have slightly shortened hospital stays but did not speed recovery time, and no nutritional supplement could be recommended for routine treatment.A systematic review and meta-analysis on nutritional and dietary interventions for the treatment of acute respiratory in…
- Pooling 6 trials of adults with colds, zinc lozenges did not significantly reduce the chance of having cold symptoms at 7 days.A meta-analysis of zinc salts lozenges and the common cold.
- Five small, low-quality trials with 2,655 children and adults gave vitamin C at 125 mg to 2 g daily, and the evidence was too weak to tell whether it prevents or treats pneumonia.Vitamin C supplementation for prevention and treatment of pneumonia.
- A review of 39 randomized trials of eight supplements, including vitamin C, in healthy people under stress found some signs of benefit but too many gaps to draw firm conclusions about immune protection.Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systemat…
- A review of 13 studies in healthy adults found alternative vitamin C forms often raised white blood cell vitamin C and were better tolerated, with one study showing fewer colds, but more research is needed to confirm immune benefits.Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement …
- This review of common cold treatments covered zinc gel and lozenges among other options, but the abstract gives no results for zinc.Common cold.
- This review of common cold treatments covered zinc gel and lozenges among other options, but the abstract gives no results for zinc.Common cold.
- In healthy adults, zinc did not prevent colds but may have shortened colds by about 2.25 days when given alone.Zinc Supplementation Reduces Common Cold Duration among Healthy Adults: A Systematic Review of Randomized Controlled Tri…
- In 1,444 army recruits taking 6,000 mg of vitamin C daily for 30 days, the risk of getting a common cold was 0.80 times that of those taking placebo.Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised co…
- In 868 Navajo schoolchildren given vitamin C or placebo, there was no difference in how many got ill (133 vs 129), number of illness episodes, or illness length, though blood vitamin C levels were higher.Vitamin C and acute illness in Navajo schoolchildren.
- In 826 Indonesian preschool children given 10 mg zinc daily for 4 months, days with upper respiratory infection fell 12 percent (not significant), and 20 percent after vitamin A was given.Zinc combined with vitamin A reduces upper respiratory tract infection morbidity in a randomised trial in preschool chil…
- In a randomized trial of 688 adult women, 1 gram of vitamin C daily produced a small reduction in chest colds but no effect on simple colds.A randomized controlled trial of vitamin C in the prevention and amelioration of the common cold.
- In 674 marine recruits given 2 grams of vitamin C or placebo daily for eight weeks, colds were no less common or shorter, though the vitamin C group rated their colds as less severe.Vitamin C prophylaxis in marine recruits.
- In 595 critically ill surgical patients, early antioxidant supplementation with vitamin C and vitamin E did not significantly reduce lung complications compared with standard care, but it reduced multiple organ failure and shortened time on the ventilator and in intensive care.Randomized, prospective trial of antioxidant supplementation in critically ill surgical patients.
- In a 5-year double-blind trial of older Japanese adults, 500 mg of vitamin C daily cut the number of people with three or more colds, compared with 50 mg daily, but did not shorten or lessen the colds.Effect of vitamin C on common cold: randomized controlled trial.
- In 275 people with early COVID-19, a 10-day combination therapy including vitamin C was safe and well tolerated, but the study did not test whether it improved immune health.Read the study on PubMed (41693032) →
- In 311 National Institutes of Health employees taking 3 g of ascorbic acid daily for nine months (with extra doses at cold onset), the vitamin had at best a minor effect on the duration and severity of colds, and the results could be explained by a break in blinding.Ascorbic acid for the common cold. A prophylactic and therapeutic trial.
- In a double-blind study of 95 identical twin pairs over 100 days, vitamin C shortened cold episodes by about 19% but had no other significant effect compared with placebo.Vitamin C and the common cold: using identical twins as controls.
- In 120 stroke patients with swallowing difficulty, vitamin C stimulation added to routine swallowing training improved swallowing tests, nutrition markers and antibody levels compared with routine training alone.Effects of vitamin C stimulation on rehabilitation of dysphagia after stroke: a randomized trial.
- In 98 adults with mild to moderate coronavirus illness, 1000 mg of vitamin C daily for 14 days had no effect on symptom progression or quality of life compared with placebo.A Pilot of a Randomized Control Trial of Melatonin and Vitamin C for Mild-to-Moderate COVID-19.
