Although there is no scientific definition, superfoods are nutrient dense and often versatile in the way they can be used and consumed. Superfoods are packed full of antioxidants, polyphenols, vitamins, and minerals. 
Many online sources refer to a wide range of fruits and vegetables as being superfoods. This is incorrect, and they are essentially labeling anything which is healthy as a superfood. Here we will be discussing three foods which have long been considered traditional superfoods. Let's get started.
Coconut Oil
This superfood has been vilified in the past because it
Contains high levels of saturated fat. Coconut oil is one of the richest sources of saturated fat out there with nearly 90% of its fat content being saturated fat. However, the saturated fat found in coconut oil is different of that found in other foods. The saturated fats found in coconut oil are medium chain triglycerides which are metabolized differently by the human body and have many beneficial properties. Most people hear the word fat and automatically think of something negative. Fats have had a negative connotation attached to them for a long time, but the truth is much more complicated. We need fat to be healthy and disease free. Many of the problems that arise from fats in our diet are due to overconsumption and to fats such as trans fat which can be very dangerous and should be avoided. 
Coconut oil is the only food which can be eaten, used to cook with (frying food), and applied to the skin. Truly a remarkable superfood. Its benefits include, improved digestion, reduces inflammation, increases brain function, lowers the risk of heart disease, helps build muscle, increases weight loss, helps keep hair, skin, and nails healthy, and on and on. Coconut oil also helps raise HDL levels (good cholesterol). 
Remember to stay away from hydrogenated coconut oil. In fact stay clear of all hydrogenated oils. They are unhealthy and dangerous. 
Seaweed or algae as it is also known, come in a few different varieties. Brown algae such as wakame and kelp.  Red algae such as nori (sushi seaweed). Blue-green algae such as spirulina and chlorella. Green algae such as sea lettuce and sea grapes. Seaweed is rich in calcium, folate, magnesium and iron. Different seaweed varieties contain varying levels of these nutrients. However, each type consists of nutrients which are essential to our well-being. Seaweed is also an excellent source of protein with anywhere from 20% to 70% depending on the variety. Additionally, they are a rich source of minerals. Especially, iodine, iron, calcium, and magnesium. Most seaweed varieties have a high concentration of vitamin c, more so than oranges. If all that isn't enough, seaweed contains antibacterial, antiviral, and anti-inflammatory properties. Now, that's a superfood. 
This leafy green vegetable is packed with such a multitude of nutrients that it's hard to believe there are still people out there who know nothing about it.  A 100 gram serving of kale contains 200% of the RDA (recommended daily intake) for Vitamin C, 300% of the RDA for Vitamin A, and 1000% of the RDA for Vitamin K1. It also contains significant amounts of calcium, magnesium, Vitamin B6, potassium, manganese, and copper. Kale is also a rich source of protein and fiber.  Not to mention that a 100 gram serving of kale contains only 50 calories. Kale is also a rich source of antioxidant carotenoids and flavonoids both of which have been shown to help reduce the risk of certain cancers. The goodness this leafy green vegetable provides is impressive. I would recommend taking the time to find some yummy recipes. There are a lot of ways which kale can be prepared and added to your diet. 
Superfoods are a healthy addition to any diet. Their versatility and the broad range of nutrients they offer make them a valuable commodity. I always tell my clients that when choosing which fruits and vegetables to eat you want variety. That means mainly a variety in color. The more colors you add to your diet on a regular basis the greater the diversity of nutrients you are making available to your body. Superfoods offer a broad range of nutritional diversity all by themselves. So I would highly recommend these three superfoods to people of all ages and walks of life. I also want everyone out there to be wary of con men and frauds. Not too long ago I would see advertisements for goji berries everywhere. Well-respected doctors and members of the nutritional community were making outrageous claims. These charlatans went from city to city telling people that goji berries can cure cancer as well as a litany of other diseases. People spent their life savings on goji berry products trying to prolong their lives and the lives of their loved ones. Anyone who claims that a single fruit or vegetable will cure disease is a fraud. The goji berry has been studied and analyzed. I have yet to read a single legitimate study showing it to be anything more than a regular fruit. That is not to say it doesn't have any health benefits. Those benefits, however, have been exaggerated and grossly misrepresented. Please remember to research anything that people are claiming is a magic bullet. If it sounds too good to be true, it probably is.