Common & Critical Vitamin Deficiencies in the Western Diet

And their consequences

In Fitness And In Health
5 min readOct 4, 2023


The typical Western diet is often criticized for being high in processed foods and lacking in nutrients.

A walk down the supermarket aisles quickly confirms this.

This inadequate diet that has become our and our kids' staple can and frequently does lead to vitamin deficiencies, even in “developed” countries.

Here are some of the most widespread and talked-about vitamin shortfalls and their possible health implications.

The Outside Vitamin

Let’s begin with an obvious one that also has the easiest fix (in most places of the world).

Vitamin D deficiency is very prevalent in Western populations, with around 42% of US adults estimated to have inadequate blood vitamin D levels.

This deficiency is primarily attributed to a lack of sufficient sun exposure.

Other risk factors include obesity, darker skin tone, living in northern latitudes, and exclusivity of indoor lifestyles.

Vitamin D is essential for maintaining bone health by regulating calcium absorption. A fact that vitamin D shares with vitamin K2 (more detail here), and a reason these two should go hand in hand.

Prolonged vitamin D deficiency can lead to soft, thin, and brittle bones.

Vitamin D has also been linked to immune function, cancer prevention, and cardiovascular health.

What Is a Deficiency?

First, we must ask ourselves, what deficiency means and how we describe it.

A nutrient deficiency occurs when someone does not get enough of a vitamin, mineral, essential fatty acid, amino acid or other essential compound in their diet.

This can happen for a few key reasons:

  • Inadequate intake — The diet lacks variety or essential nutrients. For example, someone who eats a very limited diet of processed foods could become deficient in vitamins C and D over time due to lack of fruits/veggies and fortified foods.
  • Malabsorption — Certain digestive disorders like celiac disease impede the absorption of nutrients from food.
  • Increased needs — During pregnancy, growth spurts, infection, chronic disease, etc. the body requires more nutrients. If intake does not increase to meet higher needs, deficiency can occur.
  • Medications — Some drugs like diuretics, antacids, and birth control pills can deplete levels of certain nutrients.
  • Alcohol abuse — Heavy alcohol use damages the liver and lining of the GI tract. This impairs absorption of most vitamins and is a major cause of deficiencies.

When the body does not get enough of a certain vitamin, mineral, fat, or protein for a prolonged period, it can lead to symptoms and health problems.

Mild deficiencies may have subtle effects at first.

But left untreated, they can progress and cause more overt symptoms or disorders.

Testing nutrient levels through blood work or physical exams helps diagnose deficiencies.

The “Meat-eater” Vitamin

Studies estimate that up to 20% of older adults are deficient in vitamin B12.

The absorption of vitamin B12 declines with age due to reduced gastric acid secretion.

Vegans and vegetarians also have higher rates of B12 deficiency, since natural dietary sources are limited to animal foods like meat, eggs, and dairy.

But it’s not limited to the growing non-meat-eating population at all. It’s a common issue among many, since today’s mass and indoor animal farming results in lower B12 levels in animal flesh. B12 is made by bacteria in the ground which animals need to consume through grazing and natural food outside.

Vitamin B12 plays vital roles in red blood cell formation, neurological function, methylation, and DNA synthesis.

Deficiency can lead to anemia, fatigue, elevated homocysteine levels, and neurological issues like dementia.

The Immune System Vitamin

While full-blown scurvy is rare, vitamin C deficiency still affects around 7% of the US population.

This is surprising because vitamin C is found in high amounts in countless natural foods, and it's also one of the most supplemented vitamins in the Western world.

Smokers have a higher risk of deficiency due to increased metabolic requirements for vitamin C.

The most common cause is simply not eating enough fresh fruits and vegetables.

Vitamin C has antioxidant properties and is needed for collagen production, immune function, iron absorption, and tissue repair.

Early signs of vitamin C deficiency include fatigue, bleeding gums, and corkscrew hairs.

The Blindness Vitamin

This vitamin deficiency has well-known and serious consequences.

Vitamin A deficiency is uncommon in the US but higher in developing countries.

Groups at increased risk include the elderly, alcoholics, and those with fat malabsorption conditions.

Vitamin A supports immune system function, vision, gene expression, and reproductive health.

Deficiency can lead to blindness, frequent infection, and xerophthalmia (dry eyes).

Vitamin B6

While overt vitamin B6 deficiency is rare, some studies indicate around 20% of the population has insufficient blood levels of this important B vitamin.

Risk factors for B6 deficiency include aging, alcoholism, impaired kidney function, and medications like oral contraceptives.

Vitamin B6 plays cofactor roles in over 100 enzyme reactions. It’s essential for amino acid metabolism, glucose generation, immune function, and hemoglobin formation.

Prolonged deficiency of B6 can result in peripheral neuropathy, dermatitis, confusion, and weakened immunity.

The Pregnancy Vitamin

Folate, also known as vitamin B9, is a commonly mentioned and crucial vitamin for pregnant women. But we all require adequate folate intake.

Thanks to the introduction of folic acid in fortified foods, folate deficiency has declined dramatically in the last few decades.

However, alcoholics and the elderly have an increased risk of inadequate folate intake and stores.

Folate is vital for nucleotide and amino acid biosynthesis. It also supports cardiovascular health by lowering homocysteine.

Inadequate folate during early pregnancy significantly increases the risk of neural tube defects.

Anemia, headaches, and fatigue are symptoms of deficiency.

The Nerve Vitamin

While vitamin E deficiency is not common, most adults fail to meet the recommended intakes from diet alone.

Certain fat malabsorption disorders can increase the risk of deficiency.

Vitamin E functions as an antioxidant to prevent free radical damage to cells. It also supports the immune system.

Vitamin E deficiency impairs nerve conduction, weakens the immune system, and may raise heart disease risk.

The Bottom Line

While nutrient deficiencies are more prevalent in developing countries, shortfalls in vitamins like D, B6/12/9, C, E, and A are still possible or even common in Western populations.

These deficiencies can negatively impact long-term health.

The keyword is long-term here!

Consuming a balanced diet high in a variety of vegetables, fruits, whole grains, beans, lentils, nuts, seeds, grass or naturally-fed meat, wild-caught fish, and omega-3 fats will help provide optimal vitamin intakes and prevent most deficiencies.

However, certain medical conditions, inappropriate lifestyle, high intake of alcohol and nicotine, and other substances can negatively impact vitamin deficiencies, even in “healthy-eating” individuals.

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