Product Guides / Supplements & Nutrition
Calcium and Vitamin D for Bone Health Guide
Humanic Blue’s Longevity365 guide: A calcium number on the front of a bottle does not tell you how many pills supply it. These five labels differ in calcium form, vitamin D, vitamin K and swallowing format; one contains no calcium at all.
Explore the productsQuestions about living longer need evidence about lifespan, rather than a product label, a measurement or a marketing promise. This comparison separates those questions from questions about symptoms, function and daily experience.
01 / Our approach
How did we evaluate these products and services?
We read the named US product labels and official listings, comparing the amount in one labeled serving, the number of tablets, caplets, drops or chews in that serving, and ingredients that affect medication or allergy discussions. Checks are dated 16 October 2026; retail prices can differ from direct-sale snapshots.
Calcium and Vitamin D for Bone Health: evidence and sources02 / The takeaways
What did the source evidence show?
- Caltrate and Nature Made each list 600 mg calcium per tablet; Citracal Petites lists 400 mg per two caplets.
- Thorne’s D/K2 liquid contains no calcium. Viactiv adds K1, milk, soy and sugar; vitamin K matters with warfarin-type medicines.
- Product contents and quality marks do not establish fracture prevention or longer life. The companion article explains why the population and clinical reason for supplementation matter.
What does the research tell us about these offerings?
The NIH Office of Dietary Supplements distinguishes calcium carbonate, usually taken with food, from citrate, which is less dependent on stomach acid. Label serving amounts are not the same as a person’s total daily need: food, other supplements, kidney health and medicines also enter that assessment. NIH calcium fact sheet
USP is the United States Pharmacopeia, a standards and verification organization. USPSTF is the US Preventive Services Task Force, which evaluates preventive care. They do different jobs. A quality mark does not overturn the prevention limits described in the companion article or establish that these retail products help people live longer. Nature Made’s explanation of its USP marks
What changes when the amount in a serving is considered alongside the product’s actual ingredients?
The products and services
What is distinct about each product or service?
These exact products and services are compared for a specific reader goal. The order is not a ranking, recommendation or endorsement.
Amounts below describe one labeled serving, not a prescribed daily intake. Vitamin D is shown in micrograms (mcg) and international units (IU), as on the labels.
Product 01 / 05
Caltrate 600+D3
Label serving600 mg calcium + 20 mcg (800 IU) vitamin D3 per tablet
Haleon’s current Caltrate 600+D3 label lists one tablet as a serving, supplying 600 mg calcium as calcium carbonate and 20 mcg (800 IU) vitamin D3. This is the plain 600+D3 tablet, not the separate Plus Minerals or gummy formula.
The manufacturer directs adults to take it with food. The NIH explains that calcium carbonate depends more on stomach acid for absorption than calcium citrate. That distinction concerns absorption; it does not show this brand prevents more fractures. Caltrate links to retail stockists rather than quoting one direct-sale price.
Product 02 / 05
Citracal Petites with Vitamin D3
Label serving400 mg calcium + 12.5 mcg (500 IU) vitamin D3 per 2 caplets
Bayer lists two Citracal Petites caplets as a serving: 400 mg calcium as citrate and 12.5 mcg (500 IU) vitamin D3. The smaller caplet format therefore does not mean one caplet supplies the full labeled serving.
Bayer says this citrate product can be taken with or without food. Its labeled directions use two caplets twice a day—four caplets in that schedule—not two in total. Those are the seller’s directions, not an individual calcium requirement. Retail prices depend on bottle size and seller.
Product 03 / 05
Nature Made Calcium 600 mg with Vitamin D3
Price snapshot$8.59 for 60 tablets; one-time US listing, 16 October 2026
Nature Made’s Calcium 600 mg with Vitamin D3 tablet supplies 600 mg calcium and 10 mcg (400 IU) vitamin D3 per one-tablet serving. Its vitamin D amount is half Caltrate’s labeled amount, while their calcium amounts are the same. That is a label comparison, not evidence that either is better for a particular person.
