Sardine
Sardines are a popular food in many countries as they are loaded with many essential nutrients, such as omega-3 fatty acids, minerals, and protein. More importantly,100 grams of sardines contain around 175 IU or 22 percent of the daily recommended intake. Unlike other fish, sardines basically eat plankton. This means they do not carry toxins and heavy metals, making them one of the cleanest sources of vitamin D. You can purchase sardines in a can or fresh without affecting nutrient contents. [3]