Few things to know:

Complex Carbohydrates vs Simple Carbohydrates

Carbohydrates are good sources of energy and essentials nutrients, and can be found in the following:
dairy products
fruits
vegetables
grains
nuts
legumes
seeds
potatoes
plantain
Yucca/Cassava
Yam
Cocoyam
sugar
sweets

Carbohydrates are made of 3 components: fiber, starch, and sugar. Fiber and starch are complex carbs, and sugar is a simple carb. 

Complex Carbohydrates 

rice 
pasta 
potato
Beans
Bread
cereals
milk and yogurt(essential source of vitamin B12) 

Simple Carbohydrates 

Milk
fruits
vegetables
sugar
honey

The difference between complex and simple carbohydrates is in how quickly each of them is digested and absorbed in our mainstream- and how their chemical structures are formed. 

Complex carbohydrates are bounded by longer saccharides chains, thus taking much longer to break down and keeping our stomach fuller. 
Simple carbohydrates( also called sugars including the natural sugar found in milk, fruits, and vegetables) on the other hand can break down more quickly because they are only bounded by one molecule. 
Vitamin B12 (as mentioned earlier) deficiency is related to neurological and cognitive disorders, stunted growth, congenital malformations, and anemia.

Grains, Beans, Nuts, and seeds

Grains- seeds of grass: e.g. rice, corn, oats, wheat

Beans- seeds of legumes: e.g. lentils, soybeans, peas, chickpeas

Nuts- seeds of trees: e.g. hazelnuts, pecans, walnuts

Seeds: e.g. poppy seeds, sunflower

 Beans are full of fiber; high in antioxidants; provide complete proteins when eaten with bread; rich in iron, copper, magnesium, and zinc. 
Nuts provide a generous supply of fiber, vitamins, minerals, and good fats(monounsaturated fats).
Grains also include fiber, vitamins B( niacin, thiamin, riboflavin, and folate), and of course minerals. 
Seeds are rich in fiber, and monounsaturated fats( very essential in lowering the bad cholesterol while enhancing your heart functioning). Seeds are equally loaded with vitamins, proteins, and minerals.

Soluble fiber vs Insoluble fiber 

They both facilitate digestion, absorption of nutrients, prevention of diseases, and weight loss. 
Insoluble fiber speeds food through the digestive system and prevents constipation. It doesn't dissolve in water. 
Soluble fiber attracts water and becomes gel in the intestine. It also contributes to stabilize blood sugar which slows the absorption of glucose into the blood- which in return reduce the likelihood of certain conditions like diabetes). 

Health benefits of insoluble fiber include 
weight loss by helping stay off hunger for a longer period of time; 
improving the digestive system by reducing constipation and bowel related issues-and hemorrhoids.

Health benefits of soluble fiber also include the protection of heart. Soluble fiber binds to cholesterol parts and removes them from our bodies /- thus reducing the level of cholesterol in our system and risks related to cardiopathies. Soluble fiber allows a slower absorption of glucose into the blood, which in turn balances the sugar level so that it doesn't rise too drastically. 

  
  

    




http://www.diagnosisdiet.com/food/grains-beans-nuts-and-seeds/

http://www.nutrientsreview.com/carbs/dietary-fiber-soluble-insoluble.html
https://nutritionfacts.org/2015/05/26/how-phytates-fight-cancer-cells/  http://www.yogurtinnutrition.com/milk-and-yogurt-may-increase-vitamin-b12-intake/