Kirkland Signature Calcium 600 mg with Vitamin D3 Review
Kirkland Signature Calcium 600 mg. with Vitamin D3, 500 Tablets (2 Pack), sold on Amazon under the brand KIRKLAND. The listing describes the item form as tablet, with a primary supplement type of calcium and vitamin D3, and states it is unflavored and intended for adults. The item details list a bottle container type, a number of items of 2, a unit count of 2 count, and a manufacturer part number of 389194. The bullet points state Calcium Carbonate 600 mg., Vitamin D3 400 IU, and USP Verified. The product description section repeats Calcium Carbonate 600 mg. Vitamin D3 400 IU USP Verified. The listing shows the product as currently unavailable, with no date given for when or if it will return to stock. The ASIN is B06WD4VC8N and the product was first available on Amazon on January 31, 2017. The listing ranks number 187,344 in Health and Household and number 928 in Calcium Mineral Supplements. The page carries a legal disclaimer that statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition. The item dimensions are 3.5 x 3.5 x 7.5 inches and the weight is 4.1 pounds.
Study, Trial or Testing Result Summary
Members Only25 human studies · 7 improved
The evidence for calcium with vitamin D for bone health is mixed. A large review of eleven trials in women with thinning bones after menopause found that calcium plus vitamin D modestly improved pelvic bone density but not spine or hip density, and did not reduce fractures [1]. Two small older trials of 1 gram and 1,200 milligrams of calcium a day found no clear gain in bone mineral [2][3]. Surveys linked more dietary calcium in food with denser bones, in one case only in women [4][5], but a six-year study found dietary calcium unrelated to bone loss [6]. This tablet has 600 milligrams of calcium, below the 1,000 to 1,200 milligrams studied unless two are taken. Its vitamin D is 10 micrograms, or 400 units, which is below the studied dose: a review of older adults found that 700 to 800 units a day cut hip fractures by 26%, while 400 units a day did not help [7]. Another review of nine studies found no clear drop in fractures with vitamin D [8], and a review in women without thinning bones could not confirm fewer fractures [9]. Animal and cell studies are never counted.
See all 25 studies →Hide the studies
- In 11 trials of 43,869 postmenopausal women with osteoporosis, calcium plus vitamin D modestly improved pelvic bone density but not spine, neck of femur or total hip density, and did not reduce fractures.The effects of combined calcium and vitamin D supplementation on bone mineral density and fracture risk in postmenopausa…
- This review of smartphone apps for osteoporosis self-management did not test vitamin D supplements and found no significant effect on vitamin D intake.Digital Health Technologies for Long-term Self-management of Osteoporosis: Systematic Review and Meta-analysis.
- In trials of older adults, 700 to 800 IU a day of vitamin D cut hip fracture risk by 26% and other nonvertebral fractures by 23%, while 400 IU a day gave no significant benefit.Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials.
- Across nine studies, vitamin D3 did not significantly reduce nonvertebral or vertebral fractures versus placebo or calcium alone, with only a borderline trend toward fewer falls.The effect of cholecalciferol (vitamin D3) on the risk of fall and fracture: a meta-analysis.
- In 23 trials of 1,209 kidney transplant recipients, vitamin D analogues (2 trials, 51 patients) improved lumbar spine and femoral neck bone density versus no treatment, but no trial showed fewer fractures.Interventions for preventing bone disease in kidney transplant recipients: a systematic review of randomized controlled …
- In 18 small trials of 576 children with chronic kidney disease, vitamin D preparations lowered parathyroid hormone levels, but there were few data on growth or bone deformities and no clear differences between preparations.Interventions for metabolic bone disease in children with chronic kidney disease.
- One small trial of 39 people with sickle cell disease found vitamin D3 for six weeks raised blood vitamin D and reduced pain days versus placebo, but no bone outcomes were reported and the evidence was low quality.Vitamin D supplementation for sickle cell disease.
- In nine trials of postmenopausal women without osteoporosis, vitamin D raised blood vitamin D and improved some bone remodeling measures, but only one study found fewer fractures, so a fracture benefit could not be confirmed.Supplementation of vitamin D isolated or calcium-associated with bone remodeling and fracture risk in postmenopausal wom…
- In a review of 25 observational studies of healthy men aged 50 or older, evidence linking calcium intake to bone density or bone loss was inconsistent or weak.Risk factors for low BMD in healthy men age 50 years or older: a systematic review.
