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Why was the labeling of Maximum D3® changed to 325 mcg (13,000 IU)?

The Maximum D3 labeling has changed from 10,000 IU to 325 mcg (13,000 IU), but the product and formulation have not changed. The change was made because of new FDA labeling requirements. Under the new guidelines, Maximum D3 could continue to be labeled 10,000 IU (250 mcg) or 13,000 IU (325 mcg), but the 13,000 IU labeling was chosen to most accurately reflect the contents of Maximum D3.

The FDA determined that the contents of several substances, including vitamin D, should be stated in micrograms (mcg or µg) and no longer need to be in International Units (IU). The US food labeling laws apply to nutritional supplements and require that actual content for fat soluble vitamins be between 100% and 130% of the content stated on the label. Because of some possible ambiguity in the most current regulations (Federal Register / Vol. 81, No. 103 / Friday, May 27, 2016 / Rules and Regulations), we have elected to use the actual content of Maximum D3 rather than an acceptable arbitrary value. The product and formulation have not changed.

Why is Maximum D3® a superior vitamin D supplement?

Maximum D3® is high-quality, convenient, made in the USA and available OTC.  For over 15 years, customers have achieved optimal vitamin D levels while supplementing with Maximum D3®.

Maximum D3® was designed by a doctor when he was frustrated by the lack of high-quality supplements available to his patients.  Maximum D3® was carefully formulated to be high-quality, convenient and well-regulated.

Some other vitamin D supplements contain vitamin D2 (a less effective source of vitamin D), do not contain enough vitamin D to be effective and/or are not designed to be easily digested by the human body.  Additionally, testing through an independent lab has shown that some other retail vitamin D supplements have LESS dosage than stated, contain anaerobic bacteria and/or contain mold.

Maximum D3® is one of the few vitamin D preparations that has undergone INDA review by the FDA. All Maximum D3® product is tested to ensure it meets the dosing stated on the package.

Quality counts and quality is our priority!

What is the expiration date for Maximum D3®?

Please refer to the order page for the current expiration date.  

Are gummies suitable for supplements including Vitamin D supplements?

Gummies are not recommended as a suitable vitamin supplement due to degrading vitamin content over time and the potential for child poisoning. 

Gummies have become a popular vehicle for a large collection of nutritional products as well as candies. They are considered tasty and convenient. However, their suitability for many organics remains dubious. Gummies provide an aqueous environment of polymers (polysaccharides or proteins) which form complex net structures that can bind large quantities of water.  

Such an environment works for some, mostly water soluble and light stable products, BUT is generally not a suitable environment/vehicle for many complex organic compounds – either alone or as poorly chosen mixtures

A 2019 master’s thesis by an Icelandic graduate student demonstrates well the instability of vitamin D in several gummy variations. The documented efforts confirm that gummy preparations would lose about half of their potency before arriving on store or warehouse shelves. The products would then be expected to continue this degradation over time, losing half their potency about every 5+ weeks.   

Kaja Gertin Grétarsdóttir‘s well elucidated work can be found here:  (English option in top ,right corner.) 

It would be remiss not to add that many safety and medical institutions have called into question the use of gummies in the health setting. In addition to unfavorable chemical characteristics, child poisonings have been particularly troublesome. Most recently cannabis products are in the spotlight, but other over the counter and prescription poisonings have been and remain real problems. 

Do I have to use a credit card to order Maximum D3®?

No, you can pay by check. 

  • To place a check order online:
  • To place a check order by phone:

Checks should be mailed to:

Pro Pharma LLC
PO Box 220040
Kirkwood, MO 63122

Is Maximum D3® sold near me?

Maximum D3® is sold by many pharmacies, physicians and retailers.  Please contact your local business or physician to see if they carry Maximum D3®.  For online orders, please click here.

Is Maximum D3® gluten-free?

Yes, Maximum D3® is gluten-free.  There is NO gluten in the product.

Is Maximum D3® Kosher?

Maximum D3® is not Kosher.  Maximum D3® is not packaged in a Kosher facility. The gel caps before filling with soy lecithin and cholecalciferol are Kosher (Ko).  BSE free bovine (only) gel caps are manufactured in France or Japan by Capsugel to obtain a product which does not contain pork.

Does Maximum D3® contain GMOs?

