What is the adequate intake of antioxidants ?
I know that ORAC (Oxygen Radical Absorbance Capacity) values are measured only in vitro and it may not produce the same effects in the human body, but some believe that ORAC does provide valuable information.
I started researching on the internet for a adequate intake of ORAC and I found 2 different recommendations:
1. Some say 8000-11000 umol:
https://nutritionfacts.org/2014/12/04/how-to-get-enough-antioxidants-each-day/
https://researchgate.net/Plasma_Antioxidant_Capacity_Changes_Following_a_Meal
2. Others (Dr. Ronald Prior of the USDA) say that intakes greater then 5000 umol are excreted in the urine:
https://naturalbalancefoods.co.uk/community/healthy-living/the-orac-system/
Who can I believe ? 
I apologise for my misspellings, as English is not my native language.
Comments
Hi @Marus
This is a great topic.... I wish I could provide you with a more concrete answer. Dr. Greger does do a good job of summarizing studies and I agree with what he's saying about the quality of fruits and vegetables. However, I also don't think we have an unlimited ability to use antioxidants (as such physiological processes would take time) per the second article you shared.
My very general, conservative recommendation would be to eat as many fruits and vegetables as you can that are high in antioxidants; we've never seen detrimental health effects from this. However, definitely avoid supplementing with antioxidants since we know that an antioxidant at high doses can act like a pro-oxidant.
Kind regards,
Susan Macfarlane, MScA, RD
Registered Dietitian Nutritionist
cronometer.com
As always, any and all postings here are covered by our T&Cs:
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I read that cooked foods lose as musch as 90% of it's antioxidants. But then, it is talked about the fact that green tea is full of antioxidants. How can it have so many antioxidants when it's made with boiled water, and that destroy them ?
I apologise for my misspellings, as English is not my native language.
@Marus
I don't have a reference for how much cooking destroys antioxidants, but I do know that it can depend on the food as well as the type of antioxidant being measured. For example, carotenoids become more bioavailable (or easier to absorb) with cooking.
The most important factor when it comes to loss of antioxidants is the amount of time a food is exposed to heat. Low-cooking methods are preferred, but not if you have to cook them for a very long time. Try to find the middle ground between time and temperature.
Kind regards,
Susan Macfarlane, MScA, RD
Registered Dietitian Nutritionist
cronometer.com
As always, any and all postings here are covered by our T&Cs:
https://forums.cronometer.com/discussion/27/governing-terms-and-disclaimer
@Marus
Antioxidants is a broad and somewhat ambiguous category of compounds. Some are genuine nutrients, like vitamin E, vitamin C, carotenoids, and glutathione. But then there are polyphenolic compounds and phytochemicals in plants that act as antioxidants for the plant, but not for us. When we ingest these compounds, the body upregulates metabolic pathways that facilitate their disposal. Virtually all non-nutritive antioxidant compounds from plants act as pro-oxidants in the body. I mean, they aren't even designed to directly augment the human antioxidant defense system. Our bodies view them as foreign and gets rid of them.
However, this is actually a good thing in most cases. If you chronically ingest small doses of these compounds, like from eating fruits and vegetables every day, your body will build up its own defenses over time. These compounds indirectly augment the body's antioxidant defense system by stressing the body, and thus causing the body to increase it's own antioxidants like glutathione. This process is called hormesis. It's generally accepted in the literature that this is the mechanism by which these plant compounds exert their benefits.
As an aside, I actually suspect that people on the carnivore diet will have issues related to oxidative stress down the road. Largely due to the fact that their diet lacks virtually all relevant hormetic stressers. It's my suspicion that those people will walk away from that diet with lower overall glutathione status than when they started, haha.
First I was afraid, I was petrified...
when you said that polyphenolic compounds and phytochemicals are not anitoxidants for humans. I read a lot that flavonoids and other stuff like that are antioxidants, and are good for us. I was afraid that you don't recommend fruits and vegetables... 
But then I understud when you explained how it works.
I apologise for my misspellings, as English is not my native language.