- In 500 elderly women with Alzheimer disease who all took 1000 IU of vitamin D2 plus calcium, adding risedronate for 18 months raised bone density 4.1% and cut hip fracture risk compared with placebo, but vitamin D itself was not tested alone and the paper was retracted.The prevention of hip fracture with risedronate and ergocalciferol plus calcium supplementation in elderly women with Al…
- Children whose mothers took 1000 IU of vitamin D3 daily during pregnancy had higher whole-body bone mineral content and density at ages 6-7 than children whose mothers took placebo.Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled…
- In 242 elderly men with Parkinson disease who all took 1000 IU of vitamin D2, adding risedronate for 2 years raised bone density, but vitamin D was not compared against placebo and the paper was retracted.Risedronate and ergocalciferol prevent hip fracture in elderly men with Parkinson disease.
- In 39 older women with severe osteoporosis, 1200 mg of calcium daily with or without 25-hydroxyvitamin D for two years kept bone mineral content stable in both groups, with improved bone mineralization rate in both groups.Histomorphometric effects of calcium or calcium plus 25-hydroxyvitamin D3 therapy in senile osteoporosis.
- In 40 postmenopausal women with wrist fracture, 1 g of calcium daily for one year had no significant effect on femur bone mineral content compared with placebo.Bone mineral content in women with Colles' fracture: effect of calcium supplementation.
- In 2904 US adults aged 60 and over, higher dietary calcium was linked with higher lumbar bone density, but this link held in women and not in men.Association between Dietary Calcium Intake and Bone Mineral Density in Older Adults.
- In 1479 elderly Japanese men, greater milk intake was linked with higher hip and femoral neck bone density and lower bone turnover, though this link weakened after accounting for calcium intake.Greater milk intake is associated with lower bone turnover, higher bone density, and higher bone microarchitecture index…
- In 1098 adults aged 65 and over, higher dietary calcium intake was linked with higher bone density at the hip and spine, while higher urinary sodium was linked with lower bone density.Dietary intake, blood pressure and osteoporosis.
- In 698 placebo-group women over 65 with osteopenia, averaging 886 mg of dietary calcium a day over 6 years, calcium intake was unrelated to bone loss at any site.Dietary Calcium Intake and Bone Loss Over 6 Years in Osteopenic Postmenopausal Women.
- In a survey of 452 women in Alaska, dietary calcium intake was low (about 306 mg a day on average), but the survey did not test calcium supplements, so it shows no effect of calcium on bone.Risk factors for osteoporosis in Alaska Native women: a cross-sectional survey.
- In Tuscany, Italy, most people who broke a hip from 2011 to 2015 were not taking vitamin D supplements, and only 30-35% were on cholecalciferol one year after the fracture; no bone outcome was measured against a comparison group.The use of cholecalciferol in patients with hip fracture.
- Among 173 adults aged 35 to 50, about a quarter had osteopenia; bone density correlated with exercise in women and in the opposite direction in men, and no calcium-specific result was reported.Bone Mineral Density Among Men and Women Aged 35 to 50 Years.
- In a 2-year cross-sectional study of 116 pre- and post-menopausal obese and non-obese women, daily vitamin D and calcium intake was low and osteoporosis was less common in obese women, though blood vitamin D levels were within normal range.Dietary Pattern and Bone Health in Pre and Post-menopausal Obese Women.
- In 52 Parkinson's patients compared with 52 matched controls, lower bone density was seen, and insufficient calcium intake was among the factors related to low bone density.Prevalence and risk factors of osteoporosis in patients with Parkinson's disease.
- In 70 people taking meds, a dedicated bone clinic found many with bone loss; early results showed bone density rose 3 to 5 percent with drug and lifestyle measures, including calcium and/or vitamin D in 44 people.Read the study on PubMed (10678299) →
- In 42 Iranian adults with hemophilia, low bone density was very common, and only cigarette smoking was significantly linked to it, not calcium intake.Bone mineral density in hemophilia patients.