No, Maximum D3® does not contain genetically-engineered ingredients (which are commonly referred to as GMOs or genetically modified ingredients).  Maximum D3® is non-GMO.

What is the correct dose of vitamin D?

The correct dose of vitamin D is generally thought to be about 1,200 to 1,400 IU/day and can be taken daily, weekly or perhaps monthly.  There is some data to suggest that very large doses (600,000 IU injections every 6 months) might not be good.  More is not always better, and too much can be harmful.

Maximum D3® 325 mcg (13,000 IU) was designed to meet the demonstrated needs in normal persons with the convenience of being taken just once per week.

The proper dose of vitamin D can vary based on your health condition, so it is always best to consult your physician about your specific health needs.

More detailed answer –

The dose of 1200-1400IU/day assumes a properly formulated and consistent product. There are problems:

Testing has consistently shown that a considerable portion of vitamin D sold in the United States is of poor quality. Potency, absorption and contamination are all issues. 

More confusing is that most of vitamin D’s role in the human body is not well understood.  The effect on calcium and bone are reasonably well understood. However, much more vitamin D is used at the local cellar level to regulate processes of our immune system. This is why vitamin D keeps coming up in relation to cancer and infections.

There is an ongoing disagreement in the academic literature about how to address this. The formal recommendations used for labeling are based on recommendations from a report by the Institute of Medicine in 2010 (1). This report only used data for overt bone disease. That decision cited a lack of adequate data to address other factors. (Best explained in the introduction by Dr. A. Catharine Ross, Chair.) The Endocrine Society and others have raised other questions and suggestions (2) and the issue remains an ongoing topic in the medical literature.

1 -

2 -

What should my Vitamin D blood level be?

Ideal blood levels vary by individual, but the target range is generally between 30 and 60ng/ml of 25(OH) cholecalciferol.  This answer is based on blood levels seen in persons with substantial sun exposure and limited clothing (lifeguards, agricultural workers, primitive groups).

  • It is generally recognized that the minimal blood level needed to prevent overt bone disease is 20 ng/ml.
  • There is decent evidence for suboptimal calcium absorption with levels below 32 ng/ml. 
  • Primitive sun-exposed populations have 25(OH)D levels predominantly in the 40-60 ng/ml range.

Maximum D3® was designed to meet the demonstrated needs in normal persons and still provide a substantial safety margin if other sources of vitamin D are consumed.

What are the contents of Maximum D3®?

The only ingredients in Maximum D3® are vitamin D3 (cholecalciferol), non-GMO soybean lecithin, FD&C Blue 1 on half of the gelatin shell, and bovine (beef) gelatin.

The pill is a small, size 2 hard gel capsule containing 325 mcg of quality cholecalciferol in a digestible oil base.  The capsules are manufactured, packaged and warehoused in FDA-registered and inspected facilities.  Quality, packaging and stability are to available USP and FDA standards.

Contains: Soy

How much Calcium do I need?

The Institute of Medicine generally recommends that adults consume 1,000 mg of calcium per day with a maximum limit of 2,000 mg.  However, recommended calcium intake can vary by age, gender and health condition.

General Calcium Principles

  • The Institute of Medicine and the National Osteoporosis Foundation both recommend dietary sources as the preferred method of calcium intake.  Calcium guidelines are for total dietary calcium, not supplement requirements.
  • The Institute of Medicine has recently raised concern about the ingestion of too much calcium carbonate in pill form (particularly among older women).
  • Calcium considerations are influenced greatly by several medical conditions - especially kidney disease - individual professional advice should be considered.
  • Current calcium supplements do not contain remotely adequate amounts of vitamin D for use as standalone vitamin D supplementation.
  • Calcium should not be taken with some medications.
  • Calcium carbonate requires acid for absorption and should be taken with food.
  • Calcium carbonate supplement contains 40% elemental calcium.
  • Calcium citrate does not require acid for absorption and contains 21% calcium.
  • Our bones are made of calcium phosphate and dairy products are an excellent source.
  • Convenience, cost and palatability are major considerations. (avoid bone meal products because of possible heavy metal contamination, "coral calcium" is calcium carbonate)

Vitamin D status appears to affect calcium absorption more than the amount of calcium taken:

Large doses of calcium supplementation may interfere with phosphorus adsorption:

Selected Food Sources of Calcium

D2 and D3 are different, and it is important to note the differences.

