Feeling tired? How vitamin B deficiency contributes to tiredness, especially in older people.

30 September 2020

Vitamin B deficiency can affect anyone and a lack of vitamin B in the diet can contribute to feelings of fatigue and sluggishness. If your diet and lifestyle is sub-optimal, then you may well be missing some of the B vitamins which are linked to how your body makes energy.

So before you reach for a can of energy drink (which ignores possible causes of your tiredness), we explore the 8, yes eight B Vitamins and their important roles.

B vitamins (B1, B2, B3, B5, B6, B8, B9, and B12) are critical to releasing energy from the food we take in. Deficiency in any of them can cause both mental and physical fatigue.

How Vitamin B Deficiency Causes Fatigue

The B vitamins are water-soluble micronutrients which means our bodies cannot store them. We therefore need a regular intake because each B vitamin affects how our cells generate energy to fuel bodily functions.

Fatigue is a common symptom of a lack of B vitamins. It causes persistent exhaustion which in turn can lead to lethargy and a lack of motivation.

Vitamin B1 (Thiamine)
Vitamin B1 helps break down glucose to release energy. It is essential for the production of DNA, RNA, and energy-rich molecules known as ATP. The deficiency symptoms begin to appear about a month after stopping intake.

Vitamin B2 (Riboflavin)
Vitamin B2 helps convert ingested carbohydrates, fats, and proteins into energy. It takes several months after insufficient intake to develop deficiency symptoms.

Vitamin B3 (Niacin)
Vitamin B3 plays a crucial role in transforming glucose into energy in mitochondria, the cell’s powerhouse.

Vitamin B5 (Pantothenic acid)
Pantothenic acid is essential for the release of energy from food and optimal growth. Besides, it helps fight infections by producing disease-fighting proteins called antibodies.

Pyridoxine (vitamin B6)
Pyridoxine comprises three biologically active molecules – pyridoxine, pyridoxal, and pyridoxamine. It is a critical component of the enzymes, which metabolize protein and glucose. In addition, vitamin B6 helps to convert tryptophan into niacin.

Biotin (vitamin B8)
Biotin is also called vitamin B8. It helps: (1)
• Synthesize fatty acids
• Break down protein
• Produce glucose from nonsugar molecules, such as amino acids.

Folate (Vitamin B9)
Vitamin B9 does not have a direct role in energy production in the cells.

Nonetheless, its deficiency can cause fatigue. Folate helps your body make RBCs (red blood cells). Inadequate RBCs cause anaemia – folate-deficiency anaemia.

Anaemia reduces oxygen supply to your cells. As a result, you may experience tiredness.

Cobalamin (vitamin B12)
Vitamin B12 helps break down food to generate glucose which is your body’s primary source of energy. Your body needs vitamin B12 to synthesize DNA.

Why Older Adults Are More Likely to Have Vitamin B Deficiency
Several factors contribute to vitamin B deficiency in seniors. They tend to eat less as they are satisfied with little food. Some may have medical conditions that can impair absorption, such as a gastric ulcer.

With increasing age, our ability to absorb nutrients from the intestine declines. It leads to a condition known as malabsorption. (2)

It is a significant cause of deficiencies of folate and vitamin B12. Malabsorption may also occur after surgery that removes a part of the digestive tract.

Regular use of medications, smoking, and alcohol use can further increase the risk. For example, (3)

● Vitamin B12 deficiency is common in those who take drugs for heartburn. Examples include proton pump inhibitors and H2-blockers.
● Folate deficiency in those who smoke or take drugs for cancer and pneumonia
● Thiamine deficiency in those who take water pills (diuretics)
● Pyridoxine deficiency in those who take drugs to relieve constipation

Exploring the Role of Diet and Diet Trends
The typical Western diet is often deficient in many vital nutrients and contains high amounts of unhealthy fats and sugar. (4)

Refined sugar and saturated fats promote inflammation. Long-term inflammation is a well-established cause of several diseases. These include diabetes, cardiovascular disease, cancer and arthritis. (5)

The Western diet can contribute to vitamin B deficiency in three ways.

● First, the food itself is low in many B vitamins, notably vitamin B12.
● Second, it causes inflammatory diseases that impair intestinal absorption. For example, inflammatory bowel disease (IBD) affects absorption. It may cause folate and vitamin B12 deficiencies.
● Third, it causes an imbalance in the gut microbiome that may affect absorption.

Diet Trends & Vitamin B12 Deficiency
There is a trend of people moving towards more plant based diets. The number of vegans in the UK increased fourfold between 2006 and 2018. (6) A vegetarian or vegan diet is considered healthier due to their low-fat content and high fibre content.

The term “vegan” and “vegetarian” does not by definition mean that a person has a healthy diet. It is possible to avoid meat and dairy but still have a plate of food devoid of nutrients.

Vitamin B12 is readily available in meat, fish and eggs but in a purely plant based diet sources are less obvious and it can be easy not to get enough vitamin B12 e,g Nutritional yeast like marmite, fortified Plant Milk (soy, almond, coconut, rice), Tempeh, Algae/seaweed, Mushrooms.

Vitamin B12 deficiency can be an issue and can cause anaemia and nerve damage. In some cases, neurological symptoms may not go away even after supplementation.

If a person is not taking the necessary steps to get enough Vitamin B12, it may also imply they are missing out on other B vitamins which in turn can contribute to tiredness.


When we consider that there are 8 B vitamins and understand their role in our energy, it reinforces the importance of a diet rich in nutrient dense foods.

Green leafy vegetables, legumes (beans and lentils), fruits (citrus, bananas, avocado), meat, poultry and fish, eggs and dairy are all sources of B Vitamins.

Generally speaking a rich and varied diet with plenty of colour (vegetables) will tick most of your nutritional boxes and ensure you get a plentiful amount of B vitamins regularly. Processed foods, foods high in fat and sugar typically lack B vitamins and of course, other nutrients.

“Fortified food”s have added Vitamins which is similar to supplementation and this can be a good way to get nutrients you are lacking.

Finally if you aren’t getting enough B vitamins, Vitaliti has all 8 B vitamins in slightly larger doses than than the minimum levels and contains 28 vitamins and minerals, plus supergreens and an amino blend.

If your diet isn’t giving you all that your body needs consistently, then Vitaliti can be a helpful top up of your daily nutrient needs.


  1. Nutrients. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence
  2. US Pharmacist. Vitamin Deficiencies in Seniors
  3. Public Health Nutrition. Relationship of tobacco smoking with serum vitamin B12, folic acid and haematological indices in healthy adults
  4. University of California – Davis Health. Western diet rich in fat and sugar linked to skin inflammation.
  5. Harvard Health Publishing. Understanding acute and chronic inflammation
  6. BBC Future. Are there health benefits to going vegan?