The body is an amazing machine with many biochemical reactions resulting in health and for some, disease.

Many of us have learned about the importance of the fat soluble vitamin A (retinol) and its partner, beta-carotene and its contribution to health and well-being.

Vitamin A (retinol) has specific maintenance roles that include vision, bone growth, skin, and mucosal integrity. Inadequate vitamin A levels are associated with increased respiratory infections, skin conditions, and infertility.

Carotenoids are the plant sources of vitamin A.

The most well studied carotenoid is beta-carotene. The absorption of beta-carotene and its conversion to vitamin A varies among individuals. Beta-carotene is converted into vitamin A in the liver. Of all the carotenoids, beta-carotene is converted into retinol most efficiently.

With this level of importance we may assume simply taking vitamin A supplements or eating foods high in vitamin like carrots, sweet potatoes and pumpkin would satisfy the daily vitamin A requirement.

Unfortunately, I want to share an important biochemical action that may negate any of the benefit derived from striving to increase your vitamin A levels.

As we now know, the important carotenoid, beta-carotene, is converted to retinol. Meaning this biochemical conversion must happen in order for us to gain all of the great benefit of vitamin A.

But it comes with a requirement.

And that requirement is zinc.

Without optimal levels of zinc the conversion of beta-carotene to retinol (vitamin A) just won’t happen.

The following lab test shows high levels of beta-carotene and low levels of vitamin A.

Zinc may the root cause of this conversion problem

With this new knowledge I bet you know why?

In most cases, a deficiency of zinc may be the culprit.

Now if you find that beta-carotene appears not to be converting to retinol do you automatically assume that zinc is the root cause of this conversion issue?


It is best to put your detective hat on and do some investigating.

One direct objective test is to order an erythrocyte and whole blood nutrient test and take a look at the zinc levels. The following test is one of your best markers for measuring zinc levels.

Another indirect measurement is to take a look at the alkaline phosphatase test on your basic or comprehensive metabolic blood panel. Alkaline phosphatase is a zinc dependent enzymeDecreased levels less than 70 have been associated with zinc deficiency.

Also look for white spots on the fingernail beds, reduced sense of smell or taste. These may both be signs of a zinc deficiency.

You may be thinking what causes zinc deficiences?

One of many reasons for low zinc levels include numerous medications, environmental toxins and processed foods.

In addition industrial and auto exhausts produce acid rain that depletes zinc from the soils and foods, etc.

This is a great example of the power of functional medicine. Basically we are looking for the cause of the cause of the cause.

With this powerful form of medical detective work can you imagine the multitudes of patients who can be helped.


By Ronald Grisanti D.C., D.A.B.C.O., D.A.C.B.N., M.S.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Grisanti and his community. Dr. Grisanti encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. Visit to find practitioners thoroughly trained in functional medicine. Look for practitioners who have successfully completed the Functional Medicine University’s Certification Program (CFMP).

This content may be copied in full, with copyright, contact, creation and information intact, without specific permission, when used only in a not-for-profit format. If any other use is desired, permission in writing from Dr. Grisanti is required.

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