- In 80 healthy adults with a new common cold, zinc gluconate nasal gel used four times daily until symptoms resolved (up to 10 days) shortened cold duration to a median of 4.3 days versus 6 days with placebo.Effect of zincum gluconicum nasal gel on the duration and symptom severity of the common cold in otherwise healthy adult…
- In 60 children prone to recurrent respiratory infections, a daily orange juice providing 70 mg of vitamin C was associated with a drop in infection episodes from about 6.75 to 2.62 per child.Beneficial therapeutic effects of vitamin C on recurrent respiratory tract infections in children: preliminary data.
- In 40 Air Force Academy cadets taking 15 mg of zinc gluconate daily for seven months, self-reported symptom-free episodes were significantly higher than with placebo, but doctor-diagnosed upper respiratory infections did not differ.Use of zinc supplements to reduce upper respiratory infections in United States Air Force Academy cadets.
- In 28 people recovering from COVID-19, a single 1000 mg dose of vitamin C reduced one type of immune-related reactive oxygen species by 45% but did not raise nitric oxide levels.A Plant-Based Dietary Supplement Exhibits Significant Effects on Markers of Oxidative Stress, Inflammation, and Immune R…
- In 24 patients receiving stem cell transplants for myeloma or lymphoma, high-dose vitamin C (20 g daily for 10 days, then 500 mg twice daily until day 100) was linked to rising natural killer and CD3 immune cell counts from day 30 to day 100 and fewer infections, compared with standard care alone.Effect of vitamin C on immune reconstitution after bone marrow transplantation.
- In 20 children having surgery, ascorbate before premedication did not change neutrophil mobility during anaesthesia or surgery, and no infections occurred.Neutrophil mobility during anaesthesia in children. A trial of ascorbate premedication.
- In 12 adults who exercised for about two hours in heat, 1500 mg of vitamin C daily for 12 days lowered the stress hormone cortisol after exercise, but did not change salivary antibody levels or cold-like symptoms compared with placebo.Vitamin C supplementation and salivary immune function following exercise-heat stress.
- In healthy adults aged 55 and older, a 12-week multivitamin and mineral supplement raised blood vitamin C and zinc levels but did not change measured immune function compared with placebo.The Effect of a Multivitamin and Mineral Supplement on Immune Function in Healthy Older Adults: A Double-Blind, Randomiz…
- In older adults, a 30-day course of a multi-ingredient supplement that also contained vitamin C lowered inflammatory blood markers and improved lymphocyte levels, though they did not reach the levels seen in younger people; the vitamin C dose was not stated.Use of Nutraceuticals in Elderly to Fight Inflammation and Immuno-Senescence: A Randomized Case-Control Study.
- In a randomized trial of ultramarathon runners and sedentary controls, taking 600 mg of vitamin C daily was linked to fewer upper airway infection symptoms in the two weeks after a race than placebo, with 33% of supplement takers developing symptoms versus 68% of placebo takers among runners.Vitamin C supplementation reduces the incidence of postrace symptoms of upper-respiratory-tract infection in ultramarath…
- In two trials of 8-9 year old children (172 and 642) given 1000 mg vitamin C daily, cold duration and severity seemed lower but cold incidence stayed the same or rose, and the total sick days were fewer only in the smaller pilot study.Vitamin C as a preventive medicine against common colds in children.
- In about 210 students (three groups of about 70) taking 1 gram daily for 15 weeks, the D-isoascorbic acid group had 34% fewer colds than the other two groups, which included the L-ascorbic acid group, so regular vitamin C showed no clear benefit.L-Ascorbic acid and D-isoascorbic acid in a common cold survey.
- In 60 pregnant women, 30 took magnesium citrate with 40 mg of vitamin B6 daily and were compared with 30 who did not; the treated group had fewer cases of respiratory viral infection symptoms and other complications, but the effect of vitamin B6 alone cannot be separated.EFFECTIVENESS OF THE MAGNESIUM APPLICATION IN OBSTETRICAL PRACTICE.
- In 8 healthy men, a 10-week low-zinc diet (4.6 mg a day) reduced immune cell proliferation, which stayed reduced after 5 weeks of 9.1 mg zinc a day, while immune cell numbers and several other immune measures did not change.Immune functions are maintained in healthy men with low zinc intake.
