How much of a concern is eating too many phytotoxins from consuming 5-7 lbs of vegetables per day?

[Alex K Chen]

I'm just wondering, as I'm not sure if there's much precedent for it. One might wonder that phytotoxins are even more of a concern than the pesticides sprayed on these plants.

[Mechanism]

Edited

[Alex K Chen]

Hey Mechanism - it was also great to meet up with you in Boston.

 

I'm not necessarily concerned about the antioxidants inasmuch as I'm slightly concerned about the high number of plant toxins (plants tend to be super-high in metabolite diversity - and in fact, most neurotoxin exposure is directly through one's diet). Most people don't eat many vegetables to begin with, so this doesn't show up in most epidemiological data.

[Dean Pomerleau]

Mechanism,

 

Is this your concern?

 

I have been wondering the same thing, and for the link above The purported neutralization of exercise benefits has applicability especially for those ultra-exercises among us ( you know who you are!)

 

I must note that the Nutrition Diva article you point to above is critical of artificially concentrated doses of antioxidants, and is all for eating lots of fruits and vegetables (my emphasis):

 

Likewise, antioxidants serve a valuable function, so it’s not surprising that diets featuring antioxidant-rich foods like fruits, vegetables, nuts, and legumes are linked with good health and reduced disease. On the other hand, overwhelming the body with artificially concentrated doses of antioxidants appears to be of little benefit and may even be harmful.

 

As you know, I’m not a big fan of vitamin supplements. So this new take on free radicals doesn’t really change what I’ve been recommending all along. Spend your money on nutritious whole foods instead of supplements, stay active, avoid excessive stress, and keep your sense of humor.

 

Regarding exercise and antioxidants Mechanism wrote:

I have been wondering the same thing, and for the link above The purported neutralization of exercise benefits has applicability especially for those ultra-exercises among us ( you know who you are!)

 

Did you actually read the link you posted, and the reference it gives to a NY Times article on exercise and antioxidants? It seems not - for if you did you would have noticed that alleged neutralizing effects of antioxidants on the benefits of exercise is in the context of, what the NYT's article calls "a powerful, pharmaceutical-grade antioxidant that works in the body to halt the production of most free radicals" and that were injected into rats. From the study the NYT's article references [1], that antioxidant turns out to be allopurinol, a powerful pharmaceutical with many side effects used to treat gout. The allopurinol-treated rats didn't benefit from the upregulation of their innate antioxidant defenses normally induced by exercise. Big whoop. Do you really consider that relevant to a high fruit and veggie diet? Pretty disappointing for the NYT to even include that reference in a story about exercise and antioxidants if you ask me - but that's today's journalism for you... And bloggers like "Nutrition Diva" simply parrot the drivel they read elsewhere. Speaking of parrots. Alex, aka Mr. Quora question man, does parroting other people's answers have anything to do with your profile pic?

 

But back to exercise and antioxidants. The one human study the NYT article references was this 2009 study [2] published in PNAS with the provocative title "Antioxidants prevent health-promoting effects of physical exercise in humans". This study too tested isolated, high-dose antioxidants - in this case 1000 mg of vitamin C and 400 IU of just one Vitamin E isomer (α-tocopherol). It too found the benefits of exercise were blunted by the isolated antioxidant supplements. Again this doesn't seem at all relevant to a healthy, high fruit and vegetable diet with lots of antioxidants in natural amounts and balances, as the NYT also points out in the story:

 

But one message is clear. ‘‘The evidence suggests that antioxidants are not needed’’ by most athletes, even those training strenuously, said Li Li Ji, a professor of exercise physiology and nutritional science at the University of Wisconsin and one of the authors of the rat study. ‘‘The body adapts,’’ he said, a process that can, it seems, be altered by antioxidant supplements.

 

Another lesson: ‘‘Eat well,’’ he said. Although this is not yet proved, it seems likely, he continued, that antioxidants from foods, like blueberries, green tea and carrots, may work in tandem with the body’s natural antioxidant defenses better than those from supplements.

 

So concern that a healthy diet rich in antioxidants from whole plant foods will eliminate the benefits of exercise seem terribly overblown and ill-founded based on available evidence. In fact, quite the contrary. Even high doses of individual vegetables, and even just their juice (e.g. beets) can provide big benefits for cardiovascular performance and recovery from strenuous exercise. 

