Table 1.
Quercetin content in commonly-eaten foods in Japan.
| Acquisition period | Food | Quercetin content |
|---|---|---|
| (mg 100 g−1 FW or mg (100 mL)−1 *) | ||
| June–July 2013 | Red leaf lettuce (Lactuca sativa L. var. crispa) | 30.6 |
| Asparagus (Asparagus officinalis L.) | 23.6 | |
| Romaine lettuce (Lactuca sativa L. var. longifolia) | 12.0 | |
| Onion (Allium cepa L.) | 11.0 | |
| Green pepper (Capscicum annuum L.) | 9.9 | |
| Asupara-na (Brassica rapa) | 4.3 | |
| Cherry tomato (Solanum lycopersicum) | 3.3 | |
| Podded pea (Pisum sativu L.) | 1.7 | |
| Tomato (Solanum lycopersicum) | 1.6 | |
| Broccoli (Brassica oleracea var. italica) | 1.6 | |
| Cherry (Prunus avium L.) | 1.2 | |
| Green tea infusion | 2.1* | |
| Welsh onion (Allium fistulosum L.) | N.D. | |
| Spinach (Spinacia oleracea L.) | N.D. | |
| Potato (Solanum tuberosum L.) | N.D. | |
| Red shiso1 (Perilla frutescent var. crispa) | N.D. | |
| Green shiso2 (Perilla frutescent var. crispa) | N.D. | |
| Eggplant (Solanum melongena L.) | N.D. | |
| Cabbage (Brassica oleracea L. var. capitata) | N.D. | |
| Dried buckwheat nudles (boiled) | N.D. | |
| December 2013 | Onion (Allium cepa L.) | 41.9 |
| Red leaf lettuce (Lactuca sativa L. var. crispa) | 10.3 | |
| Apple (Fuji) (Malus domestica Borkh.) | 2.3 | |
| Broccoli (Brassica oleracea var. italica) | 0.5 | |
| Spinach (Spinacia oleracea L.) | N.D. | |
| Garland chrysanthemum (Glebionis coronaria) | N.D. | |
| Chinese cabbage (Brassica rapa var. pekinensis) | N.D. |
N.D., not detected; FW, fresh weight. 1 Perilla frutescens var. crispa f. crispa. 2 Perilla frutescens var. crispa f. purpurea. Each food item was purchased 1–3 times and each sample was determined in triplicate. Values are expressed as mean of 1–3 samples.