- In a large double-blind trial, 1 g of vitamin C daily gave a small, non-significant reduction in colds, but more people stayed illness-free and vitamin takers had about 30% fewer days of disability from illness than placebo takers.Vitamin C and the common cold: a double-blind trial.
- In older adults, 500 mg of vitamin C injected daily for one month improved T-lymphocyte response and skin test reaction compared with placebo, but did not change antibody levels.Effect of vitamin C supplements on cell-mediated immunity in old people.
- In a small feasibility study of people with a new common cold, 250 mg of vitamin C daily for 5 days was used only as the comparison arm against a warm humidified air treatment, and the abstract reports no benefit from vitamin C itself.Randomised controlled trial of rhinothermy for treatment of the common cold: a feasibility study.
- In a study of 433 women followed for a year, those with the highest dietary vitamin C intake were less likely to have a persistent human papillomavirus infection than those with the lowest intake.Dietary intake and risk of persistent human papillomavirus (HPV) infection: the Ludwig-McGill HPV Natural History Study.
- In 37 patients with skin infections called phlegmons, those given zinc tablets after low serum zinc was found had no further lesions for more than 10 months, though the study was uncontrolled.Serum zinc levels in patients with phlegmons as a marker of the severity of infection and the potential of zinc suppleme…
- In hospital records of patients with upper respiratory tract infection, adding vitamin C injection to Xiyanping injection did not improve cure rates compared with Xiyanping alone.[Analysis of actual effects of combining xiyanping injection with vitamin C injection in treatment of upper respiratory …
- Young vegetarians and vegans had more zinc deficiency than omnivores, and this deficiency was linked to lower interleukin-2 production and weaker immune function.Reduced interleukin-2 production and increased CREMα protein expression in vegetarians and vegans due to zinc deficiency…
- In 19 hemodialysis patients given influenza vaccine, 4 weeks of zinc acetate (60 mg elemental zinc daily) did not increase antibody responsiveness to the vaccine.Influenza vaccination in chronic hemodialysis patients. The effect of zinc supplementation.
- In 19 healthy older adults, moderate zinc supplementation reduced spontaneous inflammatory cytokine release and improved T cell response to stimulation.Zinc supplementation in the elderly reduces spontaneous inflammatory cytokine release and restores T cell functions.
- In 6 patients with acrodermatitis enteropathica, low zinc levels were linked to weaker T and B cell responses, and these normalized when zinc levels recovered with supplementation.Abnormal immune responses during hypozincaemia in acrodermatitis enteropathica.
- In volunteers with experimentally produced colds, zinc gluconate removed the drop in choice reaction time seen during the cold.Effects of zinc gluconate and nedocromil sodium on performance deficits produced by the common cold.
Review Totals and Summary
Members Only58 reviews
58 reviews · Google 57 · Earthturns 1
Across the stores, the DC Z-Lozenge + Fruit Flavor has 1 rating in total (Earthturns.com), and the themes below come from the written reviews that could be read on that page, which amounted to a single review. Because only one written review was readable, this summary reflects one customer's experience and should not be taken as a broad picture of how buyers feel. The page shows no star rating, no histogram and no percentage breakdown, so satisfaction can only be judged from that one account. What the buyer praises: the review is positive and centers on using the lozenges for prevention rather than treating a cold already underway. The reviewer says it seems to work really well for avoiding colds. How and when it is used: the reviewer takes one or two lozenges in the evening whenever they suspect they are coming down with something, or when someone in the family is sick. They pair the lozenges with half a pink grapefruit. This suggests the product suits people who want a routine they can start at the first hint of illness, or during household exposure, and who are comfortable combining it with a food-based habit. Complaints: none appear on the page. There are no negative comments about taste, size, aftertaste or anything else. That absence reflects only that one review exists, not that buyers have been asked and found nothing to criticize. Taste, form and value: the review does not mention the flavor, including the fruit or strawberry taste, the texture or size of the lozenge, or any side effects. Nothing is said about price or value for money either, so those questions remain unanswered by this page. Caveats: the review is a personal anecdote, not a controlled result. The reviewer's sense that the lozenges help avoid colds cannot be separated from other factors, such as the grapefruit, general health habits or simple chance. It is one experience from one customer. Other product forms: the page was checked for reviews of other forms of the product, such as gummies, capsules or powder, and any such reviews were left out. This summary covers only the lozenge. In short, the only readable feedback is a single favorable account of using the lozenge at the first sign of illness or when a family member is sick, with no stated downsides, but also no information on taste, texture, value or side effects. Anyone considering the product would need to look elsewhere for more detail on those points.