Nature Made displays the United States Pharmacopeia (USP) Verified mark for this exact tablet. The mark concerns contents, specified contaminants, breakdown and manufacturing quality; it does not establish fracture prevention. Its optional subscription is a recurring purchase, separate from the one-time price.
Product 04 / 05
Thorne Vitamin D/K2 Liquid
Label servingNo calcium; 25 mcg (1,000 IU) D3 + 200 mcg K2 per 2 drops
Thorne’s Vitamin D/K2 Liquid is not a calcium supplement. Its two-drop serving supplies 25 mcg (1,000 IU) vitamin D3 and 200 mcg vitamin K2, with no calcium listed. It cannot replace the calcium amount in the other rows.
Thorne warns that vitamin K interferes with warfarin-type anticoagulants. The NIH likewise identifies a potentially serious interaction between vitamin K supplements and these blood thinners. Adding K2 is therefore a medication question, not simply an extra bone-health ingredient.
Product 05 / 05
Viactiv Chocolate Calcium Chews
Label serving650 mg calcium + 12.5 mcg (500 IU) D3 + 40 mcg K1 per chew
Viactiv’s milk-chocolate label lists one chew with 650 mg calcium as carbonate, 12.5 mcg (500 IU) vitamin D3 and 40 mcg vitamin K1. The chew also contains 1 gram of added sugar, milk and soy. This is a chewable alternative to swallowing tablets, with different ingredients to account for.
The vitamin K warning also matters here: K1, as well as K2, can interact with warfarin-type medicines. Viactiv links to retail sellers rather than giving one direct-sale price. The comparison uses amounts per chew, so it does not confuse pack size with the nutrient serving.
How does distinguishing a calcium product from a product containing vitamin D and K2 but no calcium change a bone-health comparison?
Reader Questions
A few questions to consider while reading the evidence.
- Which label difference became clearer when the number of pills or chews was included?
- How does a contents-verification mark answer a different question from a fracture-prevention study?
Extra Insights & Sources
For readers who want the evidence and comparison details behind this guide.
Product comparison matrix
How do the products and services compare?
This matrix summarizes the product profiles above. Amounts describe the named label or service, not a personal treatment plan. It is not a scorecard or ranking.
| Question | Caltrate 600+D3 | Citracal Petites with Vitamin D3 | Nature Made Calcium 600 mg with Vitamin D3 | Thorne Vitamin D/K2 Liquid | Viactiv Chocolate Calcium Chews |
|---|---|---|---|---|---|
| Labeled serving | 1 tablet | 2 caplets | 1 tablet | 2 drops | 1 chew |
| Calcium in that serving | 600 mg calcium (as carbonate) | 400 mg calcium (as citrate) | 600 mg | None listed | 650 mg calcium (as carbonate) |
| Vitamin D3 in that serving | 20 mcg / 800 IU | 12.5 mcg / 500 IU | 10 mcg / 400 IU | 25 mcg / 1,000 IU | 12.5 mcg / 500 IU |
| Vitamin K and relevant distinction | None listed | None listed | None listed | 200 mcg K2; warfarin interaction | 40 mcg K1; milk, soy and added sugar |
Sources
- Calcium and Vitamin D for Bone Health
- Haleon current Caltrate 600+D3 tablet label
- NIH vitamin K interaction context
- Nature Made USP product list
- Caltrate 600+D3 — official listing
- Citracal Petites with Vitamin D3 — official listing
- Nature Made Calcium 600 mg with Vitamin D3 — official listing
- Thorne Vitamin D/K2 Liquid — official listing
- Viactiv Chocolate Calcium Chews — official listing
Image credits
Disclosures
Manufacturer descriptions and benefit claims are attributed to their sources. Inclusion is not an endorsement or a personal treatment recommendation.