It's no mystery that some foods are healthier than others. You also know that you should aim to get fruits, vegetables, whole grains and lean meats into your diet. Unfortunately, it isn't always easy to determine how much of these foods you should be consuming.

Healthy foods
Black beans, a type of legume, are high in protein and fiber. They also contain a small amount of omega-3 fatty acids to help with heart health.

As a member of the cruciferous family, kale can help fight cancer. It's also full of fiber, antioxidants and vitamin K which can help with blood clotting as well as cell growth. 

Most people know how good salmon is for you. Wild salmon is rich in vitamin D and omega-3 fatty acids. According to Time, omega-3s may also provide support in protecting against premature brain aging and memory loss. 

Although nuts are higher in calories and fat, they contain monosaturated fat which is healthier than the saturate fat found in meat and dairy products. Walnuts are ideal because they have one of the highest antioxidant content of all nuts.

Pumpkin probably doesn't come to mind other than during the holidays. However, this low-calorie vegetable has high fiber and vitamin A content. Time said the beta carotene, which makes the vegetable orange, helps prevent heart disease. 

They were right when they said an apple a day keeps the doctor away. This fruit is high in a fiber called pectin, which can help lower bad cholesterol.

Blueberries are perfect if you're looking to increase your antioxidant intake. They are high in carotenoids and flavonoids and keep your heart, memory and urinary-tract in optimal condition. 

Celery can help fight off indigestion and control blood pressure. 

Rich in the antioxidant lycopene, tomatoes can reduce your risk of stroke. Watermelon and pink or red grapefruit will do the trick, too.