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March 15, 2007

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There are lots of great things being discovered in this respect, and yes, the evidence is there to say that this does indeed help.

Great post.

Barry
http://www.amdsupport.ca/

Paul,

It has been reported that at higher doses, beta-carotene can cause yellowing of the palms, hands and soles of feet. This is reversible, however. Other side effects that have been reported are dizziness, diarrhea and joint pain. Also, there is some evidence that beta-carotene may increase cardiovascular mortality in patients who smoke (these patients also had previous heart attacks, however). I wonder if the study took this into consideration.

I always thought vitamin A was mostly involved in visual acuity, whereas AMD is more of a pathological breakdown of photoreceptors in the eye. Either way, the results of this study show pretty conclusively that 50mg of beta-carotene every other day does not help prevent AMD. I'd also like to know what side effects people had at this dose - any skin color changes or things that might prevent higher doses? Still, this seems a little disappointing in the fight against AMD.

My mom is constantly telling me to eat my carrots for my vision, and then recently she asked me if I knew if they actually did help. This study doesn’t show a significant difference to prove the effectiveness of beta-carotene. I agree with Emily P. in that maybe the supplements need to be taken over a longer period of time with a younger test group.

Perhaps this study would've been more effective if the test population were younger. Although age 40 is still relatively young, it is possible that preventative measures might need to be introduced in one's youth in order to be fully effective.

My momma always told me to eat carrots to make my vision better...I've had 20/20 vision for 23 years - not sure if it has anything to do w/the carrots though. I've also heard that beta-carotene helps strengthen your night vision...anyone know if this is true?

I have heard of lutein being used for potential vision benefits. It's actually found in a small area of the retina called the macula. Supposedly, lutein is supposed to, in a sense, prevent oxidative stress on the eyes that could eventually cause AMD.

Also, if beta-carotene doesn't actually aid in the prevention of AMD (at that particular dose), does it have any other benefits for ocular health? Where did everyone get the idea that it did?

I also read up on this clinical trial with beta-carotene. I was quite surprised that beta-carotene supplementation demonstrated no statistically significant benefit over those who didn't take it when it came to AMD. I think, like someone else mentioned, perhaps a greater dose was necessary? Also, has anyone heard about lutein being studied for potential eye benefits?

The body converts Beta-carotene into Vitamin A, which is important because Vitamin A deficiency is a leading cause of blindness. However, beta-carotene will only help your vision if your body is deficient in vitamin A. Studies have shown that eating foods containing vitamin A & beta-carotene can improve vision for people who have vitamin A deficiency with fairly poor vision. It's improtant to keep in mind that the high levels of beta-carotene that produced such studies were obtained from vitamin and mineral supplements, and it would be very difficult to reach the same level of intake by eating lots of carrots. Also, there is no evidence that excessive carrot consumption prevents macular degeneration or other diseases affecting vision at any age. Note that zeaxanthin and lutein, which are also found in carrots, help prevent cataracts.

From the looks of it, this was a well-designed study that evaluated the use of beta-carotene in preventing AMD. It does seem to indicate that beta-carotene alone would neither decrease nor increase the risk of AMD, but many vitamins/supplements work synergistically with others for optimum results. I am not up on all of the relationships, but maybe beta-carotene needs to be given with vitamin C or zinc to get the best effect.

Also, maybe a study should be done with a range of doses. 50mg per day didn’t seem to have any effect, but what about 60mg or 75mg per day? Another option would be to do a study comparing patients who receive beta-carotene in supplemental form to increased beta-carotene consumption from foods. This study just ruled out one dosage of supplemental beta-carotene alone in preventing AMD. It may need further study to rule it out altogether.

Beta-carotene has long been rumored to stave off macular degeneration. This seemingly well-designed study seems to bring into question the veracity of that claim. The JAMA Patient Page on AMD states that Caucasians, smokers and the elderly are predisposed to develop the condition. Did the authors of this study screen participants for these predispositions? Did any of the study participants have family members who also experienced vision problems?

More generally, I wonder if the participants in the study practiced a healthy lifestyle. Good nutrition and regular exercise are not guaranteed to prevent the onset of the disease, but they do promote a state of wellness that increases the individual's chance of maintaining good health.

I’d like to see more studies on beta-carotene intake and macular degeneration that offer insight to demographic and lifestyle factors that may impact the onset of this disease.

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