DEAR DR. BLONZ: My question is not about taking supplements, but whether there is a difference in nutritional value between those taken as pills and those taken in liquid or other forms. A close friend tells me that the multivitamin pills I take are essentially useless, as most of their nutritional value never gets absorbed as they pass through the digestive system. She is convinced that liquid vitamins are the way to go, as the body almost totally utilizes them. She mentioned that liquid supplements are 97 percent bioavailable and absorbable, while pills, capsules and tablets are 3 to 20 percent absorbed. Please comment. -- A.H., Scottsdale, Arizona
DEAR A.H.: We first must assume that amounts stated on the Supplement Facts label are in the product (likewise, that everything in that product is declared on the label). Assuming we are dealing with similar compounds and amounts, the key would be whether they are in solution by the time they reach the small intestine area, where they would be absorbed. That being the case, it would make no difference whether the product was in a pill, tablet, capsule, gelcap, powder, or a liquid form before you swallowed.
The USP, which stands for the United States Pharmacopeia, sets standards for ingredients’ strength, quality and purity. Their standards are that plain-coated tablets should disintegrate within 30 minutes in a simulated gastric environment. Delayed-release products should dissolve after having held together for an hour. That “delay” can be used with compounds at risk of being destroyed in the stomach’s acidic environment. Coatings that delay release are also used with compounds formulated for slow release rather than all-at-once release. These techniques are also used with medications.
Assuming your digestive system is functioning normally, and there is no medical reason to take a particular form, products meeting USP standards should provide enough time for the contents to be available for absorption when they arrive at the region of the intestines where it should happen. Having supplements along with a meal helps, as digestion and absorption systems are already on their game.
The figures your friend cited regarding the variance in bioavailability and absorption between pills and liquids are misleading. Pills, tabs or gelcaps can have an element of convenience, so the idea that they are primarily useless sounds like a sales pitch from a company selling liquid supplements. No doubt nutrient absorption can vary, but this will depend more on your age, health, gender and whether the product is taken with a meal.
The FDA has a set of good manufacturing practices for supplement companies, and there are also regulations that dietary supplements should meet the USP standards for disintegration and dissolution. Check whether your brand meets the USP standards; this information should be available from the manufacturer -- and should be considered a red flag if not. For those wanting to “absorb” the details, check the USP chapter on the disintegration and dissolution of dietary supplements at b.link/ht6h6s. Another site to consider is ConsumerLab.com, as they subject all the products they evaluate to a dissolution test; products do not get “approved” if they fail this aspect of the evaluation.
Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.