Bananas aren't the highest in magnesium, and tomatoes aren't necessarily the top source of vitamin C—don't "pigeonhole" food nutrition.
At some point, people started developing a "pigeonholed" view of nutrients in food. When certain nutrients are mentioned, they immediately bring a specific food to mind. For instance, mention vitamin C, and people instantly think of tomatoes; mention potassium, and they think of bananas; mention carotene, and carrots are a sure bet; mention spinach, and oxalic acid comes to mind; mention celery, and the thought is of lowering blood pressure... In reality, the health benefits of food shouldn't be "pigeonholed." Take a look at the examples of the nutritional value of the following foods, and you'll understand:
Bananas are not the "champion" of magnesium
Taro contains about 50% more potassium than bananas. In fact, all tubers are excellent sources of potassium. Simply replacing a bowl of rice with potatoes of equivalent starch content can increase potassium intake tenfold. People with high urine output, such as diabetics, kidney stone patients, gout sufferers, hypertensives, and those who eat very salty foods, can easily lose potassium from their bodies. Replacing staple foods with tubers is a good idea.
Actually, among green leafy vegetables, many have a potassium content that surpasses bananas, such as spinach, kale, lettuce leaves, water spinach, amaranth, and red kale.
Magnesium is important for strong bones and controlling blood pressure, and is also hailed as an "anti-stress nutrient." However, when it comes to magnesium, people still usually think of bananas. In fact, it's only the champion of magnesium among fruits. Almost all dark green leafy vegetables are great sources of magnesium, with levels reaching or even exceeding that of bananas. The reason is simple: every chlorophyll molecule contains a magnesium ion, so the greener the color, the more magnesium it contains.
Another excellent source of magnesium is nuts and seeds; for example, eating 50 grams of watermelon seeds provides as much magnesium as 200 grams of green leafy vegetables. However, green leafy vegetables have only one-third the calories of bananas and about one-twentieth of nuts. So, if you're worried about gaining weight, green leafy vegetables are the best choice for supplementing potassium and magnesium.
Tomatoes are not the top source of vitamin C
It's commonly believed that tomatoes are the top vegetable source of vitamin C, but in fact, potatoes contain more vitamin C than tomatoes. Not only potatoes, but also sweet potatoes, taro, and Chinese yam are rich in vitamin C. The vitamin C content in various green leafy vegetables generally exceeds that of tomatoes. Bell peppers are indeed the champions of vitamin C among vegetables, but their lower acidity means vitamin C is lost more significantly during cooking. Although potatoes have only one-third the vitamin C content of bell peppers, the starch in potatoes provides strong protection for vitamin C, so the loss during steaming or boiling is minimal. Therefore, if you use potatoes as a staple food, your body's vitamin C needs can be met even without eating other vegetables or fruits. In the past, when people in the north couldn't get fresh vegetables in the winter, many did not suffer from vitamin C deficiency because they often used potatoes and sweet potatoes as their staple foods.
To understand the nutritional value of foods, never just remember a few so-called "representatives." In fact, the nutritional value of many foods is no worse than theirs; they are just less well-known. Therefore, a healthy diet doesn't have to be rigidly tied to certain foods. The most important thing is a reasonable mix of various food groups. If you don't like a particular food, you can completely substitute it with another.