Tablets, whether swallowable, chewable or effervescent, are among the most common types of calcium supplements. These supplements are easy to take, moderate in cost, and can readily be included in a daily vitamin/mineral supplement regimen.
Calcium carbonate is the usual form of calcium used in these dietary supplement tablets for a variety of reasons: calcium carbonate has the highest concentration of elemental calcium, 40 percent is significantly less expensive than other calcium salts, which makes it most economical in use; and calcium carbonate is highly bioavailable.
Formulating Swallowable Calcium Supplement Tablets
The RDI (Recommended Daily Intake) of elemental calcium by adults in most countries is 1,000 milligrams of calcium per day. For optimal calcium absorption health experts recommend that the daily intake be divided into two or three smaller doses throughout the day.
The tablets should be made as small as possible for ease of swallowing. Calcium carbonate facilitates production of the smaller tablets. With its 40 percent level of elemental calcium, 2,500 milligrams of calcium carbonate will provide the needed 1,000 milligrams of calcium. In contrast, when calcium citrate is used, which is only 21 percent elemental calcium, 1.9 times as much—4,800 mg—is required to provide the same 1,000 mg of calcium.
To aid in making the smallest possible tablets, Specialty Minerals offers several types of dense and very dense precipitated calcium carbonates (PCCs), which allow maximum calcium loading in a small tablet. These products, which are made in the U.S. are:
- CalEssence® 450 and 1500 precipitated calcium carbonate, with particle sizes of 4.5 and 12 microns. All CalEssence PCC products have ultra-low levels of lead, less than 125 ppb, to make compliance with California Proposition 65 easy.
- ViCALity® Extra Heavy and Ultra Heavy PCCs, also 4.5 and 12 microns, with less than 500 ppb of lead, which allows Proposition 65 compliance in most cases.
The best product for swallowable tablets, which is made in the Specialty Minerals plant in the United Kingdom, is:
- Sturcal® L PCC – a 6 micron PCC.
Formulating Chewable Calcium Supplement Tablets
When tablets are to be chewed, packing the most calcium into the smallest space is not as great a concern, so the choice of the type of calcium carbonate is broader. When the desire is to still keep tablets to a reasonably small size, the denser grades listed above are still recommended. To that list of denser grades recommended for swallowable tablets, CalEssence 300 PCC and ViCALity Heavy PCC, both of which are 3 microns, can be added to the recommendations for chewables.
Others may prefer a larger tablet, so the use of a small particled PCC like CalEssence 70 or ViCALity Albafil® PCC, each 0.7 microns, can be recommended. As when preparing swallowable tablets, any calcium carbonate chosen must be granulated before compression into a tablet.
Formulating Effervescent Calcium Supplement Tablets
An effervescent tablet is an excellent option for consumers who don’t like to chew tablets and can’t swallow them. An effervescent tablet can be prepared with a variety of liquids—water, juice, soft carbonated beverages. Calcium carbonate is an alkali that will react with an acid, which is also included in the tablet. When the tablet is dropped into the liquid, carbon dioxide gas is formed, making the liquid bubble or effervesce. Besides being a pleasant way to take the supplement, the calcium enters the stomach dissolved so it can be more quickly absorbed. The reaction also reduces and buffers the pH of the liquid, making it more tolerable on the stomach.
Effervescents usually contain some kind of mild organic acid, such as citric, ascorbic or malic acid. Some technology is needed to manufacture and package an effervescent so it will remain stable on the shelf and may require the formulation expertise of a custom effervescent packager.
Many grades of SMI calcium carbonates can be used in effervescents. A smaller particle, such as the 0.7 micron CalEssence 70 PCC or ViCALity Albafil PCC solid particles or a slightly larger, about 2-3 micron, CalEssence 160, ViCALity Extra Light or Calopake™ Extra Light PCC needle shaped particle would be best. These PCCs have large surface areas available to react quickly with the acid, speeding up the preparation of the drink. And the small particle sizes help avoid any gritty mouth feel that could result from using a overly large particle that wouldn’t fully dissolve before ingestion.
Granulating Calcium Carbonates For Tableting
All calcium carbonates must be granulated before converting to tablets, as they have inherently poor compressibility, so are not directly compressible. This is a fundamental property of calcium carbonate, no matter the type. Granulation involves mixing the calcium carbonate with some binder such as maltodextrin, starch or acacia gum, usually at a 5 to 10 percent binder level, and then agglomerating to a larger, easier to handle particle, much like sand.
Proper granulation is critical to producing tablets with adequate strength for handling and shipping, while also being able to disintegrate and dissolve quickly in the stomach. USP requirements for calcium carbonate supplement tablets require disintegration and dissolution within 30 minutes.
Specialty Minerals’ laboratory carried out a granulation study, looking at the effect of calcium carbonate particle size and particle size distribution on the granulation process and the properties of the tablets made from the granulations. You can see this study by clicking here.
Specialty Minerals Precipitated Calcium Carbonates For Nutritional Supplement Tablets
- Details on the various grades of SMI PCCs for tablets can be seen by clicking here.
- To download a data sheet for a particular grade, click here.
All Specialty Minerals precipitated calcium carbonates are manufactured in plants registered with the U.S. Food and Drug Administration (FDA) as Drug Manufacturing Establishments, and follow Good Manufacturing Practices (GMP). These plants are also ISO 9000 quality certified.
The CalEssence and ViCALity PCC products are made in Adams, Massachusetts and are certified to meet USP and FCC requirements. The Sturcal™, Calopake™, Multifex-MM® USP, and Calofort® U PCCs are manufactured in the United Kingdom. They are certified to meet EP, USP and E170i requirements, and can be certified to meet USP / FCC, as well. All are certified Kosher, and are available world-wide.
Specialty Minerals Talcs As Tablet Glidants and Lubricants
SMI also manufactures USP talcs which are used in tableting as glidants and lubricants. Small particle sized talcs, 2 to 3 microns, are normally used. When one of these small talcs replaces a portion of the magnesium stearate that is used for lubrication, the disintegration and dissolution times impaired by the addition of magnesium stearate can be restored.
The two Specialty Minerals talcs recommended for use in tableting are MicroTalc® MP 15-38 USP talc and UltraTalc® 5000 USP talc. For further information on SMI talcs for tableting, and on a Specialty Minerals laboratory study on talc as a glidant, click here
- Specialty Minerals calcium carbonates for nutritional supplements and pharmaceuticals
- Specialty Minerals talcs for nutritional supplement tableting
- SMI Minerals Used in consumer products
- What is Precipitated Calcium Carbonate (PCC)? A mineral introductory webpage
- What is PCC for Healthcare? A downloadable information sheet
- What is Talc? A mineral introductory webpage
- Granulation Study: Effect of particle size and particle size distribution on calcium carbonate granulation
- Talc Glidant Study
- Lead in Calcium-Containing Products: California Proposition 65 A downloadable information sheet.
- Resources and useful information for formulators: Downloadable information sheets on bioavailability, economics of formulating with calcium carbonate, and effect of particle size and shape on supplement properties.
- Osteoporosis: Anyone Can Be At Risk—Even You! A downloadable information sheet
- About Specialty Minerals Inc.
- SMI Quality: Good Manufacturing Practices and Kosher Certification