Spray vitamins:
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 grabbed 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, and this is why I "jumped on the topic" and decided to dedicate a separate page to spray vitamins.

(By that time I wrote already about
solid supplements, liquid vitamins and
gel supplements.)

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 was I looking for to know about spray vitamins.
Well, let's start from the beginning...

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.
Two statements are the most common.

1. Superior vitamin absorption rate is achieved by the spray as a method of vitamin delivery
2. Frequent oral sprays give a more constant level of vitamins in the body

I decided to have a closer look onto these claims,
and here is what I discovered.

This is a cornerstone of the spray vitamins industry. Per manufacturers, vitamins and minerals, when sprayed into a mouth, bypass the digestion system, and got absorbed directly into a bloodstream through mouth tissues. This is what they call "oral absorption".

As a proof for this claim, a report from Physician's Desk Reference (page 1542 of the 1996) 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, and articles are provided by manufacturers of new products!
Using the report from 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...

It turns out, "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) absorption in the gastrointestinal when taken orally. Many information sources imply exactly this meaning of the term "oral absorption".

The best quote about what "oral absorption" means, is the following:

Different parts of oral tissue have different permeability (an ability to transmit a fluid). The higher permeability of a tissue, the better this tissue can absorb liquids. Sublingual mucosa is the thinnest among mouth tissues, and has the highest permeability. Drugs taken sublingually are absorbed better than drugs that are held under 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 drug is swallowed, it can take hours before the desired concentration in blood is reached. In case of sublingual path it can take just minutes.

• It allows a drug to bypass a digestive system.
  Some substances, when swallowed, can be destroyed before they reach the bloodstream. This can happen in stomach, small intestine, or in liver. Sublingual path takes a drug directly into the bloodstream. Another case when sublingual method can help, is when a person cannot digest some specific nutrient due to a medical condition (like in 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 shots. Because some substances can be absorbed without swallowing, sublingual method can help here.
  Wouldn't you agree that taking a medicine, or a dietary supplement, under the tongue is better that taking a shot? There are also other methods of drug delivery (rectal, vaginal, nasal) which are less convenient than a sublingual method.

How well a drug would be absorbed by oral tissues depends on its physical and chemical characteristics.

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 that 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 would penetrate cell membranes more easily.

• Small molecules penetrate through oral tissue better than larger molecules.

• Molecules penetrate better than ions (ion is a charged molecule, or atom).

Having this information, what can we say about sublingual absorption of spray vitamins?

• Based on solubility factor, it seems that water-soluble vitamins (vitamins C, H, B complex) would be absorbed not as good 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 biggest molecular weight of 1357.
  This means that vitamins might be absorbed sublingually - but not as good as substances with smaller molecules (for example, alcohol, with molecular weight of 46).

• There are vitamins with neutral molecules, like vitamins B3, B12. Others have positively charged molecules, like vitamin B1 (thiamine), and some vitamin molecules carry negative potential, like vitamin C (ascorbic acid), or B2 phosphate.
  As neutral molecules can be absorbed better that charged molecules (ions), it seems like some vitamins would be absorbed in the mouth better than others.

Now it 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 go and cite some research papers which explored the topic of sublingual vitamin absorption, and concluded that this is the most effective delivery method?

The answer is simple: there are no such research papers.

I'm sorry, more accurately: I could not locate any research paper which would approve - or disapprove - claims made by spray vitamins manufacturers.
Not a single research.
Not about "better absorption", not 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 a 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 of spray vitamins, or not, after all?..

Based on what I learned, I think there are benefits of spray vitamins.

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 are going directly to the bloodstream, bypassing gastrointenstinal and liver. This can benefit some people who have digestive problems, especially at the 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. In addition...

• Sprays are more convenient than liquid vitamins. They are portable, do not require refrigerating after opening, and provide more precise dosage with metered sprays. These "usability" features of spray vitamins can also be found in gel supplements.

References:

1. "The Permeability of Oral Mucose", C. A. Squier, Critical Reviews in Oral Biology and Medicine, 2(1): 13—32 (1991)
2. "Absorption Through Oral Mucous Membranes", E. R. Lalonde, Journal of Dental Research 48(5): 680-684, 1969
3. "Passage of drugs across body membranes", Shanker L. S., Pharmacological reviews, 1962; 14: 501-530
4. "Effect of pH on Sublingual Absorption of Oxycodone Hydrochloride", A. M. Al-Ghananeem et al, AAPS PharmSciTech 2006; 7 (1) Article 23 (link)
5. "Current status in buccal drug delivery", L. I. Giannola et al, Pharmaceutical Technology Europe, May 2008 (Chem. Educator 2002, 7, 23–26 (link)
6. "Absorption of vitamin C from the human buccal cavity", F. Sadoogh-Abasian, D. F. Evered, Br. J. Nutr. (1979), 42, 15
7. "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