Biohacker Summary
Members Only10 of 10 recommend it
10 of 10 biohackers on our panel recommend it
All ten panelists spoke about zinc, the main ingredient, and every one of them recommends it or uses it, though one of them frames it with a warning. Their reasons vary: four tie it to testosterone, prostate or sperm health, others to immune support, gut lining, wound healing before and after surgery, skin, sleep, and longevity. Doses came up a few times, with one panelist taking 15 mg each morning, one advising men to take 30 mg for sperm health, and another giving a wound healing plan for the weeks around surgery. Forms mentioned include zinc carnosine for the gut and a zinc sunscreen for skin, and one panelist pairs zinc with vitamin C to help absorb it, while another pairs it with magnesium. Vitamin D is a smaller ingredient in this product, and the panel mostly recommends it too, and no one reported stopping zinc.
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.
- Dr. Berg warns that the recommended daily intake for vitamin D is based on a massive error and that the actual necessary amount is closer to 8,895 IU, with millions remaining deficient.
- Recommends getting vitamin D levels tested to ensure they are between 50 and 70, as vitamin D is intimately involved in regulating prostate size.
- Recommends taking at least 10,000 IUs of vitamin D3 every single day in the winter, stating it is the most important vitamin to lower cancer risk.
- Recommends vitamin D to support the immune system, aiming for blood levels between 80 to 100 ng per ml.
- Mentions that lemon is loaded with vitamin C, and when combined with coffee, vitamin C significantly increases the bioavailability of antioxidants in the coffee.
- Recommends taking no less than 10,000 IU's of vitamin D3 for osteoporosis, alongside magnesium and K2.
- Recommends increasing vitamin D to restore balance and support healthy blood pressure.
- 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.
- States that a lack of vitamin D can potentially cause achy bones or crashing mood.
- Recommends Vitamin C as a cofactor, especially for collagen.
- Emphasizes the importance of zinc for decreasing viral replication and recommends taking 40 to 60 mg every single day.
- States that vitamin D is intimately involved in the immune system and recommends taking at least 10,000 IUs each day.
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.
- Notes that most people are probably deficient in vitamin D and benefit from supplementing, but there's no point in doing it unless you're deficient for most things.
- 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 5,000 IU of Vitamin D3 in the morning for longevity.
- Takes 5000 IU of Vitamin D3 in the morning for general health.
- States that Vitamin D is one of the critical nutrients with the best evidence for cognitive function and reducing the risk of dementia.
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.
- 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 D is actually a hormone and recommends patients aim for levels around 40 to 50, or even 60 for fracture healing, for optimal healing, as opposed to just above 20 which is considered normal.
- Mentions vitamin C as part of a bare-minimum protocol.
- Mentions vitamin D as part of a bare-minimum protocol.
- Advises getting vitamin D levels between 60 and 100 nanograms per milliliter as a minimum step for overall health and to slow down heart disease.
- 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.
- 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.
- Has been taking Vitamin D3 K2 for over a decade.
- 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.
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.
- Uses vitamin D3 in the fall and winter months when getting less sun, as it's important to supplement it then.
- Recommends taking a massive amount of vitamin D simultaneously with an early morning massive breakfast to help reset circadian rhythms and address hyperphagia.
- Recommends zinc, noting it is a cofactor for enzymes that build neurotransmitters, and deficiency can affect mood, happiness, and motivation.
- Recommends Vitamin D, stating that it has receptors throughout the brain and deficiency can quickly impact brain and mood.
- Takes supplemental vitamin D because he is skin sensitive and from northern latitudes, limiting his UV exposure.
- Recommends taking vitamin D on non-liver days to ensure both nutrients get proper receptor access.
- 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.
- Takes Purity's liquid vitamin D3 with K2 because she is constantly inside during the day; D3 is for overall wellness and K2 helps the body absorb calcium properly.
- Compares zinc content, noting salmon has under 1mg while oysters have 74mg per 100g, a 70x difference.
Dave Asprey · Zinc · uses
- Developed a nonnano zinc sunscreen over five years, stating her skin is probably better now than it's ever been.
- Takes Vitamin DAKE from Suppgrade Labs.
- Suggests that vitamin D supports brain health, muscle function, and focus.
