Vitamin A: Rethinking Retinol

Posted on November 30, 2015 by Dr. G

1. Weight loss.
2. Fatigue.
3. Thyroid hormone health.
4. Autoimmunity.
5. Leaky gut syndrome.
6. Depression and mood disorders.

It is very important to understand the role of vitamin A in your life. Early symptoms of vitamin A deficiency could be any one of the above, but the official symptom for early detection of vitamin A deficiency is difficulty with night vision or night blindness. Waiting for night vision difficulties is, in my opinion, waiting too long. In this country, subclinical deficiencies can be expected in people with chronic health issues related to the immune system, infection, digestion, liver function, or metabolic syndrome.

Inflammation is a major component of every major chronic health condition known to the modern industrialized world. Chronic inflammation is is a product of the immune system and occurs when there is dysregulation of the immune system.

There are many components of a healthy, functioning immune system. This post will focus on a nutrient usually associated with vision: vitamin A. Vitamin A is important for vision and fetal organ development. It is also a key component for:

• Thyroid hormone function
• Red blood cell health (hemoglobin concentrations)
• Fat burning / insulin resistance
• Immune function
• Gene transcription

Vitamin A and Vitamin D have shared characteristics:

We have discussed the role vitamin D plays in regulating the immune system and how subtle deficiencies can play out in immune system-based diseases like autoimmunity, lyme disease and even cancer.

We have also discussed how our understanding of vitamin D began with its relationship to bone development and the prevention of a third-world nutritional deficiency bone disease called “rickets.” That is where the recommendations for intake of vitamin D come from. Our healthcare system’s failure to acknowledge the importance of vitamin D and its relationship to the immune system results in our recommended levels of vitamin D intake and levels of vitamin D 25 hydroxy in our blood to be dangerously low.

Some patients, particularly in those with immune system challenges, benefit so greatly from elevating vitamin D to the upper end of the normal limits (80-100 ng/dl) that it often makes me look like I am a smarter and better doctor than I am. I believe understanding vitamin A holds a similar promise as vitamin D to those who are susceptible to subclinical deficiency.

Vitamin A is an immune regulator:

The following quote from the International Medical Council on Vaccination shows just how important Vitamin A is for immune regulation–specifically, in this case, as it relates to the measles virus:

“Vitamin A stops the measles virus from rapidly multiplying inside cells by up-regulating the innate immune system in uninfected cells which helps to prevent the virus from infecting new cells. It is well known today that a low vitamin A level correlates with increased morbidity and mortality. Vitamin A is a well-proven intervention for reduction of mortality, concomitant infections, and hospital stay.

When the body fights any infection, but especially measles, vitamin A stores become depleted by various mechanisms. Measles infections and high-titer measles vaccines both impair cell-mediated immunity, in part because of vitamin A depletion.”

It is believed by many medical researchers that adverse reactions to the measles virus is, by definition, a vitamin A deficiency disease.

Vitamin A was initially coined “the anti-infective vitamin” because of its importance to the normal functioning of the immune system. Like vitamin D, vitamin A is tied to the 24 hour light cycle and how we manage hormones, neurotransmitter and blood chemistry based on circadian biology. The importance of paying attention to how we interact with natural and artificial light cannot be underestimated.

Vitamin A is fat soluble:

Vitamin A deficiency is the number one cause of preventable blindness around the world. A major concern around the world, but like rickets, not so much in the US. When the obvious vitamin deficiency disease is avoided, it is too often thought that deficiency is no longer a concern. Vitamin D and vitamin C should have been a lesson to us (the eradicated vitamin C deficiency disease is called scurvy, about 60 mg/day is required to prevent scurvy, but Linus Pauling showed that we could benefit by taking 2-5 grams per day and in some cases up to 15 grams per day). High dose forms of vitamin A are used medicinally as treatment for diseases like acute myelocytic leukemia and various skin disorders. Vitamin A is one of the few fat soluble vitamins along with Vitamins D, E and K. That means that excessive intake can result in toxicity.

Vitamin A, autoimmunity and leaky gut:

Immune cells that line the mucosa in our airway (including the lungs), digestive tract, urinary tract and skin are called dendritic cells (DCs) and antigen presenting cells (APCs). The DCs and APCs are our first line of defense and their job is to communicate to the rest of the immune system whether a foreign protein they encounter is harmful or not. This is a very important function because if these protective cells sound the alarm bells to the rest of the immune system when they encounter something that should be harmless, like dairy, egg or wheat protein, then every time you eat those foods you can mount an all-out inflammatory response as if you’ve just been invaded by a harmful virus or bacteria. When the immune system is mobilized by what should be tolerable harmless food proteins, it’s called leaky gut. Leaky gut is the first step toward autoimmunity. One of the most common types of autoimmunity is called Hashimoto’s which results in hypothyroid disease. There are many autoimmune diseases that could also be explained by this mechanism.

