What is a nutrient deficiency?

A nutrient deficiency occurs when the body is not getting enough of one or more essential nutrients. These are the vitamins and minerals the body needs to function properly. While all essential nutrients can be found in food, factors like a lack of consistent access to a variety of foods, having certain dietary restrictions, or struggling with a chronic illness like cancer or celiac disease can all increase the risk of experiencing nutrient deficiencies. Conditions like celiac disease and Crohn’s Disease affect nutrient absorption as do certain prescription medications like heartburn medications.

A nutrient deficiency can be difficult to identify. Sometimes symptoms show up as fatigue or hair loss which are often blamed on life stressors, the kind that most people experience in some form on a day-to-day basis. When you’re feeling run down or experiencing brain fog, you may think you’re just not getting enough sleep or that you should take up a yoga and meditation practice for stress management. While these habits can be highly beneficial, the real culprit of your symptoms could be due to a deficiency in a nutrient like iron, iodine, or vitamin B12.

What are some common nutrient deficiencies?

Vitamin D

Vitamin D has many roles in the body. It supports bone health and immune system regulation. Vitamin D deficiency is common since it has fewer food sources than some other vitamins, although vitamin D can be found in foods like salmon, mushrooms, eggs, and fortified foods, like dairy and cereals. Our body produces vitamin D from sunlight exposure so being mindful of food sources or even supplementation during the winter months may be helpful.

Vitamin B12

Vitamin B12 is used by the body to make red blood cells, nerves, DNA, and for other functions. Found in animal-sourced foods like meat, dairy, and eggs, those following a vegan or vegetarian diet may need to supplement or consume grains like bread and rice that have been fortified with vitamin B12. The most common symptoms of B12  deficiency are general weakness, fatigue, loss of appetite, mental impairment, and loss of balance. 


Iron is necessary to support the movement of oxygen in the blood, making sure that our body is getting the oxygen it needs from our blood cells. Iron deficiency is more common in women, particularly those who are menstruating, pregnant, or breastfeeding. There are two types of iron – heme iron which is found in red meat and non-heme iron which is found in plant foods like spinach. It is more difficult for the body to absorb non-heme iron from plants so those following a vegan or vegetarian diet may need to get regular blood tests to make sure their iron levels are sufficient. Vitamin C also helps with iron absorption – this is important for those who are anemic and might have to take supplements. 


Iodine is a mineral used by the body to make thyroid hormones. Iodine is essential for making sure the thyroid is functioning properly and regulating the metabolism. The most common symptom of iodine deficiency is an enlarged thyroid gland, also called a goiter. The thyroid is a gland located in the front part of the neck and is responsible for many functions in the body. Iodine can be found in iodized table salt, seafood, seaweed, dairy products, and meat. As with other vitamin deficiencies, those following a vegan or vegetarian diet may need to be more conscious of their iodine intake, possibly taking a multivitamin with iodine or using iodized salt to prevent deficiency.


Calcium is very important for long-term bone health. As we age, our bones can start to get small holes as they lose density, a condition called osteoporosis. Sufficient intake of calcium is an important way to prevent osteoporosis. While calcium is commonly found in dairy products like milk and cheese, you can also get calcium from sardines, salmon, fortified orange juice, and green vegetables like kale and broccoli.

How does a nutrient deficiency happen?

A nutrient deficiency can happen for any number of reasons.

A nutrient deficiency can happen for any number of reasons. For those experiencing an illness or chronic condition, the body may have trouble absorbing nutrients from food so even if you are eating a balanced diet, you may have difficulty accessing the vitamins and minerals in your food for use.

It may also be a challenge eating enough servings of fruits, vegetables, whole grains, and protein to meet daily nutrient needs. This is often the case for individuals undergoing cancer treatment and other illnesses where the appetite is suppressed. The recommended intake of fruits and vegetables for adults is around 6 cups and up to 4 cups for children. Without a multivitamin or supplementation of specific nutrients, like a vitamin B complex for those not eating any animal foods, it can be easy to become deficient.

How to find out if you have a nutrient deficiency?

It’s helpful to talk to your doctor or healthcare practitioner about your diet and nutrient needs since the standard annual physical will not typically include tests for nutrient levels. If you are concerned you may not be getting enough of any nutrient from your diet, blood tests can be done to test levels of vitamin D, iron, iodine, and others. Taking a multivitamin can also be a helpful way to ensure you are getting the vitamins and minerals your body needs for optimal health, especially when you are dealing with illness or unable to eat enough of the foods needed to reach nutrient needs.

Note: It is recommended to consult your primary doctor before furthering with any supplements or dramatic lifestyle changes.

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