- Recommends taking vitamin C for better skin health.
- Host Dave Asprey explains why correcting a vitamin D deficiency still makes sense for male fertility, even though supplementation did not improve overall semen parameters in a randomized trial.
- States that currently, he is only taking vitamin C and vitamin D.
- States that currently, he is only taking vitamin C and vitamin D.
- Recommends vitamin D, noting it's actually a hormone and that most people are deficient, even those who take it, because they don't take enough.
- Emphasizes the importance of having enough zinc before trying advanced longevity strategies like peptides.
- States that most people on the spectrum are low in vitamin D and need more of it, mentioning his own product, Vitam DAKNE, which contains real vitamin A.
- Suggests that zinc has better safety and protective data than meds for reducing cardio respiratory risk.
- Dave Asprey recommends Vitamin D3 with K2, explaining D3 is a hormone made from sunlight and K2 directs calcium into bones, not arteries, highlighting its low cost, widespread deficiency, and the ability to test its effectiveness.
- Recommends Vitamin D as one of the most important supplements for overall health.
- 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.
Dr. Mark Hyman · Zinc · uses
- Gave a patient with psoriatic arthritis a little zinc, which contributed to significant improvement in her condition.
- Recommends Vitamin D for health, stating that amazing things happen when patients' vitamin D statuses reach optimal levels.
- Mentions vitamin D as an existing biomarker that plays a role in mental health, which Function Health includes in their measurements.
- Notes that vitamin D plays a role in immune function.
- Recommends vitamin C as a basic supplement during detoxification to help with inflammation and detoxification.
- Recommends checking vitamin D levels and states that if they had to pick one single intervention for immune health, vitamin D would be it.
- Dr. Hyman discusses vitamin D in relation to sun exposure patterns.
- States that vitamin D supplementation can help with oxidative stress.
- 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.
- Mentions vitamin D as a key nutrient for supporting immune function.
- States that vitamin D is probably the single most important intervention for immune health, recommending levels of 45 to 70 and emphasizing testing to determine the right dose.
Dr. Rhonda Patrick · Zinc · recommends
- Notes that not getting enough zinc can affect testosterone, as zinc is very important for testosterone synthesis.
- Vitamin D supplementation was linked to a 40% lower risk of dementia in an observational study of more than 12,000 older adults.
- Mentions that vitamin D also plays a role in maintaining muscle mass.
- Recommends men take a 30 milligram zinc supplement for sperm health when preparing for IVF.
- Recommends ensuring adequate vitamin D intake for men's sperm health.
- Vitamin D and strength training alone did not, but adding them strengthened the effect on one clock, with the full combination slowing that measure by ~3.8 months.
- 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 Vitamin D, noting it regulates over 5% of the genome, including genes involved in immune defense, neurotransmitter synthesis, and longevity, and correcting deficiency may slow epigenetic aging.
- Uses Vitamin D3 as an example of a supplement that an AI model could track to see its impact on other metrics like glucose levels.
- Recommends Vitamin D, explaining that it regulates over 5% of the genome, including genes involved in immune defense, neurotransmitter synthesis, and longevity.
- Combining omega-3s with vitamin D and exercise has an additive effect, translating to ~3 months of slowed biological aging.
- The effect got stronger when omega-3 was combined with vitamin D and resistance training, with the full stack delaying phenotypic aging by about 3.8 months.
Siim Land · Zinc · recommends
- States that deficiencies in nutrients such as zinc can impair normal immune regulation.
- Advises against taking vitamin D in the morning with other supplements because it is fat soluble and requires dietary fat for better absorption.
- Recommends taking Vitamin D with fat for better absorption.
- Recommends taking vitamin C with collagen to support joint collagen synthesis.
- States that Vitamin D connects biology to light and that UVB reaching the skin enables its production.
- 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.
- Lists sauerkraut and fruit as sources of Vitamin C.
- Thinks vitamin D has some of the strongest evidence and is worth considering.
- Notes that Vitamin K2 pairs well with vitamin D by regulating calcium and bone mineralization.
- Notes that Vitamin C is one of several supplements with human evidence.
- Recommends taking vitamin D supplements with some fat to maximize its absorption, suggesting with food or a teaspoon of olive oil.
- Notes that taking vitamin D3 with a fat-containing meal resulted in 32% higher peak blood vitamin D levels.
