Nutrition is the scientific study of food and how they affect the body and influence health. As bricks are to a building, so is food to our body. Without proper diet, our body will fail to remain in balance, leading to sickness, disease and death. A study of nutrition requires a thorough understanding of the essential nutrients in the diet. I will be discussing these throughout this spring semester. You will learn what they are, their function, and how they are metabolized. The six key essential nutrients are proteins, carbohydrates, lipids, water, vitamins and minerals. Proteins, carbohydrates, lipids and water are referred to as macronutrients since they are needed in large quantities, while vitamins and minerals are called micronutrients as they are needed in very small quantities. The fact that vitamins and minerals are needed only in small quantities does not mean however that they are less important. They participate in many biochemical reactions needed to keep us alive and well. If you don’t get enough of them you are likely to suffer from a nutrient deficiency disease. For example, lack of calcium may cause osteoporosis; a bone disease that makes the bone porous and weak.  

The 6 essential nutrients

Vitamins are sub-classified into fat soluble vitamins and water soluble vitamins

Minerals are sub-classified into macrominerals and microminerals depending on how much is needed in the body to maintain health. Obviously you will need more macrominerals compared to microminerals. Microminerals are needed only in trace amounts.  

Of the six essential nutrients, only proteins, carbohydrates and lipids provide us with energy; which we refer to in nutrition as kilocalories (normal people just say calories). Carbohydrates and proteins provide us with 4 kilocalories per gram while lipids (fats and oils), and alcohol provide us with 9 and 7 kilocalories per respectively. We will learn a lot more about the function of macronutrients later, but the basic functions are summarized below.

There is no question that nutrients are important. Perhaps the harder question is, “How do I know if I am getting enough or too much?”. Nutrition Professionals answer this question using six reference values. These are called the Dietary Reference Intake (DRI) valuesThey are issued by the Health and Medicine Division of the National Academy of Sciences, Engineering, and Medicine (Formerly Institute of Medicine). Here they are: 

  1. Estimate Average Requirement (EAR): The average daily intake of the nutrient needed to meet the needs of only half of any given population. The other half will need more to meet their needs. The EAR is used to calculate the RDA. If there is no EAR, there is no RDA. 
  2. Recommended Dietary Allowance (RDA): The average daily intake needed to meet the needs of almost everyone (98%) in a given population
  3. Adequate Intake (AI): The amount of nutrients that is assumed to be enough when the EAR, and RDA cannot be determined  
  4. Tolerable Upper Intake Level (UL): The average amount of nutrients, if exceeded in a day, is likely to result in health risk
  5. The Acceptable Macronutrient Distribution Range (AMDR): The average proportion of macronutrients to be consumed daily as a percentage of total calories 
  6. The Estimated Energy Requirement (EER): The average daily intake of calories needed by a population of adults based on age, gender, weight, height, and level of physical activity

The Average Macronutrient Distribution Range (AMDR)

I hope that as you go through this nutrition course, you will not just learn important facts but that it will transform your health.

Reference: Thompson,&  J., Manore, M., Vaughan, L. (2020). The science of nutrition (5th ed.). New York. Pearson

Courtney Simons
Courtney Simons is a food science professor. He holds a BS degree in food science and a Ph.D. in cereal science from North Dakota State University.
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