Vegetables are rich in nutrients and help prevent diseases such as cancer, cardiovascular and cerebrovascular diseases, diabetes, and osteoporosis. However, if some vegetables are not prepared properly, not only can you not obtain their nutritional benefits, but they may also be detrimental to your health. The following categories are the most easily overlooked.
Fennel, celery, and crown daisy have high sodium content, so use less salt when cooking. According to the Chinese Food Composition Table, every 100 grams of fennel contains 186.3 mg of sodium, equivalent to 0.47 grams of salt per 100 grams. Crown daisy has a sodium content of 161.3 mg/100g, celery stalk has 159 mg/100g, while winter melon has only 1.8 mg of sodium per 100g. Therefore, when cooking fennel, celery, and crown daisy, you should use less or no salt at all, especially for patients with hypertension and kidney disease. Vegetables like various radishes, Chinese cabbage, bok choy, cabbage, rapeseed, and spinach have a sodium content of 40-100 mg/100g, which is considered medium-to-high sodium; salt can be moderately reduced when cooking them. Lettuce, romaine lettuce, cauliflower, broccoli, amaranth, and asparagus have a sodium content of 10-40 mg/100g, which is low sodium. Various beans and gourds have a sodium content below 10 mg/100g, which is extremely low sodium. For the last two categories, salt can be used normally during cooking.
Lentils, asparagus, seaweed, and pea shoots have high purine content and should be eaten less during an acute gout attack. Many people believe that vegetables have low purine content and do not trigger gout, so there is no need to restrict them. Compared to animal foods like animal offal, seafood, and meat broth, the purine content in vegetables is generally lower. However, foods like lentils, asparagus, seaweed, and pea shoots have relatively high purine levels, and patients should avoid them during an acute gout attack, reducing frequency and amount during the remission period. Vegetables that gout patients almost need not worry about include light-colored leafy vegetables like Chinese cabbage, cabbage, and baby bok choy; root and stem vegetables like potatoes, taro, sweet potatoes, and radishes; solanaceous fruits like tomatoes, eggplants, and bell peppers; and gourds like winter melon, loofah, cucumber, and pumpkin.
Lotus root, water chestnut, water caltrop, arrowhead, and Chinese yam have high starch content, so their consumption should reduce the amount of staple foods. Most vegetables are low in calories, but some like lotus root, water chestnut, water caltrop, arrowhead, and various tubers (potatoes, sweet potatoes, Chinese yam, taro) have high starch content. If you eat large amounts of these vegetables without reducing your staple food intake, it will increase calorie consumption and ultimately lead to obesity. The correct approach is to replace some rice and flour staple foods with high-starch vegetables, as they have higher dietary fiber and vitamin content, a lower glycemic response, and stronger satiety, making you less likely to feel hungry for the same calorie intake. In contrast, vegetables like tomatoes, cucumbers, winter melon, zucchini, cabbage, radishes, lettuce, and cabbage have high water content and low calories, and can be eaten almost without restriction.
Amaranth and spinach have high oxalic acid content, while wild vegetables like purslane and shepherd's purse have a high risk of contamination, and toon shoots have high nitrate and nitrite content. Blanch them before cooking. Excessive intake of oxalic acid can affect the absorption of minerals like calcium and zinc in the body and increase the risk of kidney stones. Generally, vegetables with a slightly astringent taste, such as spinach, amaranth, and water bamboo, contain more oxalic acid. Wild vegetables like purslane and shepherd's purse grow in fields and may carry risks of pesticide residues or contamination from wastewater and exhaust gases. Toon shoots contain high levels of nitrates and nitrites (converted from nitrates during storage), posing a certain carcinogenic risk. Blanching these three types of vegetables before cooking helps remove the components that are harmful to health. Research has shown that for vegetables like spinach and amaranth, blanching in boiling water for a short time can remove 40% to 70% of the oxalic acid.