You likely know that Vitamin A is a crucial vitamin for your health – specifically your vision, immune system and cells.  Yet, you may not know that retinol – a type of Vitamin A – could spell trouble for your bones.  You could be getting more retinol than you need and putting your bones at risk for bone loss and hip fracture.  You’ll want to read about how to prevent this.

Retinol and Your Bone Health

When it comes to Vitamin A, there are 2 types:  Beta carotene – the precursor form of Vitamin A found in foods like sweet potatoes, carrots, mangos and kale.  Then there’s retinol naturally found in foods like liver, eggs, and fatty fish. Retinol is sometimes called “true vitamin A” as this form is readily available for your body to use in the form of retinyl esters. Beta carotene, however, must convert first to retinol (or vitamin A) before your body can use it.

“Retinoids” are retinol-like compounds that can be found in certain skin preparations for the treatment of acne and psoriasis.  Anti-aging skin creams also often contain retinoids in the form of retinoic acid, retinyl, palmitate, retinyl acetate, tretinoin.

If you eat high retinol (vitamin A) content foods, take a supplement with Vitamin A (instead of  beta carotene) and eat vitamin A-fortified cereals, or other foods, or use skin products with retinoids in them, you may be getting too much of the retinol form.

Too much retinol can become toxic.  Beta carotene forms, however, are safer, as your body only makes as much Vitamin A as it needs.  Yet, as both retinol and beta carotene are stored in the liver for future use, too much of both may become toxic to your liver.

Research has recently shown that too much retinol form Vitamin A can result in the production of osteoclasts – cells that break down bone – and put you at higher risk for bone loss and fracture, especially of the hip.  They have also found that too much Vitamin A may interfere with how Vitamin D works to preserve bone.  Too much Vitamin A has been linked to growth delay in children and teens as well.

Beta carotene, though, has not been linked to bone, or other parts of the body, problems.

How Much Retinol (Vitamin A) Should You Have?

The National Institute of Health’s Osteoporosis  and Related Bone Diseases National Research Center  warns against getting over 10,000 units of retinol (Vitamin A) a day.  For men and women over age 19, 3,000 units of retinol (vitamin A) is recommended per day for men, and 2,310 units for women.   Keep in mind that these are minimum daily requirements for the vitamin and that up to 10,000 can still be safe.

To judge how much retinol (vitamin A) you may be getting a day, here’s how much is contained in some common foods:

3 oz beef liver                      30,000 units

3 oz chicken liver                 13,920 units

Whole egg                                 280 units

2 oz egg substitute                 1,355 units

8 oz fortified milk                       500

4 oz fortified cereals            Up to 25% or more of RDA

3.5 oz of salmon                    About 497 units

As you can see, some single servings of certain foods, like beef and chicken liver, could give you much more than the recommended daily limit of retinol (vitamin A).  These foods also have a high fat content which helps better absorb the vitamin.  If you also take a supplement, and/or eat other foods with vitamin A in them, you could be getting way too much retinol in your diet and setting yourself up for bone loss as well as general toxicity.

My Recommendations

To ensure your good bone (and general) health, watch the retinol (vitamin A) content of the foods you eat.  Limit high retinol containing foods to once a week. Eating vitamin A fortified foods is not necessary on a daily basis unless you’re in danger of not being able to eat enough vitamin-rich foods in general.

Instead, eat foods rich in beta carotene like dark orange and green vegetables and fruits (carrots, cantaloupe, spinach, kale, sweet potatoes).  Researchers do agree that it is safer to get the precursor beta carotene form instead to allow your body to make retinol (vitamin A) as needed.   Be sure, too, that your multivitamin contains the beta carotene form rather than Vitamin A itself.

If you also use skin products that contain retinoids, ask your dermatologist about the amounts of retinol in them and coordinating the use of these with retinol intake from foods.

Stay Well,
Mark Bromson, M.D.

Vitamin content of salmon, http://www.nature.com/nature/journal/v147/n3722/abs/147267a0.html

Vitamin A http://ohioline.osu.edu/hyg-fact/5000/5551.html

Vitamin A and Bone Health, http://www.niams.nih.gov/Health_Info/Bone/Bone_Health/Nutrition/vitamin_a.asp#e

http://www.umm.edu/altmed/articles/beta-carotene-000286.htm