Vitamin A: Benefits, Deficiency and Food
- by Dr. Daniel
- Published on
What is Vitamin A?
Vitamin A is a fat-soluble vitamin that plays major roles in maintaining vision, neurological function, healthy skin and immunity.
There are two forms that Vitamin A can exist in: Plant forms and Animal Forms.
The plant form consists of a collection of compounds known as “carotenoids” and the animal form is known as retinol.
Humans do not require the plant form (carotenoids), but do need the animal form (retinol).
What's important here is that humans can convert carotenoids into retinol; as long as the body is functioning optimally.
Speaking of carotenoids. There are over 600 different carotenoids and not all of them act like Vitamin A.
For example, Lutein and Zeaxanthin, both help to protect us from blindness as we age, but they don't act like vitamin A in the body.
Lycopene is another carotenoid that may protect us against prostate cancer and heart disease, but again, it doesn't act like vitamin A in the body.
Only 10% of carotenoids act as vitamin A, and these carotenoids are called “provitamin A carotenoids”.
The ‘pro' just means that the body can convert them into retinol (the active form of Vitamin A).
Vitamin A Benefits
Top 10 Benefits of Vitamin A include:
- Eye Health
- Supports Immunity
- Decreases Inflammation
- Healthy Skin
- Cancer Protection
- Bone Health
- Cholesterol Reduction
- Reproduction and Development
- Tissue Health & Repair
- Kidney Stone Prevention
1. Eye Health
Vitamin A helps to boost vision, keep your eyes moist, signals the brain that its daylight and even helps to improve night time vision.
2. Supports Immunity
Another interesting function of vitamin A is that it supports the tiny hairs lined up within your throat and lungs which catch all the junk and little microbes that you breath in and out.
One study found that vitamin A deficiencies were associated with weakened immune function. [1]
Another study found that by simply giving vitamin A supplements to children, over $340 million in medical costs could be reduced due to medical conditions. [2]
In addition, A Cochrane review of eight randomized controlled trials of treatment with vitamin A for children with measles found that 200,000 IU of vitamin A on each of two consecutive days reduced mortality from measles in children younger than 2 and mortality due to pneumonia in children. [3]
3. Decreases Inflammation
One of the biggest benefits of vitamin A is it's ability to act as an antioxidant in the body, helping to reduce oxidative stress and inflammation. [4]
And because inflammation is at the heart of all chronic disease, maintaining adequate levels of vitamin A could help prevent cancer, heart disease, diabetes and neurodegenerative diseases.
4. Healthy Skin
Vitamin A is often prescribed by dermatologists to fight acne, wrinkles and various skin conditions. Several studies show that retinoids may be therapeutic for skin conditions such as psoriasis, eczema and acne. [7, 8, 9].
5. Cancer Protection
A growing body of research is now demonstrating the strong links between the food you eat and your risk of developing cancer. [10]
According to a review published in BioMed Research International, retinoids have been shown to block the growth of skin, bladder, breast, prostate and lung cancer cells in in vitro studies. [11]
But before you go and swallow a ton of vitamin A, appreciate the fact that the best way to get vitamin A is from food sources.
6. Bone Health
We all know that bone health requires nutrients like calcium, magnesium, vitamin D and vitamin K.
But did you know that vitamin A plays a critical role in bone health?
Hitting just the right balance of vitamin A is essential, however, as both an excess and deficiency in this important vitamin have been linked to compromised bone health. [12]
One study conducted at the Institute of Gerontology and Geriatrics at the University of Perugia in Italy even found that plasma retinol levels were significantly lower in elderly women with osteoporosis compared to a control group.
The results also showed that low levels of retinol were associated with reduced bone mineral density in the femur. [13]
7. Cholesterol Reduction
An animal model found that total cholesterol was reduced in rats who were given beta-carotene, the plant form of vitamin A, over a course of six weeks. [14]
Another study found that a vitamin A deficient diet accelerated atherogenesis, the formation of plaque in the arteries of mice. [15]
8. Reproduction & Development
All vitamins are important for human health, but vitamin A is crucial when it comes to proper growth and development throughout all stages of our lives.
In particular, vitamin A is one of the best vitamins for women health.
Vitamin A deficiencies are associated with decreased immune function, higher morbidity and mortality and a greater risk of mother-to-child disease transmission. [16]
The American Pediatrics Association cites vitamin A as one of the most critical vitamins during pregnancy and the breastfeeding period, especially in terms of lung function and maturation. [17].
9. Tissue Health & Repair
Vitamin A aids cells in a process known as cellular differentiation. [18]
This is an integral part of wound healing, as cellular reproduction must occur for new tissue to grow.