Review Totals and Summary
Members Only2,321 reviews · 95% positive
Across Walmart and Costco, this calcium tablet carries about 2,321 ratings and is mostly well liked. Buyers praise the price and the easy-to-swallow tablet, but some report a recent change in texture and a few had problems with size or side effects. **What buyers say it did for them:** Several people took it on a doctor's advice for bone health. One said, "After 1 yr. of taking Kirkland Signature Calcium + D I was recently test and no signs of osteo." Another, aged 74, wrote "It's doing the job" and said her doctor reports excellent bone strength. Some can't judge results yet: one buyer with bone density problems won't know if it works until her next test. These are personal reports, not proof the tablet caused the outcome. **What they complain about:** The biggest complaint is a change in texture. One long-time buyer said the latest bottle was "a lot rougher, not smooth coated like all the other batches," and a sister had the same problem. Another said the newer pills seem "chalkier" and "MUCH more difficult to swallow." One reviewer found the large pills caused constipation and returned them. At Walmart, one buyer was sent a bottle of fish oil instead of the calcium. One long-time buyer also complains that the warehouse stores no longer carry it, so it is online only. **Taste, smell, pill size and form:** These are large tablets, about 1¼ inches according to one reviewer. Opinions on swallowing are split. One buyer called it "very smooth, and with rounded ends," and another found it "very easy to swallow in spite of the size," despite swallowing difficulties with other tablets. A reviewer who tested it in vinegar said it dissolved in under 20 minutes. Another liked that it has gone from pink to white, while a different reviewer likes the pale pink color for telling it apart from other supplements. No one mentions taste or smell. This summary covers the tablets only; reviews of other forms were left out. **Value for money:** Price is the most common positive. Walmart buyers wrote "Excellent price. Excellent quality." and "Lowest I could find." Another got it "at a good price, compared to other brands." The Costco story differs: a long-time buyer says it is now online only "for double the price," though Costco's reply says the online price includes shipping and handling, while warehouse items are listed at a cash-and-carry price. **Who it seems to suit and who it did not:** It seems to suit people whose doctors recommended calcium with D and who want a low-cost option, including some who normally struggle with tablets. One reviewer liked that it has no added magnesium. It suited some less well: people sensitive to large pills, one who got constipation, and those who received the rougher-textured batch. One reviewer felt the warehouse alternative, a calcium citrate/magnesium/zinc tablet, has too low a dose for seniors or people with osteopenia, so this carbonate tablet was their preference. Many Walmart reviews are marked as incentivized, and most come from third-party sellers.
Biohacker Summary
Members Only8 of 10 recommend it
Vitamin D, the main ingredient here, gets a strong thumbs up from the panel: all ten spoke about it, and most either recommend it or take it themselves. People take it for immune support, brain health and mood, bone strength, heart health, muscle, and male fertility, and several say most people run low, especially in fall and winter or when sun exposure is limited. The preferred form is vitamin D3, often paired with K2 (and magnesium for bone health), and it is best taken with dietary fat for absorption. Doses range from 5000 IU a day, which four of them take in the morning, up to 10,000 IU or more from one panelist, and many urge testing blood levels, with targets from about 40 up to 100 ng per ml. One panelist cautions there is little point in supplementing for most goals unless you are deficient, and another says to avoid taking it in the morning with other supplements; calcium, a smaller ingredient in this product, came up only once, as a food source mention.
See all 10 biohackers →Hide the biohackers
Dr. Eric Berg · Vitamin D · warns
- 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.
- 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.
- Warns that bone loss cannot be fixed with just calcium, as bone is primarily collagen with other essential minerals.
- States that a lack of vitamin D can potentially cause achy bones or crashing mood.
- States that vitamin D is intimately involved in the immune system and recommends taking at least 10,000 IUs each day.
- States that taking high doses of vitamin D3 for 14 days can improve mood, sleep, low back pain, skin issues, and blood pressure, as well as act as a natural anti-inflammatory and reduce susceptibility to sickness.
- Mentions that grass-fed liver has vitamin D.
- Dr. Berg includes calcium carbonate among the synthetic supplements to avoid.
- Warns against calcium carbonate, also known as limestone, stating that while it lowered hip fractures in a study, it also increased kidney stones and is not good for arteries, requiring the body to work hard to use it.
