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Verified by IngredientMD/Citracal/Maximum Plus D3
VERIFIED BYingredientMD

Maximum Plus D3.

Strong evidence, strong doseCitracal, verified Oct 2026Formula verified. Independently reviewed.Independent review. Not commissioned by Citracal.

Calcium is the lead active here, studied most for bone strength. 13 human studies on Calcium back this formula, each one cited. Each serving carries 650 mg of Calcium, inside the range the published research used. Who it fits: skews toward women, adults.

Full label disclosure
6Active ingredientsWell studiedResearch base77Human studies
Maximum Plus D3Verified by IngredientMD
CitracalIngredientMD
The verdict
Strong evidence, strong dose
For Skews toward women, adults.
How we verify

The brand submits the formula. We read the supplement facts panel and weigh dose, form and synergy against the clinical evidence. Labs test. IngredientMD verifies. The fee pays for review time, never for the outcome.

The formula
Vitamin D3: Bone strengthExtensively studied
Calcium: Bone strengthKey driver
Zinc: Tissue repairExtensively studied
Copper: Collagen and connective tissueWell studied
Manganese: Bone strengthWell studied
Sodium: HydrationWell studied

How we read this product

Source: Supplement facts
Supplement Facts panel for Maximum Plus D3
  1. 01
    We read the label.

    The panel on the left is the one we evaluated, line by line.

  2. 02
    Every active, separately.

    All 6 actives checked against the clinical evidence: dose, form, and what the research actually shows.

  3. 03
    Then the formula as a whole.

    Doses, ratios, and how the ingredients work together. That assessment is the verdict above: "Strong evidence, strong dose".

  4. 04
    Earned, not bought.

    The verdict is public and identical whether or not a brand pays. A formula that does not clear the bar gets nothing.

Read by the engine against 2.1 million data points from clinical trials, PubMed and more than a hundred vetted sources. No individual reviewer is named or implied.

The receipts

Well studied
Research base
77
Human studies
650 mg
Calcium
1000 iu
Vitamin D3
650 mg per serving sits inside the studied 500 mg-1 g range
Calcium, NIH ODS + USPSTF 2018 + WHI calcium trial

Cross-checked against 2,337 documented interactions for these actives.

Read the evidenceVitamin D3, the evidence →Calcium, the evidence →Zinc, the evidence →Copper, the evidence →Manganese, the evidence →Sodium, the evidence →

Inside the formula

Vitamin D3
20 studies
Bone strength
Extensively studied
Calcium
13 studies
Bone strength
Studied 500 mg to 1.5 g a day
Key driver
Zinc
22 studies
Tissue repair
Extensively studied
Copper
Collagen and connective tissue
Well studied
Manganese
Bone strength
Well studied
Sodium
11 studies
Hydration
Well studied
In context

The gap this formula speaks to.

Public health figures the engine matched to this formula's ingredients. Reported by their source, cited and dated, never written by the brand.

This formulaNHANES 2017-2018, published 2021

57.6%

During 2017 to 2018, 57.6% of US adults aged 20 and over reported using a dietary supplement in the past 30 days.

CDC National Center for Health Statistics
25 more
Daily use

59 to 66 days

was the median time it took adults to make a new daily health habit automatic across the studies a 2024 review pooled, with individuals ranging from 4 to 335 days.

Systematic review and meta-analysis, 2024
Calcium

Meta-analysis, 2007

In adults 50 and older, calcium with or without vitamin D slowed bone density loss by about 0.5% at the hip and 1.2% at the spine.

The Lancet
Calcium

Randomised trial, 2025

Calcium taken around prolonged load carriage lowered blood markers of bone calcium loss compared with placebo. These are markers, not measured bone outcomes.

Randomised trial
Vitamin D3

Meta-analysis, 2024

Across 10 trials in 318 athletes, vitamin D3 raised blood vitamin D by about 14.8 nmol/L and hinted at better muscle strength, though few trials leave that uncertain.

Frontiers in Nutrition
Vitamin D3

Randomised trial, 2025

Vitamin D3 supplementation changed the inflammatory protein CHI3L1 and oxidative stress markers in adults with a chronic demyelinating condition. These are markers, not clinical outcomes.

Neuropsychopharmacology Reports
Vitamin D3

Meta-analysis, 2024

Across 20 studies, daily vitamin D3 raised blood vitamin D levels by about 10.4 nmol/L more than the same dose of vitamin D2, roughly 40 percent more.

Advances in Nutrition
Sodium

Systematic review, 2026

A systematic review catalogued gastrointestinal symptoms reported across sodium bicarbonate dosing protocols and described how symptom burden varies with dose, timing and whether the dose is split or given with food.

European Journal of Sport Science
Calcium

Meta-analysis, 2024

In adults with excess body weight, calcium supplementation produced small reductions in body weight and body fat compared with placebo.

