Table 2.

Meta-analysis of dietary/circulatory antioxidants (highest v. lowest category analysis) and risk of total cardiovascular mortality

Antioxidant	No. of studies	RR	95 % CI	I 2 (%)	95 % CI	P heterogeneity	Meta-evidence	NutriGrade score	Explanation of the results according to recommendations of the NutriGrade scoring system
Dietary vitamin C	10	0·79	0·68, 0·89	46	0, 74	0·06	High	8·4	There is high confidence in the effect estimate, and further research probably will not change the confidence in the effect estimate
Circulating vitamin C	6	0·60	0·42, 0·78	65	15, 85	0·01	Moderate	6·4	There is moderate confidence in the effect estimate; further research could add evidence on the confidence and may change the effect estimate
Dietary vitamin E	8	0·91	0·79, 1·03	51	0, 81	0·04	Low	5·4	There is low confidence in the effect estimate; further research will provide important evidence on the confidence and likely change the effect estimate
Circulating α-tocopherol	5	0·82	0·76, 0·88	0	0, 79	0·55	Low	4·0	There is low confidence in the effect estimate; further research will provide important evidence on the confidence and likely change the effect estimate
Dietary β-carotene	4	0·89	0·73, 1·05	35	0, 77	0·21	Low	5·5	There is low confidence in the effect estimate; further research will provide important evidence on the confidence and likely change the effect estimate
Circulating β-carotene	6	0·68	0·52, 0·83	50	0, 80	0·07	Low	5·9	There is low confidence in the effect estimate; further research will provide important evidence on the confidence and likely change the effect estimate

RR, relative risk.