 

Alex, regarding concern over natural plant toxins from eating too many vegetables, it's certainly not outside the realm of possibility, and you are right that so few people eat lots of F&V long-term that we can't entirely rule out such a possibility. That's one reason I eat an extremely diversified plant-based diet. That way, any individual, especially-harmful plant toxin I'm getting will be in small quantities, and more apt to upregulate my bodies natural defenses than to compromise or overwhelm them.

 

Which is an interesting perspective to think about. Just like exercise, one important reason fruits and vegetables are thought to be healthy is because of their hormetic effect. They contain mild toxins, which upregulate the body's defenses, just like both CR & exercise, which also stress the body and cause it to be more vigilant and thorough in its maintenance & repair processes. Eating a diverse, plant-based diet without too much of any one food (and therefore plant toxin) should serve as this same kind of mild hormetic stress that is quite beneficial, rather than harmful. To learn more, here is a thread on this xenohormetic effects of plants. 

 

--Dean

 

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[1] J Physiol. 2005 Aug 15;567(Pt 1):113-20. Epub 2005 Jun 2.

 

Decreasing xanthine oxidase-mediated oxidative stress prevents useful cellular

adaptations to exercise in rats.

 

Gomez-Cabrera MC(1), Borrás C, Pallardó FV, Sastre J, Ji LL, Viña J.

 

Author information: 

(1)Catholic University of Valencia, Spain.

 

Reactive oxygen or nitrogen species (RONS) are produced during exercise due, at

least in part, to the activation of xanthine oxidase. When exercise is exhaustive

they cause tissue damage; however, they may also act as signals inducing specific

cellular adaptations to exercise. We have tested this hypothesis by studying the 

effects of allopurinol-induced inhibition of RONS production on cell signalling

pathways in rats submitted to exhaustive exercise. Exercise caused an activation 

of mitogen-activated protein kinases (MAPKs: p38, ERK 1 and ERK 2), which in turn

activated nuclear factor kappaB (NF-kappaB) in rat gastrocnemius muscle. This

up-regulated the expression of important enzymes associated with cell defence

(superoxide dismutase) and adaptation to exercise (eNOS and iNOS). All these

changes were abolished when RONS production was prevented by allopurinol. Thus we

report, for the first time, evidence that decreasing RONS formation prevents

activation of important signalling pathways, predominantly the MAPK-NF-kappaB

pathway; consequently the practice of taking antioxidants before exercise may

have to be re-evaluated.

 

DOI: 10.1113/jphysiol.2004.080564 

PMCID: PMC1474177

PMID: 15932896

 

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[2] Proc Natl Acad Sci U S A. 2009 May 26;106(21):8665-70. doi:

10.1073/pnas.0903485106. Epub 2009 May 11.

 

Antioxidants prevent health-promoting effects of physical exercise in humans.

 

Ristow M(1), Zarse K, Oberbach A, Klöting N, Birringer M, Kiehntopf M, Stumvoll

M, Kahn CR, Blüher M.

 

Author information: 

(1)Department of Human Nutrition, Institute of Nutrition, University of Jena,

Jena D-07743, Germany. mristow@mristow.org

 

Free full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1474177/

 

Exercise promotes longevity and ameliorates type 2 diabetes mellitus and insulin 

resistance. However, exercise also increases mitochondrial formation of

presumably harmful reactive oxygen species (ROS). Antioxidants are widely used as

supplements but whether they affect the health-promoting effects of exercise is

unknown. We evaluated the effects of a combination of vitamin C (1000 mg/day) and

vitamin E (400 IU/day) on insulin sensitivity as measured by glucose infusion

rates (GIR) during a hyperinsulinemic, euglycemic clamp in previously untrained

(n = 19) and pretrained (n = 20) healthy young men. Before and after a 4 week

intervention of physical exercise, GIR was determined, and muscle biopsies for

gene expression analyses as well as plasma samples were obtained to compare

changes over baseline and potential influences of vitamins on exercise effects.

Exercise increased parameters of insulin sensitivity (GIR and plasma adiponectin)

only in the absence of antioxidants in both previously untrained (P < 0.001) and 

pretrained (P < 0.001) individuals. This was paralleled by increased expression

of ROS-sensitive transcriptional regulators of insulin sensitivity and ROS

defense capacity, peroxisome-proliferator-activated receptor gamma (PPARgamma),

and PPARgamma coactivators PGC1alpha and PGC1beta only in the absence of

antioxidants (P < 0.001 for all). Molecular mediators of endogenous ROS defense

(superoxide dismutases 1 and 2; glutathione peroxidase) were also induced by

exercise, and this effect too was blocked by antioxidant supplementation.