Meta-analysis
Sodium

Randomised trial, 2026

Microencapsulated sodium butyrate was tested against abdominal symptom scores and carbohydrate metabolism markers in adults with high blood sugar. Again a butyrate trial in which sodium is the carrier salt.

Scientific Reports
Vitamin D3

Meta-analysis, 2014

Across 23 trials of 4,082 adults, vitamin D raised bone mineral density at the femoral neck by about 0.8%, with no measurable change at the spine, hip, or other sites.

Lancet
Calcium

Cohort study, 2025

Seminal fluid phosphate concentration was linked with semen quality measures but did not track with supplement intake. An association between two measurements, not a cause.

European Journal of Endocrinology
Sodium

Randomised trial, 2026

A randomised trial tested an algorithm-driven sodium supplementation protocol against usual care and measured growth in infants born preterm.

Pediatrics Open Science
Calcium

Randomised trial, 2024

Two randomised trials compared a lower daily calcium dose with the higher standard dose in pregnancy. The lower dose met the prespecified non-inferiority margin for one outcome but not for every outcome tested, which is a statement about margins and not a demonstration of equivalence.

The New England Journal of Medicine
Sodium

Randomised trial, 2025

In a trial of 104 very preterm infants, oral sodium supplementation raised daily weight gain by 3.6 grams per kilogram compared with placebo.

BMJ Paediatrics Open

Population figures from public health data. Context for the category, not a statement about any individual and not a claim about this product.

What this formula earned

Every one of these is a fact the engine could ground.

Each line below was derived from this formula's own record at the time of verification. Nothing here was written by the brand, and nothing can be added that the evidence does not carry.

  • Studied in people22 human studies on Zinc back this formula, each one cited.
  • A mechanism that is settledHow Vitamin D3 and Calcium work is settled pharmacology.
  • Studied together, not just separatelyVitamin D3 and Calcium have been studied together, not only separately.
  • Recent work on the recordThe most recent study on this record was published in 2026.
  • Serving amount inside the studied rangeEach serving carries 650 mg of Calcium, inside the range the published research used.
  • A stated daily maintenance amountCalcium is here at a daily maintenance amount, which is what a daily supplement is for.
  • Why this formatIt is a tablet, so the amount per serving is fixed and it stores well.
  • Full label disclosureEvery ingredient on this label carries its own declared amount.
  • Where it comes from and how it is madeVitamin D3 is made by more than one route.
  • Positions this formula already qualifies forThis formula already qualifies for positions beyond the one it is sold into, on the evidence it carries.
  • A position nobody is holding yetSome of those positions are ones almost nobody is selling to yet.
  • Interaction screen on the recordEvery active on this label was screened against the interaction record, and the screen is published with it.
What the trials show

What the trials show about timing.

Time-to-effect windows the engine read from the trial record. Each is a window a named study measured, cited and dated, never written by the brand.

  • Vitamin D3about 3 months of daily useBuilds with daily use

    In the trial record, blood vitamin D rises for about 3 months of daily vitamin D3 and then holds at a plateau, near 69 nmol/L at 1,000 IU a day, from a starting level near 41 nmol/L.

    Early
  • Calciumwithin about one to six hours of a single doseMeasured within a day

    A randomised cross-over trial in ten women of mean age 69 gave a single 500 mg dose of calcium as citrate fasting, citrate with a meal, fortified juice or a dairy product meal, with blood drawn before and at 1, 2, 4 and 6 hours. Serum ionised and total calcium increased significantly from baseline over six hours, with the rise similar after fortified juice, delayed when citrate was taken with a meal and smaller after the dairy meal. A separate double-blind cross-over trial in 25 postmenopausal women measured parathyroid hormone and a bone resorption marker 12 hours after a single calcium dose. Ten participants is a small sample, and what moved was blood chemistry, not a sensation.

    Promising
  • Zincover about five days of lozenges started within 24 hours of symptom onsetBuilds with daily use

    Across three randomised placebo-controlled trials pooled as individual patient data (199 adults with naturally acquired colds, 80 to 92 mg of elemental zinc a day as acetate lozenges), 70 percent of the zinc group had recovered by day 5 against 27 percent on placebo, and colds ran 2.73 days shorter against a 7 day average duration. A separate meta-analysis of seven lozenge trials (575 participants, doses above 75 mg a day, zinc acetate or zinc gluconate) measured cold duration 33 percent shorter, with no significant difference between the two salts.

    Strong
  • Zincabout two to four weeks of daily intakeBuilds with daily use

    In a controlled feeding study in nine healthy men, six weeks of restricted zinc intake raised DNA strand breaks in peripheral blood cells, and four weeks of repletion at 11 mg a day, with 20 mg of supplemental zinc for the first seven days, reversed the rise. In a separate randomised placebo-controlled trial in 40 Ethiopian women eating a high-phytate diet, 20 mg a day of zinc sulfate for 17 days lowered mean comet tail moment from 39.7 to 30.0 while plasma zinc did not change significantly. Both windows were measured on a DNA damage marker in blood cells, not on a symptom.

