We live busy lives,

and it’s easy to put symptoms like tiredness, low mood, or skin problems down to stress or just “getting older.” But sometimes the answer is simpler than you’d think. B vitamin deficiencies are more common than most people realise, and the symptoms they cause can affect everything from your energy and mood to your memory and heart health.

Here’s what to look out for with each one.

B1 (Thiamine) Deficiency

A lack of B1 can lead to a condition called Beriberi, which affects the cardiovascular and nervous systems. Symptoms include weakness, nerve damage, difficulty walking, loss of sensation in the hands and feet, and in serious cases, paralysis of the lower legs.

There’s also a more severe neurological condition linked to B1 deficiency called Wernicke-Korsakoff Syndrome, which is most commonly associated with chronic alcohol use. It involves acute confusion and coordination problems, which can progress to long-term memory difficulties if not addressed.

Heavy or regular alcohol consumption is one of the most common reasons for B1 depletion. If you missed our last post on the habits that drain your B vitamins, it’s worth a read: Is Sugar Secretly Stealing Your Nutrients?

B2 (Riboflavin) Deficiency

Low riboflavin can cause a condition called Ariboflavinosis, with symptoms including a sore throat, cracked lips, inflammation at the corners of the mouth, and a swollen tongue. It can also contribute to fatigue and may increase the risk of chronic conditions like cardiovascular disease due to its role in antioxidant defence.

Interestingly, riboflavin has also been studied for its role in reducing migraines. Some researchers believe migraines may be partly caused by problems in the mitochondria, and riboflavin supports mitochondrial function, potentially helping to prevent them.

B3 (Niacin) Deficiency

A significant deficiency in B3 can lead to Pellagra, a condition remembered by its three Ds: Dermatitis, Diarrhoea, and Dementia. It can also cause skin lesions and cognitive impairments. While Pellagra is rare in the developed world today, milder B3 deficiency can still affect energy levels, skin health, and cholesterol balance.

B6 (Pyridoxine) Deficiency

B6 plays a central role in producing serotonin and dopamine, the neurotransmitters that regulate mood. A deficiency can therefore contribute to depression, mood disturbances, confusion, and in more severe cases, seizures.

It also affects immune function and haemoglobin production, meaning low B6 can leave you more susceptible to infections and contribute to a type of anaemia. Perhaps most importantly for long-term health, low B6 raises levels of a compound called homocysteine in the blood, which is linked to an increased risk of heart disease and stroke.

B7 (Biotin) Deficiency

While relatively rare, biotin deficiency can cause skin rashes, hair thinning, and brittle nails. It’s one of the more well-known B vitamins thanks to its association with hair and nail health, though true deficiency is uncommon in people eating a varied diet.

B9 (Folate) Deficiency

Low folate is one of the most clinically significant B vitamin deficiencies. It can lead to megaloblastic anaemia, where the body produces abnormally large red blood cells that don’t function properly, causing fatigue, weakness, and breathlessness.

Folate is also absolutely essential during pregnancy. A deficiency significantly increases the risk of serious neural tube defects in the developing baby, including anencephaly and spina bifida. This is why folate is a core ingredient in prenatal vitamins, and why the recommended intake increases during pregnancy.

B12 (Methylcobalamin) Deficiency

B12 deficiency is one of the most common, particularly in vegans, vegetarians, and older adults. Because B12 is found almost exclusively in animal products, those who avoid them are at significantly higher risk.

Symptoms can include pernicious anaemia, peripheral neuropathy (tingling or numbness in the hands and feet), memory problems, and cognitive decline. Studies have linked low levels of B12, along with B6 and Folate, to a higher risk of dementia. One large analysis of 95 studies found that B vitamin supplementation was associated with reduced cognitive decline.

The Heart Connection

Across B6, B9, and B12 there’s a particularly important shared role: reducing homocysteine levels in the blood. Homocysteine is a natural byproduct of protein breakdown, but when levels rise too high, it can damage blood vessel walls and increase the risk of blood clots, heart disease, and stroke. Keeping these three B vitamins topped up is one of the most straightforward ways to support long-term cardiovascular health.

What to Do If You’re Concerned

A balanced diet rich in whole grains, meat, fish, eggs, legumes, seeds, nuts, and dark leafy vegetables will cover most bases for most people. But if you recognise several of the symptoms above, or if you follow a restrictive diet, drink regularly, take certain medications, or have a digestive condition, it may be worth looking into your levels more closely.

As we explored in What Are B Vitamins and Why Do You Need Them Every Day?, these nutrients are water-soluble and not stored in the body, so regular intake really does matter.