D2 is a plant hormone; animals make and use D3.  Both D2 and D3 are absorbed similarly, and both will activate the vitamin D receptor.  The difference is in the molecular arrangement of the side chains.  The D2 side chain provides a convenient attachment for an enzyme (not intended for vitamin D metabolism) that causes the D2 version to be broken down much more quickly and differently than D3.  Therefore, D2 is not as good for loading or maintaining vitamin D levels.

How these differences affect regulation of vitamin D activity at the cellular level is not well understood.  Note that Europe largely moved away from D2 about two decades ago.

Why is vitamin D a hormone and not a vitamin?

Technically, D3 is a pro-hormone and not a vitamin, but it can be taken as if it were a vitamin. Humans can make vitamin D3 but require sunlight on exposed skin to do so.  Housing, clothing and indoor jobs were not in the original design specifications.  D3 is an intermediary prohormone made by the sunlight step.  Importantly, hormone production and activity require regulation to work correctly.  Hence, we need enough, but not too much, D3 to replace the lack of sun exposure.

Should I take supplemental vitamin K2?

UPDATE September 2019 -

To date, credible follow-up studies have failed to confirm the initially reported benefits of K2 supplementation in circumstances other than identified vitamin K deficiency. The NIH and FDA continue to group the K vitamins as a single group and the FDA has not authorized a health claim for vitamin K in the United States.

While too soon to form a conclusion, a very recent study has been released by a highly respected journal on nutrition. This registered study suggests that MK-7 supplementation may accelerate calcium deposition in atherosclerotic cardio/vascular disease. This would be an important issue for a substance that lacks clearly demonstrated benefit for the general population. There is not cause for panic, but reassessment may be warranted.

“MK-7 supplementation tended to increase active calcification measured with 18F-NaF PET activity compared with placebo, but no effect was found on conventional CT. Additional research investigating the interpretation of 18F-NaF PET activity is necessary. This trial was registered at as NCT02839044.” The article and discussion are available at:


February 2018 -

As of now, the honest answer is that there is not enough consistent or quality data to definitively answer this question.  Potential problems have been identified that are unanswered.

Vitamin K refers to a group of chemical compounds that vary in their side chains. K vitamins do many things. K2 is mistakenly described as a cofactor for vitamin D. It is not. K2 does play a role in the maintenance of bone.

Deficiencies in K2 are uncommon and occur mostly in recognized situations. Human needs are not well established, but known to be tiny.  Need for supplementation in the general population has never been demonstrated. (Humans derive much of their K2 group from bacteria in their own intestinal tract.)

Bone – Extensive reviews of the studies on supplementation with K2 even in the setting of osteoporosis continue to lack consistent and convincing data.

“routine VK supplementation is not globally recommended yet in postmenopausal women affected by osteoporosis, as low-quality cross-sectional and RCTs have provided contrasting evidence. In fact, most of the studies that have analyzed the interaction between bone health and VK are characterized by several limitations and the findings should be therefore addressed with caution.”

Vitamin K and osteoporosis: Myth or reality? Review Article

Metabolism Volume 70, Pages 57 – 71 (May 2017)

Andrea Palermo, Dario Tuccinardi, Luca D'Onofrio, Mikiko Watanabe, Daria Maggi, Anna Rita Maurizi, Valentina Greto, Raffaella Buzzetti, Nicola Napoli, Paolo Pozzilli, Silvia Manfrini

Vascular disease – There is a great deal of interest in “K2 vitamins” for the prevention of vascular disease. The suggestion comes from observational epidemiology data and is far from conclusive.

“However, further studies using screening tools to find the mostly asymptomatic PAD population are warranted before our findings can be generalized.”

The relationship between vitamin K and peripheral arterial disease

Linda E.T. Vissers , Geertje W. Dalmeijer , Jolanda M.A. Boer , W.M.Monique Verschuren , Yvonne T. van der Schouw , Joline W.J. Beulens

Atherosclerosis 252 (2016) 15e20

Multiple roles - Potentially either good or more troublesome are that K2 does many things in several human tissue types. These functions are incompletely understood. Some “K” compounds have been shown to affect intracellular signaling pertinent to some types cancer cells. Suppression of K vitamins (warfarin data) are associated with a reduction in the incidence of some cancers. Whether high doses – as in some supplements promoted – are harmful is not known.

Several K2 questions remain “moving targets.”