Good timing on the study.

I was just eating a ton of carrots and sweet potatoes the last few months. I am now slowing down, stopping carrots completely.

Ran into skin problems, but they might have been due to other things like stress.

I am now decreasing my beta carotene consumption and increasing my retinol consumption.

I remember reading somewhere this might be due to B12 deficiency and that B12 was indeed recommended so that beta-carotene is used in a good way.

So the question is, if you do have adequate amount of B12 (dairy has plenty), is it ok to consume beta-carotene (carrots and sweet potatoes)?

Looks like I have to look for another source of carbs. I was consuming 3-4 pounds of sweet potatoes daily as well as carrots and a lot of leafy greens. This just goes to show the superiority of animal products.

I thought beta-carotene was what your body converted into vitamin A and that it only converts as much as it needs?

The question this raised for me, is if these caratenoids have anti-A activity.. perhaps the negative effect observed is from people with already minimal vitamin A (retinol) in their diet getting even worse activity.

I consume alot of carotene from sweet potato and pumpkin (~1kg a day) and this has been a good reminder to diversify my starch sources. My retinol status is quite good though (alot of liver in particular) and with some hope outweighed the negative effect on vitamin A produced by the caratenoids.

My first course of action is less sweet potato and more pumpkin.. while I look for some whiter starches (or purple :D ).

I'm going to have to look into this more, try to find what studies they're basing their conclusions on. It was my understanding that the cancer-causing beta-carotene was the one found in vitamins, NOT whole foods. This paragraph from the article seems to support my recollection: "The findings also might explain why, in a decades-old clinical trial, more people who were heavily *supplemented* with beta-carotene ended up with lung cancer than did research participants who took no beta-carotene at all. The trial was ended early because of that unexpected outcome."

In fact, the researchers aren't really talking about the effects of beta-carotene in whole foods. And it appears the whole purpose of their study is to understand why the artificial beta-carotene in the test on male smokers and asbestos workers created a higher incidence of lung cancer. So they can genetically engineer crops with increased beta-carotene for populations who are lacking vitamin A in their diets.

What I take away from this article is that the beta-carotene in our carrots and sweet potatoes is in no way the same as the beta-carotene used in the study that caused an increase in lung cancer. There is a danger when we isolate vitamins and minerals from the whole foods they came from because, as the researchers themselves stated, we don't fully understand how all the properties in a whole food work together to make it nourishing.

Could someone let us know which supplements contain beta-carotine? Thanks so much.

I would have assumed that artificial supplementation was the only way to take in harmful amounts, but the amounts of carrot/sweet potato mentioned above make me wonder.

Polar bear and beaver liver are not eaten because their vitamin a content is so hight as to be potentially lethal.

Check the nutritional info on the vegetables in question, perhaps here: http://ndb.nal.usda.gov/ and adjust your consumption accordingly.

here's a comment i found under another article on the same research http://www.nutraingredients.com/Research/Researchers-reveal-dark-side-to-high-beta-carotene-intake

The "shockwaves" referred to over a dated trial which used synthetic beta-carotene on already sick people (smokers) simply illustrate that old myths die hard. There is no evidence that the intake of natural mixed carotenes is in any way harmful.

And as for the current supposedly negative findings (if verified) would it not be a more reasonable view that such molecules are simply a self-limiting factor placed in foods by a wise Creator? In this way a possible oversupply of Vitamin A in the body is prevented. It explains the well-known fact that a high intake of natural mixed carotenes results only in health benefits. Because the above seems self-evident, one needs to ask the following question.

Is this report (as presented) just another attempt by vested interests to tarnish everything natural and to promote their own agenda?

Comment by Edward Jackson

Can we just all agree that anything in excess is bad? K thnx.

sad. I overdid kabocha pumpkins over the winter (a whole 2 pound pumpkin daily) and by spring everyone thought i had been spray tanning over the winter. i stopped the pumpkin for aesthetic reasons because unfortunately the shade looked like the spray tan gone bad. I really really miss my kabocha but now it appears i have more than an aesthetic reason to keep them at a distance. can never stop at just a little unfortunately.

Interesting. I wonder now then what I experienced was accidental. For about 2 months, I was on a yam-heavy safe starch diet. I consumed probably 400g+ of orange yams daily during that span (about 3 medium-sized orange American Southern yams).

I noticed my vision becoming very cloudy and blurry at night. I also occasionally (once or twice a week) take 2 tsps os Carlson's Cold Liver Oil, which has 850 IU of Vitamin A per teaspoon. When I did, I noticed my vision clearing up almost immediately. I also noted my sudden craving for the CLO (LOL) like an iron-deficient person craving ice.

Could this be that the excessive consumption of orange yams had anti-Vitamin A properties, resulting in paradoxical Vit A deficiency? The result is paradoxical, just like the linked article points out, because the beta carotene doesn't always convert to Vit A as assumed but blocks Vit A.

(But then do we really have to wonder? Taking calcium actually increases cardiovascular risk. Taking resveratrol in supplement form doesn't seem to lengthen longevity. Large intakes of fish oil could increase the risk of cancer.)

But the crux here is that this occurred when I was eating yams high in beta carotene, not any supplements. If so, this is very alarming indeed! In the above cases where vitamins had unintended effects, they were in the form of isolated nutrients.

Anyone on a high safe starch, orange yam diet experience vision anomalies like I did? If so, then, try taking some cod liver oil and see if the anomaly clears up. My tale seems to confirm the article's findings. Indeed, the beta carotene's anti-Vitamin A effect doesn't seem to be just limited to supplements. Confusing, huh? Before, we thought Beta Carotene was good for vision; now we're told, only up to a certain amount. But how do you know you've reached the tipping point? I was only trying to replicate the Kitavan diet in my experiment.

What does these all mean!!! Shall I take Anti oxidant pills with Beta Carotene or not!!!!