Vitamin B12 deficiency symptoms: what you notice, who is more at risk and when to see your GP

In this article, you will read about the symptoms of vitamin B12 deficiency, who is more at risk, where B12 is found and when your symptoms are a reason to see your GP. That matters, because some groups are clearly more at risk.⁠¹ BioProfile's lifestyle scan gives you an indication of where you stand today in how you live and age. This is not a diagnosis. It is insight, to see where you stand today and to help you make better choices in your diet and lifestyle. The scan does not measure your B12 level and does not identify a cause. Only a doctor can assess that.

Vitamin B12 deficiency symptoms: what you notice

Thuisarts describes two groups of symptoms. The first group is nerve symptoms: tingling in your hands and feet, reduced feeling in your fingers, the feeling of walking on cotton wool and problems with your balance. The second group is the symptoms of anaemia: feeling tired and weak, getting short of breath during exertion, dizziness, a fast heartbeat, headache and ringing in your ears.⁠¹ In a clinical review article, tingling or numbness on both sides of the body and problems with walking were the most common nerve symptoms.⁠²

In short: vitamin B12 deficiency symptoms can show up in your nerves, in your energy or in both. Tiredness on its own has many possible causes, but tingling in both feet is a more specific sign.

Who is at greater risk

The most common cause of a severe deficiency is autoimmune gastritis, also known as pernicious anaemia: the body attacks the stomach lining, and B12 is no longer absorbed. In large case series, the median age of the people affected was 70 to 80 years. A milder form of thinning stomach lining, in which the B12 in food does not come loose from its protein, occurs in up to 20 per cent of older people.⁠²

So age plays a part on its own: an older stomach can release less B12 from food, even from a good diet. It is one of the quieter changes that come with the years. You can read what else shifts in what changes as you get older.

Thuisarts also names these groups: people who eat only plant-based food without products with added B12 or a supplement, people with stomach or bowel conditions such as Crohn's disease and ulcerative colitis, people who drink a lot of alcohol every day and eat poorly, people who take omeprazole or metformin, and people who regularly use nitrous oxide.⁠¹

Two medicines have been studied well. In a Dutch study of 390 people with type 2 diabetes who were followed for just over four years, B12 levels at the end were about a fifth lower with metformin than with a placebo. About 7 extra people in every 100 developed a deficiency.⁠³ In a large American study, people with a B12 deficiency had more often taken a stomach acid reducer for two years or longer (12 per cent versus 7 per cent). The link was clearly stronger at higher doses.⁠⁴

What this means for you: if you have been taking one of these medicines for years and you notice the symptoms above, that is something to discuss with your GP. Do not stop a medicine on your own.

Among people who eat plant-based, a review of 40 studies in vegetarian adults found that between 0 and 86.5 per cent had a deficiency, and vegans who took no supplement ran a particularly high risk.⁠⁵ Put simply: if you eat a fully plant-based diet without getting B12 from fortified foods or a supplement, you will probably end up with a deficiency.

Vitamin B12 deficiency symptoms: when to see your GP

Thuisarts advises contacting your GP if you have signs of anaemia, if you have nerve symptoms such as reduced feeling or tingling in your fingers, if you eat a fully plant-based diet and have symptoms that fit with it, or if you have symptoms while taking stomach acid reducers such as omeprazole, or metformin.⁠¹

Where vitamin B12 is found and how much you need

Adults need 2.8 micrograms of vitamin B12 a day. B12 is found in animal products. Per portion, the Voedingscentrum lists salmon (100 grams) with 4.0 micrograms, beef (75 grams) with 1.6, an egg with 0.8, a glass of milk (150 ml) with 0.7 and yoghurt (150 ml) with 0.6. Vegans are advised to use products with added B12 and a supplement that matches the daily amount. Most other people do not need a supplement.⁠⁶

A Dutch study in older people found that the blood markers for B12 improved as intake rose, but levelled off above an intake of about 5 micrograms a day.⁠⁷ This means a varied diet with some animal products covers most of what you need. Above that point, eating more made little difference to blood levels.

Tablets, injections and taking B12 yourself

If a deficiency is found, Thuisarts mentions tablets of 1,000 micrograms (1 milligram) a day for 3 months.⁠¹ High-dose tablets work about as well as monthly injections to bring blood levels and nerve findings back to normal.⁠² A Cochrane review of three small studies found no meaningful difference in blood levels between tablets and injections. The evidence was of low quality, and tablets cost less.⁠⁸

There is no proof that more is better. In a Dutch cohort of 5,571 adults followed for about eight years, the people with the highest B12 levels died about twice as often as the people with the lowest levels. After the researchers took other factors into account, a higher level was still linked to a slightly higher risk. The researchers write that the reason is unknown, and the study does not show that B12 itself causes harm.⁠⁹ For you, this means that taking B12 without a reason is not a free extra. If you have symptoms, talking to your GP comes first.

What the lifestyle scan measures and what it does not

The lifestyle scan looks at how you live and age, and gives you a starting point to compare against later. The scan does not read a B12 level, and tingling or tiredness can have many causes that the scan does not show. The scan is not a diagnosis. If you want to know what lifestyle has to do with the pace at which you age, biological age versus calendar age explains the difference.

In summary

Symptoms of vitamin B12 deficiency include nerve problems, and the tiredness and shortness of breath that come with anaemia. Older people, plant-based eaters without B12, people with stomach or bowel conditions and long-term users of metformin or acid reflux medication are more at risk. Animal products provide your B12. Most people get enough, but vegans need a supplement. If you have symptoms, your GP is the place to go. The lifestyle scan gives you insight into how you live and age.