In yesterday's blog, I wrote about Chris Masterjohn's presentation about the fat-soluble vitamins A, D, and K and how to optimize health with these vitamins.
So, why do we need vitamin A anyway? We need vitamin A, a fat-soluble vitamin, for bone growth, reproduction, immune function, hormone synthesis and regulation, and vision. If you don't get enough vitamin A, you may experience reduced night vision, dry eyes, and susceptibility to respiratory infections.
I calculated my Daily Recommended Intake (RDI) by using this very cool tool http://fnic.nal.usda.gov/fnic/interactiveDRI/
Vitamin Recommended Intake per day 700mcg
Tolerable UL Intake per day 3000mcg
The RDI for vitamin A is given in retinol activity equivalents (RAE). You can get vitamin A from animal or plant sources but the body treats these differently. Vitamin A from animal foods or fortified foods is called retinol. This is the preformed vitamin A, that is highly available to the body, whereas the vitamin A from plant sources, called carotenoids, have to be converted to the active form. 12 mcgs of beta-carotene equals 1 mcg of retinol. Supplements don't use RAEs, instead you will see international units (IU). 1 RAE is 3.33 IUs, so my RDI for Vitamin A in IUs would be 2333. Complicated isn't it? So better stick to foods.
If you are eating the recommended five servings of fruits and vegetables per day, you should be able to get about half of your vitamin A need covered. Plant sources of vitamin A include carrots, spinach, and apricots. You would also want to eat good sources of preformed vitamin A (retinol) such as eggs, whole milk, liver, and fortified skim milk or cereals.
However, some people have a genetic variation, a single nucleotide polymorphism (SNP) A379V and/or R267S which cause them to be less efficient in converting carotenoids to retinol. I have been blessed with both SNPs which reduce my ability to convert carotenoids to retinol by about 69%
Before I did the genetic test and found out about these SNPs, I noticed that my night vision was decreasing, and whenever I contracted a respiratory infection, it would take me forever to recover from it. I suspected vitamin A deficiency but couldn't figure out how I could be deficient, eating a pretty decent diet. I take cod liver oil now which gives me vitamin A and D and some essential fatty acids, nicely packaged as a food. I believe food is preferable to a pill. It turns out that taking cod liver oil is a much safer and effective way to supplement with these fat-soluble vitamins which can be toxic if taken in very large doses as individual supplements in pill form.
Most of you won't know if you have this genetic variation, so let's just say you don't have it. Are you sure, you are getting enough vitamin A? If not, perhaps it wouldn't hurt to take a spoon full of cod liver oil every now and then.
Here is more information about the vitamin A SNPs A379V and R267S http://snpedia.com/index.php/Rs12934922
Chris Masterjohn, a PhD in Nutritional Sciences, blogs on "The Daily Lipid" at http://blog.cholesterol-and-health.com/ His website http://www.cholesterol-and-health.com/cholesterol-and-health.html is full of well researched information.
So, why do we need vitamin A anyway? We need vitamin A, a fat-soluble vitamin, for bone growth, reproduction, immune function, hormone synthesis and regulation, and vision. If you don't get enough vitamin A, you may experience reduced night vision, dry eyes, and susceptibility to respiratory infections.
I calculated my Daily Recommended Intake (RDI) by using this very cool tool http://fnic.nal.usda.gov/fnic/interactiveDRI/
Vitamin Recommended Intake per day 700mcg
Tolerable UL Intake per day 3000mcg
The RDI for vitamin A is given in retinol activity equivalents (RAE). You can get vitamin A from animal or plant sources but the body treats these differently. Vitamin A from animal foods or fortified foods is called retinol. This is the preformed vitamin A, that is highly available to the body, whereas the vitamin A from plant sources, called carotenoids, have to be converted to the active form. 12 mcgs of beta-carotene equals 1 mcg of retinol. Supplements don't use RAEs, instead you will see international units (IU). 1 RAE is 3.33 IUs, so my RDI for Vitamin A in IUs would be 2333. Complicated isn't it? So better stick to foods.
If you are eating the recommended five servings of fruits and vegetables per day, you should be able to get about half of your vitamin A need covered. Plant sources of vitamin A include carrots, spinach, and apricots. You would also want to eat good sources of preformed vitamin A (retinol) such as eggs, whole milk, liver, and fortified skim milk or cereals.
However, some people have a genetic variation, a single nucleotide polymorphism (SNP) A379V and/or R267S which cause them to be less efficient in converting carotenoids to retinol. I have been blessed with both SNPs which reduce my ability to convert carotenoids to retinol by about 69%
Before I did the genetic test and found out about these SNPs, I noticed that my night vision was decreasing, and whenever I contracted a respiratory infection, it would take me forever to recover from it. I suspected vitamin A deficiency but couldn't figure out how I could be deficient, eating a pretty decent diet. I take cod liver oil now which gives me vitamin A and D and some essential fatty acids, nicely packaged as a food. I believe food is preferable to a pill. It turns out that taking cod liver oil is a much safer and effective way to supplement with these fat-soluble vitamins which can be toxic if taken in very large doses as individual supplements in pill form.
Most of you won't know if you have this genetic variation, so let's just say you don't have it. Are you sure, you are getting enough vitamin A? If not, perhaps it wouldn't hurt to take a spoon full of cod liver oil every now and then.
Here is more information about the vitamin A SNPs A379V and R267S http://snpedia.com/index.php/Rs12934922
Chris Masterjohn, a PhD in Nutritional Sciences, blogs on "The Daily Lipid" at http://blog.cholesterol-and-health.com/ His website http://www.cholesterol-and-health.com/cholesterol-and-health.html is full of well researched information.
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