- Recommends taking Vitamin D in the morning or at lunch with fat.
- Notes that Boron improves vitamin D.
Bryan Johnson · Zinc · uses
- Takes 15 mg of Zinc in the morning for longevity.
- Takes 5000 IU of Vitamin D3 in the morning for general health.
- Takes 5000 IU of Vitamin D3 in the morning for general health.
- Mentions that the sunlight assessment claims low vitamin D levels cause the immune system to misfire, and notes that their vitamin D has been measured.
- Takes 5000 IU of Vitamin D3 in the morning for longevity.
- He takes 5000 IU of Vitamin D3 in the morning for general health.
- Takes 5000 IU of Vitamin D3 in the morning for general health.
- Takes 5,000 IU of Vitamin D3 in the morning for longevity.
- Takes 15 mg of Zinc in the morning.
- Takes 5,000 IU of Vitamin D3 in the morning.
- Takes 5,000 IU of Vitamin D3 in the morning.
- He takes 5000 IU of Vitamin D3 in the morning for general health.
- Takes 15 mg of Zinc 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.
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.
- Lists vitamin D as one of her staple supplements.
- Notes that several studies show patients taking vitamin D can reduce TPO levels and prolong the honeymoon period of Hashimoto's disease.
- States that in mouse studies, there was a combined effect of alpha ketoglutarate with vitamin D for both sexes.
- Uses vitamin D as an example of how people might dismiss its efficacy due to failed clinical trials that didn't adjust the dose or measure levels.
- In mouse studies, Peter Attia's team found a combined effect of AKG with Vitamin D for both sexes.
- Suggests that supplementing with lots of vitamin D might help overcome the negative effects of phenytoin on bone health by improving calcium absorption, though he is unaware of studies on this.
- Recommends Vitamin D3 as one of the 'big three' micronutrients for bone health, suggesting a daily intake of 800 to 1,000 IU, which can be obtained through sunlight or supplementation.
- Suggests that supplementing with lots of vitamin D might overcome the negative effects of phenytoin on bone health by counteracting increased catabolism of vitamin D and subsequent decreased calcium absorption.
- 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.
- Recommends vitamin D for people who tend to be vitamin D deficient, such as those living in Portland, Oregon.
- Discusses evaluating vitamin D, understanding deficiency, and optimal levels.
- 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.
RAL Summary
Members OnlyTier 4 for Immune Health
Zinc at a full dose may shorten colds but does not prevent them, vitamin C is below the studied dose, and there are no counted reviews, so the evidence stays emerging [1][6].
- Emerging: not enough evidence to rank higher yet.
- Vitamin C: below the dose that worked in studies
Where the evidence disagrees: 18 of the 51 human studies found no effect.
More Details
Members OnlyBody systems · Combine with · Possible side effects
Body systems: Immune system, Respiratory system
Combine with: For immune support, zinc pairs well with vitamin C, vitamin D3, and elderberry. Quercetin can help zinc uptake into cells, and copper (1-2 mg) can offset the copper depletion that comes with prolonged zinc use. Take lozenges with or after food to reduce nausea. If heartburn relief is the actual goal, choose a separate fast-acting product such as calcium carbonate chewables, an alginate (sodium alginate) formula, or magnesium hydroxide. For longer-term support, consider DGL licorice, zinc-carnosine (a different form of zinc studied for gastric lining support), or aloe vera. If heartburn is frequent or persistent, consult a healthcare provider.
Possible side effects: Zinc taken for colds caused more mild side effects than placebo in a large review. The one readable review mentioned no side effects.
Supplement Facts
Vitamin C 30 mg · Vitamin B6 2 mg · Zinc 25 mg
Supplement Facts
Serving Size 1-3 Lozenge(s)
Servings Per Container 90
Amount Per Serving% Daily Value
| Vitamin C | 30 mg | |
| Vitamin B6 | 2 mg | |
| Zinc | 25 mg | |
| Proprietary Blend | 22 mg | † |
† Daily Value not established.
Other ingredients: Dextrose, Fructose, Sorbitol, natural Fruit flavor, Vegetable Stearic Acid, Silica, Vegetable Magnesium Stearate.
Directions: Directions: As a dietary supplement, take 1 to 3 lozenges daily. Keep lozenge in mouth until dissolved.
Label source: NIH label database · Report a label change
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Graded November 7, 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.
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