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mom613

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Posts: 2
Reply with quote  #1 
Hi,
I'm making my way through The Science of Skinny book and am enjoying it immensely. I had a question on your statement that synthetic vitamin A is damaging. (I don't recall the exact wording.) I am on a regimen of 15,000 IU of Vitamin A daily due to a degenerative retinal condition. Can you explain what the damaging impact of vitamin A is and is there any steps I can take to minimize it. (Currently the only treatment of my condition is this regimen which has been found to slow the deterioration of vision.) Thanks.
deemccaffrey

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Posts: 1,159
Reply with quote  #2 
Hi Mom 613,

Thanks for posting, and welcome to the forum!  

I believe you are referring to a sentence on page 147 that states "Large amounts of beta-carotene in supplements have posed risks to some people, but small amounts used as food additives are safe."  

Vitamin A is essential for normal vision, bone growth, cell division, and proper immune function. However, if you get too much of one form of this vitamin, you could actually cause yourself harm.

There are two main forms of vitamin A: 

Retinol, a ready-to-use form (sometimes referred to as "pre-formed vitamin A"). Primary sources are certain animal products like eggs, milk, butter and cheese, liver, salmon, cod liver oil, fortified margarine, fortified low-fat dairy products, other fortified foods, and supplements. Sixty-six percent of all vitamin A intake in the American diet comes from retinol or pre-formed vitamin A added to foods (mostly as retinyl palmitate). Vitamin A is also found in supplements (as retinyl palmitate and retinyl acetate). The tolerable upper limit for retinol is 10,000 IU daily.  Exceeding this is what causes many health problems (see below).

Carotenoids, including Beta-carotene, a precursor (or "provitamin") found only in plant foods that the body can convert into vitamin A. Primary sources are green and yellow vegetables, especially carrots. Thirty three percent of all vitamin A intake in the American diet comes from the carotenoids in foods. Mixed carotenoids (a blend of different carotenoids) can be taken as a supplement whereas multiple vitamins only contain one carotenoid: beta-carotene. There is no tolerable upper limit for carotenoids. The body can handle high amounts of carotenoids with no harmful effects.

Research in adults has shown that taking in too much retinol on an ongoing basis is associated with liver abnormalities, central nervous system disorders, and lower bone mineral density that might increase osteoporosis risk. Both human and animal studies show that a higher vitamin A intake interferes with bone metabolism. Specifically, excess retinol suppresses bone-building activity, stimulates bone breakdown, and interferes with vitamin D’s role in calcium absorption and regulation.

It is important to note that all vitamin A toxicity issues pertain to retinol intake (in foods and supplements containing retinol, retinyl palmitate, or retinyl acetate) and NOT food-based carotenoid intake (like beta-carotene) or supplements that provide vitamin A in the form of carotenoids or beta-carotene.

If you are taking a 15,000 IU supplement of vitamin A, you should make sure it is not in the form of retinol, retinyl palmitate, or retinyl acetate.

The best way to ensure that your body has access to plenty of vitamin A without becoming overloaded is to get most of your vitamin A in the form of beta-carotene, which is plentiful in dark green and orange fruits and vegetables, such as spinach, carrots, sweet potatoes, pumpkin, cantaloupe, and kale, perhaps with lesser amounts coming from animal sources of retinol, such as whole milk, whole eggs, butter, and cheese.

And I may note that it's not just a lack of vitamin A, but a lack of many other antioxidants in the diet that puts the retina at risk, causing premature aging and deterioration. Therefore, consuming generous amounts of the body's principle protective antioxidants, namely vitamins C and E, the carotenes, and small amounts of the mineral, selenium, will help protect your sight. This is why dietary sources of vitamins are better for you than synthetic supplements.

It's not that difficult to get 15,000 IU just from your diet.  Here's a chart that shows how much vitamin A is in certain foods:

Animal Sources of Vitamin A (as retinol)

 Serving

Vitamin A
(IU)

%RDA
Women

Turkey giblets

½ cup

25,950

1120%

Beef liver

3 oz

22,175

960%

Cod liver oil

1 tsp

4,500

200%

Chicken liver

3 oz

4,255

185%

Butter

1 tbsp

355

15%

Egg

1 large

335

15%

Salmon

3.5 oz

324

15%

Cheddar cheese

1 oz

284

12%

Whole milk

1 cup

250

10%

 

 

 

 

Plant Sources of Vitamin A
(as carotenoids)

 Serving

Vitamin A
(IU)

%RDA
Women

Sweet potato

1 med.

28,058

1215%

Pumpkin, canned

½ cup

19,065

825%

Carrots, cooked

½ cup

13,418

580%

Spinach, cooked

½ cup

11,458

495%

Collards, cooked

½ cup

9,769

420%

Kale, cooked

½ cup

9,558

415%

Turnip greens, cooked

½ cup

8,828

380%

Winter squash

½ cup

5,353

230%

Red peppers, cooked

½ cup

3,738

160%

Cantaloupe

1 cup

5,411

235%

Lettuce, Green Leaf

1 cup

4,147

180%

Green peas, cooked

1 cup

3,360

145%

Apricots, dried

3

2,022

88%

Butternut squash, cooked

1⁄2 cup

1,900 IU

80%

Broccoli, cooked

½ cup

1,208

52%


Also, you may want to consider getting a juicer so that you can drink fresh carrot juice.  One 8-oz. glass of carrot juice contains a whopping 20,000 mcg of vitamin A (that's 33,340 IU !!!).  It has been known to improve people's eyesight tremendously.  Plus, when you drink carrot juice you get dozens of other carotenes, not just the beta form. Freshly made from your own juicer, raw carrot juice tastes good and provides many other valuable nutrients. 

~Best,
Dee




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Dee McCaffrey
http://www.processedfreeamerica.org
mom613

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Posts: 2
Reply with quote  #3 
Thank you so much for your detailed response. I am definitely going to take the time to print it out and read it more carefully later. I just want to follow up with another question. My Dr had brushed off the option of taking vitamin A through food- perhaps becuase he did not think it feasible to really make sure I would get the 15,000 IU every day, or because it would have to be the specific type of vitamin A (i think it's not the beta-carotene, it's the other type that was used in his study.)
At any rate, I have been advised that I can not get pregnant on the 15,000 IU of vitamin A regimen due to the risk of birth defects. Do you feel the risk is different if I were to get the daily vitamin A through food intake?
Thanks.
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