What Are the Most Common Nutritional Deficiencies? (And How to Fix Them)

The human body requires many different nutrients to thrive. Some nutrients can be manufactured in the body from other sources — others are considered essential because it must be obtained from the diet.

Here, we’ll cover 6 of the most common nutritional deficiencies people living in the developed world face. 

We’ll also cover some simple foods and nutritional supplements you can use to mitigate or avoid nutritional deficiencies. 

1. Vitamin D Deficiency

Vitamin D acts more like a hormone than a vitamin. While we can obtain some vitamin D from the diet, most of this important vitamin is produced in the skin. 

UV light from the sun hits our skin and catalyses a reaction that converts cholesterol into vitamin D3. This hormone is then used to regulate calcium levels in the blood. 

Vitamin D deficiencies are prevalent in Northern climates. Three main factors cause this: 

  1. The days are short throughout the fall and winter months
  2. The cooler weather forces us to cover the skin with clothing
  3. We spend more time indoors out of the sunlight in the cooler months

Deficiencies in vitamin D are most pronounced in people with darker skin. The higher melanin content of dark skin types further blocks the UV light from reaching the skin cells where vitamin D is produced. 

Vitamin D deficiency is very common — affecting roughly 25% of people living in the UK. In the winter this number shoots up to nearly 40%. The further north of the equator you live, the higher your chances of experiencing vitamin D deficiencies. Studies have shown the average prevalence of vitamin D deficiency in the winter months in all of Europe is about 66%. 

The best way to manage or avoid low vitamin D levels is to take a vitamin D supplement — especially during the fall, winter, and early spring months. 

Signs & Symptoms of Vitamin D Deficiency

  • Muscle weakness
  • Depression (seasonal affective disorder)
  • Bone pain
  • Fatigue & lethargy
  • Cramps or muscle spasms

What to do for Vitamin D Deficiency

Vitamin D is hard to get from the diet. It’s primarily found in dairy and seafood, but the best source by far is our own skin. In the winter, it’s difficult to get enough sun exposure to meet the demand for vitamin D

Therefore, the best way to avoid and manage vitamin D deficiency is to use a quality vitamin D supplement. 

The best vitamin D supplements are made from vitamin D3 and contain added vitamin K. 

2. Magnesium Deficiency

Magnesium is one of the most versatile minerals in the body. It’s involved in well over 300 separate enzyme reactions ranging from hormone production to energy metabolism. 

It’s used to regulate neurotransmitter production, calcium absorption, and makes up a key component of our bone matrix. 

Nearly half the population is believed to be magnesium deficient — which can lead to heart arrhythmias, high blood pressure, anxiety, insomnia, and more. 

Signs & Symptoms of Magnesium Deficiency

  • High blood pressure
  • Hormone deficiencies
  • Muscle cramping
  • Poor fertility
  • Anxiety and insomnia
  • Migraine headaches
  • Restless leg syndrome
  • Insulin resistance
  • Osteoporosis

What to do for Magnesium Deficiency

The best way to avoid or manage magnesium deficiencies is to use a magnesium supplement, and include magnesium-rich foods in the diet. This includes lots of dark, leafy green vegetables, nuts, whole grains, and dark chocolate (milk chocolate doesn’t count). 

3. Omega-3 Fatty Acid

There are two main types of essential fatty acids — omega-3 and omega-6. These fatty acids are considered essential because our bodies lack the ability to manufacture these compounds ourselves. We need to obtain them from the diet. 

Both omega fatty acids are used to produce eicosanoids — which are chemical messengers tasked with regulating everything from cell reproduction to inflammation. Omega fatty acids are also used to manufacture the important phospholipid bilayer of our cell membranes. 

We need both of these EFAs for different applications. Omega-6 is more involved with pro-inflammatory processes, while omega-3 is used for reversing inflammation. 

The ideal ratio of omega-6 to omega-3 is around 4:1. 

Today, the ratio of these important nutrients are completely skewed in the modern diet. The standard Western diet is rich in omega-6 foods, and poor in omega-3. The estimated ratio in the average diet today is closer to 16:1. 

Omega-3 deficiencies have been linked with a wide range of health conditions related to inflammation — including heart disease, inflammatory bowel disease, arthritis, Alzheimer’s disease, diabetes, and much more. 

Foods High In Omega-3 Fatty Acids

  • Fish (especially mackerel, salmon, cod, herring)
  • Oysters
  • Flax seeds
  • Walnut seeds
  • Chia seeds
  • Sea kelp & algae

What to do for Omega-3 Fatty Acid Deficiency

You can get plenty of omega-3 from the diet by eating foods high in seeds, fish, and nuts. You can also get high doses of omega-3 fatty acids by taking fish oils, krill oils, or green-lipped mussel extracts. 

Copper deficiencies are not as common as other nutritional deficiencies, but the rates are increasing every year. 