A form of vitamin A called retinoic acid is what determines if the DC’s and APC’s of the immune system overreact to the presence of what should be harmless, tolerable foreign proteins from food, healthy bacteria, pollens, etc. The role vitamin A plays is called T cell regulation.

Single dose vitamin A supplementation increased neutrophil and natural killer cell activity of white blood cells.

Vitamin A and Anemia:

Anemia refers to a defect in one or more characteristics of red blood cells. Red blood cells are important because they deliver oxygen to the cells that need them, and all cells need oxygen, with the most oxygen-sensitive cells in the body being brain cells. Decreased oxygen availability due to anemia will begin with symptoms of brain fog and fatigue. Severe anemia can result in serious illness and death. There are several types of anemias. Vitamin A is involved with the ability to metabolize dietary iron into the red blood cells. Iron is what carries the oxygen molecule. Vitamin A is also involved in the presence of the protein hemoglobin in our red blood cells. Hemoglobin is what carries the iron, which carries the oxygen.

Studies have shown a reduction of anemia resulting from just one megadose of vitamin A and no iron supplementations, in addition to simultaneous benefits to white blood cell function.

Vitamin A in depression and mood disorders:

Vitamin A in the form of retinoic acid is part of a superfamily of nuclear receptors that control gene transcription and neurogenesis (formation of new brain cells). Vitamin A has been shown to impact behavior. The neurotransmitter model of pharmacology has not lived up to its promise and new avenues are being explored as they relate to gene expression. This is the case with Vitamin A.

Sources of Vitamin A in our diet:  Animal or Vegetable.

Vitamin A is found in food as either a form of vitamin A itself or as a precursor to vitamin A. Animal products, like fish, beef liver, cod-liver oil and eggs contain the preformed vitamin A we use. Vegetables contain precursors to vitamin A called carotenoids. Some examples include foods like sweet potato, pumpkin, carrot, cantaloupe, spinach, broccoli, kale, squash and many more colorful vegetables.

The problem with the vegetable source precursors of vitamin A is that our ability to convert the carotenoids to the usable forms of vitamin A varies greatly from individual to individual and from food source to food source: “There is a wide variation in conversion factors reported not only between different studies but also between individuals in a particular study.”  Animal sources of vitamin A are preferable.  

In Western societies, the provitamin A carotenoids derived from plants provide less than 30% of daily vitamin A intake, whereas preformed vitamin A derived from animal products provides more than 70% daily vitamin A intake. Vice/versa is true in developing nations.

According to research, the bioconversion of beta carotene to vitamin A in the body is not as efficient as expected and, as a result, there has been a revision of the estimated efficiency factor for the conversion of dietary beta-carotene to vitamin A from 6:1 by weight to the new value of 12:1 by weight. However, this new conversion ratio must be regarded as temporary and could (and likely will) change. On the other hand, preformed vitamin A from animal origins or from supplements can be absorbed and stored in the human body very effectively.

One factor that predicts the ability to convert dietary vegetable source beta-carotene and carotenoids to the usable retinol is BMI. Increased body fat means decreased conversion ability.

Supplementing Vitamin A.

Vitamin A in the usable animal form retinol, retinoic acid (RA) or retinyl palmitate is fat soluble and if not taken properly can cause issues of toxicity, whereas beta-carotene precursors to vitamin A are not fat soluble and therefore can be taken in high doses without risk of vitamin A toxicity. There is risk, however, that the beta-carotene (an antioxidant) can be severely oxidized, resulting in unwanted free radicals in our system.

Supplementation should be supervised by a clinician to avoid toxicity. When managed properly, vitamin A can provide patients suffering from chronic illness with a much needed ability to heal and restore health. If you are already healthy, all vitamin A needs are present in a healthy diet as is outlined on this website.

Factors affecting bioavailability conversion of dietary and supplemental vitamin A and vitamin A precursors.

Processing vitamin A in our diet requires:

1. Healthy fat intake. Vitamin A is fat soluble.
2. Proper stomach acid producing abilities (Antacids like proton pump inhibitors used to treat acid reflux will inhibit vitamin A absorption).
3. Small intestinal mucosal health.
4. Healthy liver and gallbladder function (Fat absorption and liver storage and conversion pathways are often compromised when there are chronic health issues).

These four factors mentioned above are present in 80% of my patients and, in my opinion, 80+% of people suffering from chronic diseases or chronic symptoms.

We have touched on a lot of important points as they relate to Vitamin A and many of the associated health issues. If you have specific questions, there is a good chance others will have the same questions. Please use the comments section to post your question and I will do my best to answer each of them.

Thanks for reading!