- Notes that tannins in tea bind calcium, blocking its absorption.
Dave Asprey · Vitamin D · uses
- Takes Vitamin DAKE from Suppgrade Labs.
- Suggests that vitamin D supports brain health, muscle function, and focus.
- 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.
- 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.
- 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.
- 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.
- Takes Vitamin DAKE from Suppgrade Labs because D3, A, K2, and E work together.
- Mentions taking vitamin D in the morning, comparing it to the daily dosing of testosterone.
- Notes that when energy intake is too low for training demand, nutrient intake often falls short, especially for calcium, which is associated with reduced bone health.
- Explains that calcium provides the raw material for bones, but it isn't a standalone input and needs a whole system to be effective.
- Notes that people take calcium for their bones.
- Warns that taking calcium without vitamin D, A, and K2 can lead to calcium going into tissues, causing bone spurs and other issues, and recommends a two-to-one ratio of calcium to magnesium.
Siim Land · Vitamin D · recommends
- 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.
- States that Vitamin D connects biology to light and that UVB reaching the skin enables its production.
- Lists dairy and sardines as sources of Calcium.
- 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.
- 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.
- Notes that Boron reduces calcium/magnesium loss.
- Recommends Vitamin D because microglia contain Vitamin D receptors, and Vitamin D helps keep the immune system properly regulated, with low levels associated with greater neuroinflammation and a higher risk of autoimmune conditions.
- Recommends a high calcium intake for bone health.
- Places calcium supplementation in the 'bad tier' due to its association with increased cardiovascular events, recommending dairy or bones as easier ways to get calcium, though it can be useful for postmenopausal women with low bone density.
Ben Greenfield · Vitamin D · recommends
- 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 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.
- Has been taking Vitamin D3 K2 for over a decade.
- Notes that sunlight influences more than just vitamin D production.
- Recommends keeping vitamin D levels high, suggesting that a supplement is probably not a bad idea, especially given that many people are deficient due to spending most of their time indoors.
- Recommends getting enough vitamin D for blood pressure management.
- Recommends optimizing vitamin D levels to a serum score of around 50 to 80 nanograms per milliliter, as deficiency is linked to tinnitus volume and can assist with it.
- Recommends using hormone building blocks like vitamin D for hormone optimization.
- Is considering whether he needs a calcium supplement because lead can displace calcium in bones, affecting bone strength.
- Notes that vitamin D deficiency is the most common deficiency.
- Mentions calcium as a common deficiency.
- Recommends adequate intake of calcium for bone strength.
- Is using calcium chloride mixed with PRP before injecting for the P-shot.
Dr. Mark Hyman · Vitamin D · recommends
- 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 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.
- 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.
- Notes that rickets, which causes terrible bone deformities, is caused by vitamin D deficiency.
- Notes that vitamin D is an important nutrient for brain performance and aging, and that many people have gaps in these nutrients.
- Notes that calcium is in bones but is also essential for nerves, muscles, and the heart, and low levels can affect muscle function and heart rhythm.
- States that green leafy vegetables are great sources of calcium.
- Notes that calcium needs are lower than advertised and that stress, soda, and excess sugar can drive calcium loss.
- Does not prescribe calcium supplements at all, teaching people to get it from whole foods instead, because calcium supplements don't work for building bones or preventing fractures, and it's bone quality, not density, that matters.
Thomas DeLauer · Vitamin D · uses
- 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 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.
- 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.
- Notes that milk contains 120mg of calcium, while sardines contain 351mg, highlighting a 3x difference.
- Recommends getting vitamin D, suggesting it can be obtained while walking.
- States that vitamin D is best obtained from the sun, but getting it from food definitely helps, and notes its role as a hormone influencing many cells.
- Recommends D3, suggesting a dose of 2000-4000 IU, and notes that MK-7 slowed bone loss over three years.
- Recommends vitamin D, especially for Hashimoto's, explaining that it drives T reg expansion to suppress autoimmune responses that attack the thyroid, and notes that vitamin D and selenium deficiencies often co-occur.
- Recommends getting calcium, along with vitamin D, zinc, and magnesium, from foods like sardines, as they are important for inflammatory pathways in the gut.
