How Nutrient Deficiencies Deplete Energy Levels

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Written by  Maxine Fidler, ND, MS 

There are many causes for fatigue, from lack of sleep to elevated stress levels. Dietary deficiencies may also cause tiredness. Unfortunately, a healthy diet is often one of the first things to go when we are stressed and overworked. Let’s talk about why nutrient consumption is more important than ever!

Iron is required for the formation of hemoglobin, which the red blood cells use to carry oxygen. Iron deficiency can cause fatigue. If there is not enough iron, there is not enough hemoglobin, resulting in less oxygen to power the muscles and brain. Dietary iron can be found in animal sources (meat, fish, and poultry) and plant sources (raisins, prunes, beans, tofu, and leafy greens).[1] The animal sources contain heme iron, and the plant sources contain non-heme iron. While heme iron is more easily absorbed, absorption of non-heme iron can be increased by consuming it with citrus foods and away from dairy products. Food sources of non-heme iron also often contains phytate, which inhibits iron absorption. The impact of phytate can be minimized by soaking grains and legumes before cooking.

B12 deficiency can also cause fatigue. Vitamin B12 is vital for healthy red blood cells, though in a different way than iron. As with iron, B12 deficiency can cause fatigue due to less oxygen powering the muscles and brain. Vitamin B12 can be found in meat, poultry and fish, as well as dairy and eggs.[2] Vegan sources of B12 include nutritional yeast and fortified foods.

Magnesium deficiency is a lesser-known cause of fatigue, but it makes sense when we think about its actions in the body. One of the functions of magnesium is to enable cells to make and store ATP. If we don’t have enough magnesium, cellular energy production decreases, causing fatigue.[3] Foods high in magnesium include nuts, brown rice, and leafy greens.[4]

While extreme vitamin C deficiency is known to cause scurvy, it is less well known that mild to moderate deficiency can cause fatigue.[5] Vitamin C is a cofactor in the synthesis of carnitine, which is needed to transport fatty acids into the mitochondria where it helps with energy production.[6] Because of this, vitamin C deficiency can result in carnitine deficiency, which results in decreased energy production, leading to fatigue. Vitamin C can be found in kiwi, citrus fruit, strawberries, bell pepper, broccoli, and others.[7]

Eating a healthy, varied diet[8] and addressing nutrient deficiencies may help reduce fatigue and support optimal energy levels. Nutrient deficiency is optional. Nutrient supplementation, including a good multivitamin and mineral supplement can help in this. Next time we’re tired, let’s feed our cells instead of reaching for coffee.


  1. Linus Pauling Institute. Iron. 2020. Accessed December 13, 2020.
  2. Linus Pauling Institute. Vitamin B12. 2020. Accessed December 13, 2020.
  3. Tardy AL, Pouteau E, Marquez D, et al. Vitamins and minerals for energy, fatigue and cognition: A narrative review of the biochemical and clinical evidence. Nutrients. 2020; 12(1):228.
  4. Linus Pauling Institute. Magnesium. 2020. Accessed December 13, 2020.
  5. Linus Pauling Institute. Vitamin C. 2020. Accessed December 13, 2020.
  6. Adeva-Andany MM, Calvo-Castro I, Fernández-Fernández C, et al. Significance of l-carnitine for human health. IUBMB Life. 2017; 69(8):578-94.
  7. Linus Pauling Institute. Vitamin C. 2020. Accessed December 13, 2020.
  8. Canada’s Food Guide. 2020. Accessed December 13, 2020.
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