Feeling anxious or low? These common vitamin deficiencies could be the hidden reason

There are days when stress feels like it came out of nowhere. Sleep was decent, work wasn’t overwhelming, yet the mood dips. It is easy to blame the pace of modern life, but the story is often more layered. What sits on the plate every day can quietly shape how the brain feels and functions.

Doctors are increasingly seeing a pattern: people struggling with anxiety, irritability, or low mood, only to later discover gaps in essential nutrients. The brain, after all, is not just emotional, it is chemical. And those chemicals depend on vitamins and minerals to stay in balance.

As Medanta specialist Dr Saurabh Mehrotra explains, “While stress, anxiety, and mood changes are typically blamed on busy lifestyles, lack of sleep, or emotional stressors, nutritional deficiencies are also known to be possible contributing causes in some cases. I always tell my patients that the brain needs vitamins and minerals in sufficient amounts to make neurotransmitters such as serotonin, dopamine, and GABA, which control mood, concentration, and emotional stability.”

Vitamin D is often linked to bone health, but its role in mental well-being is just as significant. Low levels can quietly affect mood, energy, and even motivation.

Many urban lifestyles limit sun exposure. Long hours indoors, sunscreen use, and air pollution all reduce the body’s ability to produce this vitamin naturally. Over time, this can lead to a lingering sense of fatigue or emotional dullness.

Dr Mehrotra notes, “Vitamin D is one of the deficiencies I see the most often, and it can cause low mood, fatigue, and even depression in people who don’t get enough sunlight exposure.”

Government-backed research supports this link. The National Institutes of Health has published findings showing associations between low Vitamin D levels and depressive symptoms.

Vitamin B12 deficiency does not always show up dramatically. It creeps in slowly, through tiredness, brain fog, and a subtle drop in emotional resilience.

This deficiency is more common in vegetarians, older adults, and people with digestive issues. Since B12 is crucial for nerve health and brain signalling, even mild shortages can affect concentration and mood.

Dr Mehrotra explains, “They can suffer from tiredness, lack of clarity in thought processes, difficulty concentrating, anxiety, or low mood because of this deficiency.”

India has seen a growing concern around B12 deficiency, especially in plant-based diets.

Vitamin B6 and folate (Vitamin B9) rarely make headlines, but they are deeply involved in how the brain produces mood-related chemicals.

They help in synthesising serotonin and dopamine, two neurotransmitters that shape how calm, focused, or anxious a person feels. A deficiency here does not always feel physical; it often shows up as emotional instability or unexplained irritability.

Dr Mehrotra puts it simply: “Vitamin B6 and Folate (Vitamin B9) are two other vital vitamins required by the brain to function properly.”

The NIH also notes that folate plays a key role in brain health and emotional regulation.

Magnesium does not get the attention it deserves. It plays a role in over 300 biochemical reactions in the body, including those that calm the nervous system.

When magnesium levels drop, the body can feel restless. Sleep becomes lighter, headaches may increase, and anxiety feels harder to manage.
Dr Mehrotra highlights this clearly: “A magnesium deficiency can cause restlessness, headaches, insomnia, and increased anxiety.”

In a way, magnesium acts like a natural brake for the brain’s stress response. Without enough of it, the system stays in overdrive longer than it should.

Iron deficiency is widely known for causing anaemia, but its impact goes beyond physical fatigue. Low iron levels can reduce oxygen supply to the brain, which affects focus, clarity, and emotional balance.

This is especially common in women, where monthly blood loss increases the risk. Over time, it can lead to exhaustion that feels both physical and mental.

Dr Mehrotra notes, “An iron deficiency… can be responsible for fatigue, exhaustion, loss of focus, and mood disorders.”

It is tempting to look for a single fix, a supplement, a diet tweak, a quick solution. But the truth is more complex.

Dr Mehrotra cautions, “Anxiety and stress are complex issues. They do not always occur because of a deficiency. It’s important for one to follow a balanced diet, doing physical activity, sleeping well, and managing stress.”

This balance matters. Nutrition is one piece of the puzzle, not the entire picture.

This article includes expert inputs shared with TOI Health by:

Dr Saurabh Mehrotra, Director, Neurosciences, Medanta, Gurugram.

Inputs were used to explain how certain vitamin deficiencies may contribute to stress, anxiety, and mood swings, and why consulting a doctor is important before taking supplements.