- Explains that eating sardines with their soft bones provides a serious hit of calcium, which is a perfect combination for bones and may contribute to satiety.
- Mentions that magnesium and calcium should not be taken together as they cancel each other out.
Bryan Johnson · Vitamin D · uses
- 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 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.
- Recommends calcium as a mineral that, along with phosphorus, magnesium, and boron, is deposited to fortify the bone structure after the collagen scaffold is in place.
- Agrees that a little extra calcium is probably okay, especially for women, to really hit home for bone mineral density.
- Recommends prioritizing calcium intake for postmenopausal women to help maintain bone density and reduce the risk of osteoporosis.
- Bryan Johnson takes Calcium daily as part of his Longevity Mix, which supports healthy bones and teeth.
Dr. Rhonda Patrick · Vitamin D · neutral
- 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 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.
- 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.
- Mentions that kale delivers calcium, a micronutrient many diets fall short on.
- 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.
- Notes additional gaps in calcium.
- Reports that alcohol use disorder is associated with a 20-50% greater prevalence of Calcium deficiency.
- Around 38% doesn't meet the requirement for calcium.
Andrew Huberman · Vitamin D · neutral
- 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.
- 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.
- Takes 5000 IU of Vitamin D3 in the morning.
- He takes 5,000 IU of Vitamin D3 in the morning for overall health.
- Takes 5000 IU of Vitamin D3 in the morning.
- Takes 5,000 IU of Vitamin D3 in the morning for general health.
- Takes 5000 IU of Vitamin D3 every day for longevity.
- Takes 5,000 IU of Vitamin D3 in the morning.
- Discusses "hard water" and the role of magnesium and calcium in cardiovascular health.
- Adequate intake of calcium is vital for bone health.
Peter Attia · Vitamin D · uses
- 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.
- Recommends calcium as one of the 'big three' micronutrients for bone health, suggesting a daily intake of 1,000 to 1,200 milligrams, which can be supplemented with calcium carbonate or calcium citrate.
- 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.
- Explains that bone is 50 to 70% mineral, predominantly calcium, and that virtually all of the body's calcium is contained within bone, making bone important for calcium homeostasis.
- 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.
- Recommends calcium for bone health, stating that teenagers probably need about 1000 milligrams a day.
- Discusses bone acting as a reservoir for calcium and how resorption and formation release calcium into the blood when needed.
RAL Summary
Members OnlyTier 4 for Bone Health
The tier 2 grade rests on an observational survey linking dietary calcium with bone density, not on a trial of calcium tablets, while the trials themselves are mixed, and the vitamin D dose was read as 20 mcg when the label gives 10 mcg (400 units), the dose a review found did not help. So it is graded Tier 4, lower than the rules alone gave.
- Emerging: not enough evidence to rank higher yet.
Where the evidence disagrees: 9 of the 25 human studies found no effect.
More Details
Members OnlyBody systems · Combine with · Possible side effects
Body systems: Skeletal system
Combine with: For its true purpose of bone health, pair this with vitamin K2 (MK-7) to help direct calcium into bone, and magnesium (glycinate or citrate) which is needed for vitamin D activation and bone mineralization. Take calcium carbonate with meals for best absorption and split doses if taking more than 500-600 mg at once. Collagen peptides and weight-bearing exercise can add bone support. If the real goal is blood sugar support, look at separate products with ingredients such as berberine, chromium, alpha-lipoic acid, cinnamon extract, or magnesium, and talk to a doctor first, especially if you take meds.
Possible side effects: No major side effects reported.
Supplement Facts
Vitamin D3 10 mcg · Calcium 600 mg
| Vitamin D3 | 10 mcg | |
| Calcium | 600 mg |
Other ingredients: Calcium Carbonate, Cellulose Gel, Maltodextrin, Croscarmellose Sodium, Magnesium Stearate, Titanium Dioxide, Polyethylene Glycol, Triethyl Citrate, Polysorbate 80, Corn Starch, Gelatin, Yellow 6 Lake, Vitamin D3.
Directions: When to take Anytime Take twice daily with a meal Suggested Use: Take one tablet two times daily, preferably with a meal.
Label source: NIH label database · Report a label change
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Where to Buy
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Graded November 4, 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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