Deficiencies are most common in people with poor digestive health. Inflammatory conditions such as Celiac disease, Crohn’s disease, or diverticulitis can reduce the absorption rate of copper supplements in the gut. 

Overuse of zinc supplements can also lead to copper deficiencies. Zinc and copper are absorbed through the same pathway in the digestive tract, so high zinc intake can interfere with the absorption of copper.

This deficiency is often misdiagnosed with other nutritional deficiencies or medical conditions, so it’s unclear how prevalent this deficiency truly is. 

Copper is needed for bone, heart, and immune health. It’s also necessary for the production of red blood cells. Deficiencies in this nutrient can lead to anaemia and mimic the symptoms of both iron and vitamin B12 deficiency. 

Causes of copper deficiency include: 

  • Lack of whole foods and vegetables in the diet
  • Gastric bypass surgery (reduces the ability to absorb copper)
  • Overuse of zinc supplements
  • Celiac disease or other inflammatory bowel disorders

What to do for Copper Deficiency

Eating copper-rich foods is the easiest way to avoid copper deficiency. We only need small amounts of this mineral on a daily basis (1100 mcg for women, 1400 mcg for men).

Foods high in copper include shellfish, whole grains, beans, nuts, potato, organ meats, dark leafy greens, cocoa, and yeast. 

It’s also important to consider whether your zinc supplements may be a cause for your copper deficiencies. It can help to take your zinc supplements at least an hour away from meals to avoid interfering with copper absorption in the digestive tract. 

5. Iron Deficiency


According to the World Health Organization (WHO), nearly 30% of the world are anaemic (nearly 2 billion people) — making iron-deficiencies the most common nutritional deficiency in the world. 

Iron deficiency is also one of the only nutritional deficiencies that affect the developed world nearly as much as in developing countries. 

This deficiency is most common in school-aged children, young pregnant women, menstruating women, and vegetarians.

The body needs iron to build blood cells. It forms the heme portion of the blood cells, which allows blood cells to carry oxygen and carbon dioxide around the body. As a result, iron deficiencies lead to low blood cell production (anaemia). With less red blood cells to transport oxygen around the body, iron deficiencies can lead to fatigue, dizziness, and muscle weakness. 

There are two different types of dietary iron: 

  1. Heme Iron — this is the type of iron that comes from blood cells. Most heme iron comes from meat. This type of iron has a high absorption rate. 
  2. Non-Heme Iron — This type of iron is found in both plant and animal sources, and makes up the majority of our dietary iron intake. This type of iron has a low absorption rate. 

Signs of Iron Deficiency

  • Anaemia
  • Tiredness
  • Weakness
  • Lowered Immunity
  • Pale Skin

What to do for Iron Deficiency

The best source of iron is from the diet in the form of meats. There are plant-based sources of iron as well, such as dark leafy greens and nuts, but this form of iron (non-heme iron) has a much lower absorption rate in the digestive tract. 

Iron supplements are a simple and effective way to manage iron deficiencies, especially in people who are most at risk — such as women and vegans. 

6. Iodine Deficiency

Iodine is an essential component of thyroid hormones. These hormones are produced by the thyroid gland and used to regulate metabolism, brain development, bone health, and more. 

Some estimates suggest nearly 30% of the global population experience at least some form of iodine deficiency. 

Deficiencies in this element can lead to the formation of a goitre — which is an enlarged thyroid gland, forming a large bump on the neck. Less thyroid hormone production can lead to symptoms, including fatigue, shortness of breath, lethargy, and increased weight gain. 

Signs & Symptoms of Iodine Deficiency

  • Goitre formation
  • Low-energy and fatigue
  • Weight gain
  • Lethargy
  • Poor focus and concentration

What to do for Iodine Deficiency

Iodine deficiencies can be avoided by ensuring you’re getting enough iodine in your diet. Cooking with iodised salt, or eating foods rich in iodine such as seaweed, fish (especially saltwater fish like cod and tuna), dairy (yoghurt, milk, cheese), and eggs. 

There Are also excellent supplements you can use to increase iodine consumption, such as kelp or iodine supplements. A medicinal herb, known as bladderwrack is a popular option professional nutritionists use to boost iodine intake in the diet. 

Key Takeaways: Common Nutritional Supplements, And What To Do About Them 

We can experience deficiencies in any nutrient in the human body. Severe deficiencies are much more common in developing countries where access to certain food groups is lacking. 

In the developed world deficiencies are less common, due to the abundance, and diversity of the foods we have available to us. 

Despite our access to food, certain nutrient deficiencies are unfortunately still very common.

By far, the best way to avoid nutrient deficiencies is to eat a well-balanced diet, rich in fruits, vegetables, animal proteins, and fish. Health supplements are also an excellent way to manage nutrient deficiencies or avoid them if you’re more at risk.