Whole grains are high in dietary fiber (6 trusted sources).
They consist of three main parts (7 trusted sources, 8 trusted sources):
- Bran: The hard outer layer contains fiber, minerals and antioxidants.
- Germ: A nutrient-rich core that contains carbohydrates, fats, proteins , vitamins, minerals, antioxidants and plant compounds.
- Endosperm: the middle layer, which mainly contains carbohydrates and a small amount of protein.
Bran and germ are the most nutritious parts of whole grains .
They contain large amounts of many nutrients, such as fiber, vitamin B, iron, magnesium, phosphorus, manganese and selenium.
In the refining process, the bran and germ and all the nutrients they contain are removed (9 trusted sources).
This leaves almost no fiber, vitamins or minerals in the refined grains. The only thing left is fast-digested starch and a small amount of protein.
That being said, some manufacturers add synthetic vitamins to their products to compensate for the loss of certain nutrients.
For a long time, whether synthetic vitamins are as good as natural vitamins. However, most people will agree that getting nutrients from whole foods is always the best option (10 trusted sources).
High-refined carbohydrate diets also tend to have lower fiber content. A low-fiber diet is associated with an increased risk of diseases such as heart disease, obesity, type 2 diabetes, colon cancer, and various digestive diseases (11 trusted sources, 12 trusted sources, 13 trusted sources).