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Study: Significant variability exists in dissolution of popular nutritional supplement
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Five multivitamin supplements dissolved within 60 minutes in an environment simulated to resemble the human stomach, while three ocular multivitamins remained undissolved at 18 hours, a study found.
“There is wide variability in commonly available multivitamin supplements with respect to dissolution, potentially impacting the absorption of nutrients,” study author Kimberly Reed, OD, FAAO, said in a poster presentation at the American Optometric Association’s annual meeting.
The pilot study tested 10 well known multivitamins, three of which have been commonly recommended for ocular health. Pills were submerged in two liquids, the first with a pH of 4.0 to simulate the acidity of a stomach with food/drink and the second with a pH of 2.0 to simulate the acidity of an empty stomach.
Pills were left undisturbed for 60 minutes in both acidic solutions.
Results
According to the study, supplement “D” was the first to begin dissolving under both pH conditions after approximately 20 minutes in the 4.0 pH solution and 22 minutes in the 2.0 pH solution. Supplements F, H and E started to dissolve before 40 minutes in the 4.0 pH solution and before 55 minutes in the 2.0 pH solution. Supplements A, B and C were still undissolved in both acidic solutions after 18 hours and remained undissolved after being bathed in tap water and resubmerged in an alkaline environment of 8.0 pH for 3 days.
Dr. Reed suspects that the gelatin coating on supplement D helped it dissolve more quickly than the others.
“Not every supplement is going to behave the same; there’s a lot of variability because supplements are not regulated the same way that drugs are regulated,” Dr. Reed told Primary Care Optometry News.
Importance of dissolution
Though many supplements and medications are deliberately designed for delayed release or extended release application, Dr. Reed continued, none of the supplements tested were labeled as extended release. However, pharmaceutical companies are not required to differentiate the length of dissolution, making it difficult to determine whether the multivitamin is a failure or whether it was specifically formulated for delayed release.
It is imperative to recommend a supplement that will dissolve in a timely manner so the nutrients it contains are able to enter the bloodstream and benefit the patient, Dr. Reed told PCON.
“Nutrients from food and supplements are absorbed in the small intestine, directly into the bloodstream,” she said. “Large particles of food or vitamins that cannot pass through the tiny openings into the bloodstream pass through [the body] without being absorbed.”
Dr. Reed suggested that practitioners try a simple at-home test: drop samples of commonly recommended supplements into a glass of water and time them to determine dissolution rates. Doctors can then be sure to recommend the best vitamin to suit the patient’s need, she said.
“Before making blanket recommendations to patients, doctors need to know what formulation they’re recommending so they can be confident it has a chance of being absorbed,” Dr. Reed said.
She is planning a follow-up study using the U.S. Pharmacopeia disintegration technique of plain water and swirling to retest the same multivitamins. — by Stephanie Vasta
Reference:
- Reed K, Berman SR. Dissolution rates of multivitamin supplements. Poster presented at: American Optometric Association annual meeting; June 17, 2010; Orlando, Fla.
- Kimberly Reed, OD, FAAO, can be reached at NOVA Southeastern University College of Optometry, 3200 South University Drive, Ft. Lauderdale, Florida 33328; 954-262-4227; kimreed@nova.edu.
