Rhubarb

Rhubarb is high in fiber, vitamin K, calcium, and other vitamins and minerals. It also includes prebiotic fiber, which encourages the growth of good bacteria in your stomach. Antioxidants are abundant in rhubarb, especially anthocyanins (which give it its red color) and proanthocyanidins. Anti-bacterial, anti-inflammatory, and anti-cancer properties of these antioxidants can protect you against a variety of health conditions, including heart disease, cancer, and diabetes.

Rhubarb, like spinach, is high in oxalates, which prevents most of the calcium from being absorbed. According to one research, your body can only absorb around 5% of the calcium in rhubarb. Rhubarb, on the other hand, is a calcium source even if you're only absorbing a small amount, with 105 mg of calcium per cup (122 grams) of raw rhubarb, or about 8% of the DV.