What's beyond the buzz?
I saw the term "spray vitamins" for the first time when I was looking for information about vitamin absorption and bioavailability.
It caught my attention immediately, because spray is yet another delivery form of dietary supplements. Different delivery methods of dietary supplements is the main subject of this website, which is why I "jumped on the topic" and decided to dedicate a separate page to spray vitamins.
(By this time, I had already written about
solid supplements, liquid vitamins and
My searches took me through scientific papers and FDA alerts, to obscure websites, to blogs about psychotropic drugs...
This was not an easy task.
You may wonder what I was looking for about spray vitamins.
Well, let's start from the beginning.
Claims about spray vitamins
Each delivery form of dietary supplements has its strong and weak points, and each supplement of a new delivery form must have some advantage over existing supplements.
Obviously, manufacturers of a new supplement will emphasize such advantage, to show how unique the new product is.
There are many claims made by companies which manufacture and sell spray vitamins.
These two statements are the most common:
- Superior vitamin absorption rate is achieved by the spray as a method of vitamin delivery
- Frequent oral sprays give a more constant level of vitamins in the body
I decided to have a closer look at these claims,
and here is what I discovered.
Better absorption of spray vitamins
This is a cornerstone of the spray vitamins industry. According to manufacturers, when vitamins and minerals are sprayed into the mouth, they are absorbed directly into the bloodstream through mouth tissues and bypass the digestion system. This is what they call "oral absorption".
As a proof for this claim, a report from the Physician's Desk Reference (page 1542 of the 1996 issue) is often cited. On many websites you can see statements that this report provides a proof that spray vitamins have better absorption than other forms of dietary supplements (liquid vitamins, pills, etc.).
In reality, this report is not an independent, scientific, peer-reviewed paper. The purpose of this report is to inform medical professionals about new drugs and supplements. The articles are actually written by the manufacturers of these new products!
Using the report from the Physician's Desk Reference as a proof for claims about better absorption of spray vitamins would be like saying:
This is correct, because I wrote in the past that this is correct!
Once I realized that the main claim might not be 100% true, I turned to the subject of the claim: oral absorption.
The first thing I found out was that this term is also not used correctly.
What is oral absorption?
It turns out that oral absorption does not mean that a substance is absorbed inside the mouth.
The term oral absorption describes the process of a supplement (or drug) being absorbed in the gastrointestinal tract when taken orally. Many information sources imply exactly this as the correct definition.
The best quote about what oral absorption means, is the following:
"Drug bioavailability is the outcome of a complex chain of events, and is among others influenced by the drug's solubility, permeability through the gastrointestinal wall, and its first pass gut wall and liver metabolism.(Excerpted from the book "Drug Bioavailability",
Excluding liver metabolism, all other factors are characterized by the term oral absorption."
edited by Hans Han van de Waterbeemd et al.
Here is this book on Amazon.com.)
To describe the process of absorption inside the mouth, the correct term would be either "sublingual absorption" (delivery of a substance through the mucosal membranes lining the floor of the mouth), or "buccal absorption" (when substance is absorbed through the mucosal membranes lining the cheeks) - and not just "oral absorption".
Different parts of oral tissue have different degrees of permeability (the ability to transmit fluid). The higher permeability capacity of a tissue, the better this tissue can absorb liquids. Sublingual mucosa is the thinnest among mouth tissues, and has the highest permeability capacity. Drugs taken sublingually are absorbed better than drugs that are held inside the cheek.
Compared to other ways of a drug/supplement intake, sublingual absorption has the following benefits:
- It is much quicker than other methods.
Drug impact is measured by its concentration in blood. When a drug is swallowed, it can take hours before the desired concentration in blood is reached. In case of the sublingual path it can take just minutes.
- It allows the drug to bypass a digestive system.
Some substances, when swallowed, can be destroyed before they reach the bloodstream. This can happen in the stomach, small intestine, or in the liver. The sublingual path takes a drug directly into the bloodstream. Another case when the sublingual method can help is when a person cannot digest some specific nutrient because of a medical condition (as in the case of sublingual B12).
- It is more acceptable than other delivery methods.
In cases when a drug cannot be swallowed, a usual way is to prescribe injections. Since some substances can be absorbed without swallowing, the sublingual method can be of help here.
Wouldn't you agree that taking a medicine or a dietary supplement under the tongue is better than taking an injection? There are also other methods of drug delivery (rectal, vaginal, nasal) which are less convenient than a sublingual method.
Factors impacting sublingual absorption
The physical and chemical characteristics of a drug will determine how well it can be absorbed.
