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More Intimations of a Human Longevity Dependence on Atmospheric CO2 Concentration
Volume 7, Number 13: 31 March 2004

We apologize at the outset of this brief editorial for engaging in what may seem to some to be little more than wishful thinking.  At this point in time, in fact, we admit that it is essentially just that.  We excuse ourselves, however, in the hope that it may spur someone with the means to do so to more thoroughly investigate that about which we herein muse; for speculation is a great impetus to the building of hypotheses that drive experiments that ultimately reveal new truths.

A group of twelve scientists (Wentworth et al., 2003) has recently reported they have found "evidence for the production of ozone in human disease," specifically noting that "signature products unique to cholesterol ozonolysis are present within atherosclerotic tissue at the time of carotid endarterectomy, suggesting that ozone production occurred during lesion development."  Why is this important?

As Marx (2003) describes it, "researchers think that inflammation of blood vessels is a major instigator of plaque formation," that "ozone contributes to plaque formation by oxidizing cholesterol," and that the new findings "suggest new strategies for preventing atherosclerosis."  Further, according to Marx, Daniel Steinberg of the University of California, San Diego, adds that it's still too early to definitively state whether ozone production in plaques is a major contributor to atherosclerosis; but she writes that he expresses his confidence that "once we know for sure, we'll know which antioxidants will work" in suppressing plaque formation.

Consider, in this regard, the strawberry.  Wang et al. (2003) report that strawberries are especially good sources of natural antioxidants, citing the work of Wang et al. (1996) and Heinonen et al. (1998).  They say that "in addition to the usual nutrients, such as vitamins and minerals, strawberries are also rich in anthocyanins, flavonoids, and phenolic acids," and that "strawberries have shown a remarkably high scavenging activity toward chemically generated radicals, thus making them effective in inhibiting oxidation of human low-density lipoproteins (Heinonen et al., 1998)."  They also note that Wang and Jiao (2000) and Wang and Lin (2000) "have shown that strawberries have high oxygen radical absorbance activity against peroxyl radicals, superoxide radicals, hydrogen peroxide, hydroxyl radicals, and singlet oxygen."  And they say that "anthocyanins have been reported to help reduce damage caused by free radical activity, such as low-density lipoprotein oxidation, platelet aggregation, and endothelium-dependent vasodilation of arteries (Heinonen et al., 1998; Rice-Evans and Miller, 1996)."

So should we all eat lots of strawberries to keep our arteries hale and hearty?  It probably wouldn't hurt any; but our reason for citing this information is that Wang et al. (2003) have recently demonstrated that enriching the air with carbon dioxide increases both the concentrations and activities of many of these helpful substances.  They determined, for example, that strawberries had higher concentrations of ascorbic acid and glutathione when grown in CO2-enriched environments.  They also learned that "an enriched CO2 environment resulted in an increase in phenolic acid, flavonol, and anthocyanin contents of fruit."  For nine different flavonoids, in fact, there was a mean concentration increase of 55% in going from the ambient atmospheric CO2 concentration to ambient + 300 ppm CO2, and a mean concentration increase of 112% in going from ambient to ambient + 600 ppm CO2.  Also, they report that "high flavonol content was associated with high antioxidant activity."

There is little reason to doubt that similar concentration and activity increases in the same and additional important phytochemicals in other food crops would occur in response to similar increases in the air's CO2 concentration.  Indeed, the aerial fertilization effect of atmospheric CO2 enrichment is a near-universal phenomenon that operates among plants of all types, and it is very powerful.  Since the dawning of the Industrial Revolution, for example, the work of Mayeux et al. (1997) and Idso and Idso (2000) suggests that the concomitant historical increase in the air's CO2 content has led to mean yield increases of approximately 70% in C3 cereals, 28% in C4 cereals, 33% in fruits and melons, 62% in legumes, 67% in root and tuber crops, and 51% in vegetables, as described in our Editorial of 11 Jul 2001.  Hence, there must have been significant concomitant increases in the concentrations and activities of the various phytochemicals in these foods that act as described by Wang et al. (2003).

If we are right on this point, this phenomenon should have had a major impact on human health and, consequently, life span over the past two centuries; and when we look at the data pertaining to this subject, we see that something has definitely done so.  Oeppen and Vaupel (2002), for example, report that "world life expectancy more than doubled over the past two centuries, from roughly 25 years to about 65 for men and 70 for women."  What is more, they note that "for 160 years, best-performance life expectancy has steadily increased by a quarter of a year per year," and they emphasize that this trend "is so extraordinarily linear that it may be the most remarkable regularity of mass endeavor ever observed," which clearly implicates the operation of some simultaneously-occurring worldwide phenomenon as its cause.

Could that phenomenon have been the historical increase in the air's CO2 content?  We believe that it has clearly played some part in the remarkable extension of human life span that has accompanied the progression of the Industrial Revolution, but just how large a part is difficult to determine.  More research into the effects of atmospheric CO2 enrichment on various health-promoting substances in the foods we eat is definitely needed to help resolve this important question.  And with the stakes being as high as they are -- with some people wanting to curtail what may be bringing us huge health benefits, i.e., anthropogenic CO2 emissions -- that research should be a very high priority item.

Sherwood, Keith and Craig Idso

Heinonen, I.M., Meyer, A.S. and Frankel, E.N.  1998.  Antioxidant activity of berry phenolics on human low-density lipoprotein and liposome oxidation.  Journal of Agricultural and Food Chemistry 46: 4107-4112.

Idso, C.D. and Idso, K.E.  2000.  Forecasting world food supplies: The impact of the rising atmospheric CO2 concentration.  Technology 7S: 33-56.

Marx, J.  2003.  Ozone may be secret ingredient in plaques' inflammatory stew.  Science 302: 965.

Mayeux, H.S., Johnson, H.B., Polley, H.W. and Malone, S.R.  1997.  Yield of wheat across a subambient carbon dioxide gradient.  Global Change Biology 3: 269-278.

Oeppen, J. and Vaupel, J.W.  2002.  Broken limits to life expectancy.  Science 296: 1029-1030.

Rice-Evans, C.A. and Miller, N.J.  1996.  Antioxidant activities of flavonoids as bioactive components of food.  Biochemical Society Transactions 24: 790-795.

Wang, S.Y. and Jiao, H.  2000.  Scavenging capacity of berry crops on superoxide radicals, hydrogen peroxide, hydroxyl radicals, and singlet oxygen.  Journal of Agricultural and Food Chemistry 48: 5677-5684.

Wang, S.Y. and Lin, H.S.  2000.  Antioxidant activity in fruit and leaves of blackberry, raspberry, and strawberry is affected by cultivar and maturity.  Journal of Agricultural and Food Chemistry 48: 140-146.

Wang, S.Y., Bunce, J.A. and Maas, J.L.  2003.  Elevated carbon dioxide increases contents of antioxidant compounds in field-grown strawberries.  Journal of Agricultural and Food Chemistry 51: 4315-4320.

Wentworth Jr., P., Nieva, J., Takeuchi, C., Glave, R., Wentworth, A.D., Dilley, R.B., DeLaria, G.A., Saven, A., Babior, B.M., Janda, K.D., Eschenmoser, A. and Lerner, R.A.  2003.  Evidence for ozone formation in human atherosclerotic arteries.  Science 302: 1053-1056.