Extended Data Table E1.

Percent change in nutrient content at elevated [CO₂] relative to ambient [CO₂]

	N* (number of pairs)	Zn (μg/g)			Fe (μg/g)			Protein (mg/g)			Phytate (g/100g)
		%	95% CI	P-value	%	95% CI	P-value	%	95% CI	P-value	%	95% CI	P-value
C3 grasses
Wheat	64	−9.3	(−12.7, −5.9)	<.0001	−5.1	(−6.5, −3.7)	<.0001	−6.3	(−7.5, −5.2)	<.0001	−4.2	(−7.5, −0.8)	0.009
Rice	31	−3.3	(−5.0, −1.7)	<.0001	−5.2	(−7.6, −2.9)	<.0001	−7.8	(−8.9, −6.8)	<.0001	1.2	(−4.6,7.4)	0.697
C3 legumes
Field peas	10	−6.8	(−9.8, −3.8)	0.002	−4.1	(−6.7, −1.4)	0.003	−2.1	(−4.0, −0.1)	0.039	−5.8	(−11.5,0.1)	0.055
Soybeans	25	−5.1	(−6.4, −3.9)	<.0001	−4.1	(−5.8, −2.5)	<.0001	0.5	(−0.4,1.3)	0.267	−1.3	(−3.7,1.2)	0.303
C4 grasses
Maize	4	−5.2	(−10.7,0.6)	0.077	−5.8	(−10.9, −0.3)	0.038	−4.6	(−13.0,4.5)	0.312	−6.1	(−15.0,3.7)	0.215
Sorghum	4	−1.3	(−6.2,3.8)	0.603	1.6	(−5.8,9.7)	0.674	0.0	(−4.9,5.2)	0.993	12.8	(−15.8,51.1)	0.418

^*number of pairs refers to the number of comparisons where replicates of a particular cultivar grown at a specific site under one set of growing conditions in one year at elevated [CO₂] have been pooled and mean nutrient values for these replicates are compared with mean values for identical cultivars under identical growing conditions except grown at ambient [CO₂]. In most instances, data from four replicates were pooled for each value meaning that eight experiments were combined for each comparison (see Table 1 for details of experiments).