There are several factors which determine how substances (drug, vitamins or minerals) are absorbed inside the mouth:
- Fat-soluble drugs are absorbed better when taken sublingually than are water-soluble ones.
Tissues inside the mouth, as any body tissue, consist of cells, and the cell membrane is lipoidal (fat-like). Because of this molecules of materials which are better soluble in fat can penetrate cell membranes more easily.
- Small molecules penetrate through oral tissue better than larger molecules.
- Molecules penetrate better than ions. (An ion is a charged molecule, or atom.)
Having this information, what can we say about sublingual absorption of spray vitamins?
- Based on the solubility factor, it seems that water-soluble vitamins (vitamins C, H, B complex) would not be absorbed as well as fat-soluble vitamins (vitamins A, D, E, K).
- Recent studies show that small molecules (molecular weight less than 100) cross the oral mucosa easily.
Molecular weights of all vitamins are greater than 100. Vitamin C has the smallest weight of 176, and vitamin B12 has the highest molecular weight of 1357.
This means that vitamins might be absorbed sublingually - but not as well as substances with smaller molecules (for example, alcohol, with molecular weight of 46).
- There are vitamins with neutral molecules, such as vitamins B3 and B12. Others have positively charged molecules - vitamin B1 (thiamine), and some vitamin molecules carry negative potential - vitamin C (ascorbic acid) or B2 phosphate.
As neutral molecules can be absorbed better than charged molecules (ions), it seems that some vitamins would be absorbed more easily in the mouth than would others.
Do spray vitamins work?
Now is a good time for you to ask:
Why do you need all this guess work to figure out whether spray vitamins work? Why don't you just cite some research papers which have explored the topic of sublingual vitamin absorption and have concluded that this is the most effective delivery method?
The answer is simple: there are no such research papers.
I'm sorry, more accurately said: I could not locate any research paper which would approve - or disapprove - claims made by spray vitamins manufacturers.
Not one single piece of research.
Not about better absorption, nor about constant level of vitamins in the body.
(I spent quite a lot of time searching. The list of sources which I found and used while creating this webpage is given below.)
There are papers about sublingual absorption of some vitamins, for example, vitamins C and B12. None of them reports that a sublingual route is superior.
One paper about vitamin B12 confirms that a sublingual method is just as effective as the regular oral route. As concluded in that paper: "A dose of 500 micro g of cobalamin given either sublingually or orally is effective in correcting cobalamin deficiency." (Here is the link to the abstract of the paper.)
So, are there any benefits to spray vitamins, or there are none, after all?..
Benefits of spray vitamins
Based on what I learned, I think there are.
Here is "my" list; it is different from those provided by manufacturers :-)...
- There is no better absorption of vitamins when taken sublingually - but they are absorbed!
When absorbed sublingually, nutrients go directly into the bloodstream, bypassing gastrointenstinal tract and the liver. This can benefit some people who have digestive problems, especially at an older age.
- Even if not absorbed in the mouth, spray vitamins can be swallowed - just like liquid vitamins. In this case, all advantages of liquid vitamins would apply to spray vitamins as well.
- Sprays are more convenient than liquid vitamins. They are portable, do not require refrigeration after being opened, and provide more precise dosage with metered sprays. These "usability" features of spray vitamins can also be found in gel supplements.
- "The Permeability of Oral Mucose", C. A. Squier, Critical Reviews in Oral Biology and Medicine, 2(1): 13—32 (1991)
- "Absorption Through Oral Mucous Membranes", E. R. Lalonde, Journal of Dental Research 48(5): 680-684, 1969
- "Passage of drugs across body membranes", Shanker L. S., Pharmacological reviews, 1962; 14: 501-530
- "Effect of pH on Sublingual Absorption of Oxycodone Hydrochloride", A. M. Al-Ghananeem et al, AAPS PharmSciTech 2006; 7 (1) Article 23 (link)
- "Current status in buccal drug delivery", L. I. Giannola et al, Pharmaceutical Technology Europe, May 2008 (web page)
- "Capillary Electrophoresis of Water-Soluble Vitamins: An Undergraduate Experiment", V. Salvado, J. M. Sanches, >Chem. Educator 2002, 7, 23–26 (link)
- "Absorption of vitamin C from the human buccal cavity", F. Sadoogh-Abasian, D. F. Evered, Br. J. Nutr. (1979), 42, 15
- "Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route.", Sharabi et al, Br J Clin Pharmacol. 2003 Dec;56(6):635-8
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