Consistent with the concept of mitohormesis, exercise-induced oxidative stress

ameliorates insulin resistance and causes an adaptive response promoting

endogenous antioxidant defense capacity. Supplementation with antioxidants may

preclude these health-promoting effects of exercise in humans.

 

DOI: 10.1073/pnas.0903485106 

PMCID: PMC2680430

PMID: 19433800

[Mechanism]

Edited

[Dean Pomerleau]

Mechanism,

 

Yes, modern agriculture and worldwide food transportation, refrigeration and supermarkets enables us to eat diets richer in nutrients than any humans (or creatures for that matter) have eaten in the history of the planet. Heck, we can get fresh berries in the middle of winter for Pete's sake, something that wasn't possible even 10 or 15 years ago. Is eating a pint of fresh (or frozen) blueberries a day doing to kill us all after 30 years? Possibly, but given the available evidence, I'm not betting on it.

 

The best evidence we have is that eating lots of fruits and vegetables are healthy for you, without apparent ceiling effects (although probably some asymptotic effect one would presume). So you could eat less nutritious foods to avoid some ill-defined and hypothetical safe upper limit for fruits and veggies. But you gotta eat something - and whatever you choose you've got to worry about toxins, antinutrients or other harmful sh*t in the foods you eat instead of F&Vs. I choose instead to simply eat a wider variety of fruits and veggies, and thereby avoid putting too many eggs in any one (or a few) food basket(s).

 

Regarding fiber - the evidence suggests our miscenic ancestors (rather than the very short and recent paleolithic era) ate over 100g of fiber per day for millions of years as this recent Dr. Greger video discusses. While they didn't live as long as we do, so the super-long-term effects of high fiber is a bit uncertain, at least our body should be adapted to this sort of very high fiber diet from our ancestral heritage.

 

--Dean

[Pablo Stafforini]

The best evidence we have is that eating lots of fruits and vegetables are healthy for you, without apparent ceiling effects

 

Hi Dean,

 

What is the evidence that there are no ceiling effects for the health benefits of fruits and vegetables? I don't mean to dispute the claim—I'm just trying to educate myself. Thanks!

 

Pablo

[Dean Pomerleau]

Pablo,

 

What is the evidence that there are no ceiling effects for the health benefits of fruits and vegetables? I don't mean to dispute the claim—I'm just trying to educate myself. Thanks!

 

No problem good question. Although I'll note that I said (new emphasis) "without apparent ceiling effects, (although probably some asymptotic effect one would presume)." Important qualifiers.

 

Here is discussion of the "Near Perfect Diet" study (PMID 11288049) that used the largest quantity of fruits and veggies I've seen in any human diet intervention trial - 11 lbs or 63 servings per day. The authors observed no adverse effects (except big poops!) and dramatic improvements in cardiovascular risk markers, even relative to other healthy diets tested. But of course that was only a 2-week study, so not much evidence can be drawn from it. Heck, many of us have been eating that much F&V for many years without adverse effects.

 

When I said "without apparent ceiling effects" for F&V consumption, I meant that I've yet to come across any studies in humans or animals that have found or even suggest that there is a point beyond which extra servings of a variety of fruits and veggies (or fiber) become detrimental to health or longevity. Everything I've seen points to "the more the better". But again, I'm not trying to argue it's inconceivable that such a ceiling could exist. 

 

In short, you asked "What is the evidence that there are no ceiling effects...?". What I was claiming was "There is no evidence that there is a ceiling effect...". An important distinction. Absence of evidence (my statement) is not evidence of absence (your question).

 

But again, you gotta eat something. In my book, it might as well be extra fruits & veggies, along with healthy servings of nuts, seeds, legumes, tubers, and unrefined whole grains.

 

--Dean

[Alex K Chen]

Thanks for the replies, everyone! :) Yeah, I tend to go for low cost so I don't diversify much (so most of what I eat is lettuce/cabbage/carrots/broccoli/cauliflower). Sometimes I wonder why pesticides don't trigger the same sort of xenohormesis and seem to have such robust neurotoxic effects instead..

 

I found it interesting when Pete Estep mentioned that he didn't know of any cultures that ate such a vegetable-heavy diet.