    Early
  • Copperabout four to eight weeks of daily useBuilds with daily use

    In an 8 week pilot with a parallel placebo group, 8 young women taking 2 mg of copper a day as copper glycinate showed a 9 percent mean rise in serum ceruloplasmin and a 75 percent rise in diamine oxidase, alongside a 39 percent fall in plasma F2-alpha isoprostanes. Erythrocyte copper-zinc superoxide dismutase did not change. In a separate 4 week double-blind crossover in 20 men with moderately high cholesterol at the same 2 mg a day, copper moved no measure across the whole group and raised superoxide dismutase and diamine oxidase only in the 10 men who started below the median. Both are small and both measured enzymes in blood, not a symptom.

    Early
  • Sodiumabout 3 days to 4 weeks of steady intakeBuilds with daily use

    In the excretion studies the EFSA reference opinion reviews, urinary output closely tracked dietary sodium once intake was held steady: 98% of dietary sodium appeared in 24-hour urine in a 3-day study, and 86% of sodium ingested over 4 weeks was recovered in 24-hour urine collected during the same period.

    Early
1 more
  • Sodiumabout 29 days at each fixed intake levelBuilds with daily use

    In the controlled metabolic study the EFSA reference opinion reviews, young men held at constant sodium intakes for 29 days per level showed rising average daily urinary aldosterone excretion as intake was stepped down from 4.9 g/day to 2.5 g/day.

    Promising

Windows measured in the cited trials. Context for how the active behaves over time, not a statement about any individual and not a claim about this product.

General timing

How each ingredient usually behaves over time.

Six ingredients, from each one's own page.

How each ingredient usually behaves over time, from its own page on IngredientMD. General timing for the ingredient, not a measurement of this product.

Chemical form

The same ingredient, carried differently.

What each form is, and where it fits in a formula. Measured findings carry the study that reported them.

  • Cholecalciferol (vitamin D3)

    The animal-sourced form of vitamin D, made in skin under UVB light and produced commercially from lanolin. Fat-soluble, so it travels with dietary fat and is stored in body fat.

    Fits
    Raising and holding vitamin D status, and the form most supplement trials use.
    Trade-off
    Being fat-soluble it accumulates with sustained high dosing, so intakes are set against the tolerable upper level rather than topped up freely.

    In a 12-week double-blind randomised controlled trial in 108 young women in urban Bangalore, most of whom began vitamin D-deficient, daily vitamin D3 at 400, 600 or 800 IU in a fortified wafer raised serum 25-hydroxyvitamin D, parathyroid hormone fell over time, and effects on bone-turnover markers were modest and not dose specific. The 800 IU dose brought 65 percent of participants to sufficiency.

Descriptions of the form itself, read from the cited studies. Not a comparison between products and not a statement about any individual.

Format

Tablet

It is a tablet, so the amount per serving is fixed and it stores well.

Best forHigh-dose minerals and anything needing timed or delayed release.
From the same shelf

Studied alongside this brand's other formulas

Where two of this brand's products carry actives the literature has read together, the pairing and its basis are below. The evidence word is the corpus row's own confidence, never a score.

Calcium + D3 + Maximum Plus D3Established

Zinc and copper are taken up by the same intestinal cells, and a steady high zinc intake raises a binding protein called metallothionein that holds onto copper and carries it out as those cells are shed. Formulas often include a little copper alongside zinc so that ongoing zinc use does not draw down normal copper status.

Established mineral antagonism. No combination trial has tested this exact pairing.

Calcium + D3 + Maximum Plus D3Established

Active vitamin D switches on the calcium-binding proteins and channels in the gut lining that carry calcium across the intestinal wall, so the body absorbs far more of the calcium it takes in. With too little vitamin D, much of a calcium dose passes straight through unabsorbed.

Established biochemistry. No combination trial has tested this exact pairing.

Recurring supply suggested

Because the effect builds and holds only with continued daily use, a steady recurring supply is the practical way to keep it going.

Questions shoppers ask

Is Maximum Plus D3 independently verified?
Yes. IngredientMD reviewed this formula independently and verified it in Oct 2026. The verdict is earned, not bought: brands can't edit or purchase it.
What's in Maximum Plus D3?
Maximum Plus D3 is built on Vitamin D3, Calcium, Zinc, Copper, Manganese, Sodium. Each ingredient links to its own evidence page on IngredientMD.
Were ingredient interactions checked?
Yes. The combination was screened against 2,337 documented interactions for these actives in IngredientMD's interaction database.
Who is IngredientMD?
IngredientMD is an independent supplement-science platform. We analyze ingredients and formulas against clinical research, and we verify products only when they clear our bar. Labs run the tests. We review the results.
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These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This record is not medical advice. Always consult your healthcare provider before starting any supplement regimen.

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