Vitamin A also helps reduce the risk of wound infection, as it is essential to proper immune system function, and the nutrient helps manage inflammation that occurs after a wound is sustained. [19]
10. Kidney Stone Prevention
Kidney stones form when urine contains more crystal-forming substances such as calcium, oxalate and uric acid.
Research shows that vitamin A aids in the prevention of kidney stones. [20]
One study found that children deficient in vitamin A had greater levels of calcium oxalate cyrstals in their urine, which is an increased risk for stone formation. [21]
Signs of Vitamin A Deficiency
Now that we've discussed the important roles of vitamin A, let's review a few vitamin A deficiency symptoms.
Because vitamin A is essential for normal vision, healthy skin, immunity, bone growth and development we can assume that deficiencies would cause problems with all of these systems.
People with long-term malabsorption of fats are more susceptible to developing a vitamin A deficiency.
Those with leaky gut syndrome, celiac disease, autoimmune disorders, inflammatory bowel disease, pancreatic disorders or alcohol dependence are all at a higher risk of deficiency.
Some of the most common symptoms of a vitamin A deficiency include: [22]
- Xerophthalmia (dryness of the conjunctiva and cornea)
- Night blindness
- Bitot’s spots (buildup of keratin on the conjunctiva)
- Dry lips
- Thick or scaly skin
- Impaired immunity
- Stunted growth in children
Foods that Contain Vitamin A
So what foods are high in vitamin A?
First, remember that there are two sources of vitamin A: plant form (carotenoids) and animal form (retinol).
Carotenoids are colorful!
This means that foods with bright colors such as red, orange or yellow will have vitamin A.
Green foods also have an abundance of vitamin A. The green color comes from chlorophyll which allows plants to obtain energy from the sun.
This is also why the leaves turn colors in the fall. Basically all those shades of red, orange, and yellow are carotenoids. And as the chlorophyll degrades, it reveals the other colors that had been present all along.
So, to get vitamin A from plants, we should eat all the red, orange, yellow, and green vegetables.
When animals eat all these vegetables, the vitamin A is basically stored in our liver!
And just like we store vitamin A in our livers, so do fish, cows, chickens, and all the other animals.
So, the best source of animal-form vitamin A is liver. This is one of the benefits of Cod liver oil.
Aside from liver, the only other good source of vitamin A from animal foods are milk and eggs.
These are the two foods meant to nourish young animals, who need lots of vitamin A to grow correctly.
Now, you might think we could get vitamin A from plant foods and animal foods equally well.
But here's the thing: We need the animal form, retinol. We don't need the plant form, carotenoids.
So when we get vitamin A from plant foods, everything comes down to how good we are at converting the carotenoids to retinol.
Getting vitamin A from plant foods is pretty hard!
Here's a few things that can get in the way of conversion:
- Fiber
- Parasites
- Toxic Metals (mercury and lead)
- Iron Deficiency
- Zinc Deficiency
- Protein Deficiency
- Hypothyroidism
- Oxidative Stress Molecules from other Diseases
Here's what I recommend as the best way to get vitamin A:
- Eat 4 ounces of liver once a week, or eat a half ounce every day.
- If you tolerate eggs, eat up to three whole eggs a day.
- If you tolerate milk, consume up to three servings of full-fat dairy per day.
- Eat 3 or 4 cups of red, orange, yellow, and green vegetables a day.
- Don't go out of your way to eat a high-fat diet, but don't avoid fat either.
- To super-charge your vitamin A, use grass-fed butter and red palm oil for your added fats.
Vitamin A Supplements
If you can't meet the food recommendations, you should consider supplementing.
When supplementing, we need to start measuring because toxicity is possible.
Vitamin A is measured in “international units” or IU.
Cod liver oil that provides 3000 IU's per day from a brand that doesn't use synthetic vitamins is the most natural source.
You can also just take a vitamin A supplement.
If you're going to supplement, then take 3,000 IU a day, or 10,000 IU twice a week.
If you take more, you should work with a knowledgeable health care practitioner and make sure all your other nutrients are adequate to avoid imbalances (such as vitamin D, E and K).
Vitamin A Toxicity & Precautions
More is not better and vitamin A certainly has a dark side!
Too much vitamin a can hurt your bones, especially when you're deficient in vitamin D!
And while vitamin A is important for human development, toxicity can result in birth defects.
Additional symptoms of vitamin A toxicity include:
- Fatigue
- Hair Loss
- Upset stomach, nausea and vomiting
- Dry, peeling, itchy skin
- Cracked lips
- Headaches
Keep in mind that vitamin A is a fat-soluble vitamin and, therefore, needs to be consumed with fat in order to have optimal absorption.