are you tired or vitamin b12 deficient

Vitamin B12: how to tell if you’re B12 deficient or just tired

Posted by for Nutrition

Vegans are always being warned of the dangers of being vitamin B12 deficient, but how common is the deficiency and what impact can it have on fitness goals? SWTC investigates.

On going plant-based, there are two concerns that most friends and family become obsessed with: your protein intake and your vitamin B12 levels. The chat around whether we should be taking protein supplements, for the most part, is a moot point; you can eat enough protein to satisfy your muscle needs by eating a balanced, whole foods diet that contains plenty of soy and a wide variety of vegetables and pulses. B12 is slightly different.

Vitamin B12 deficiency is often cited as the main reason for not following a vegan lifestyle. That’s because it’s a nutrient often found in animal-based products, without which, you may struggle to get enough. Aside from hysterical health columns in newspapers, how common is vitamin B12 deficiency, and what impact can it have on our fitness goals if we really are running low?

According to a 2019 paper published in the British Medical Journal, between six and 12% of adults under 60 are vitamin B12 deficient, and according to dietitian Dr Carrie Ruxton from the Health & Food Supplements Information Service (HSIS), that number is closer to 20% for those who have “marginal vitamin B12 status.”

Elderly people, pregnant women, those following largely or wholly plant-based diets are more susceptible to the issue, with a low consumption of animal-source foods being the main cause of low vitamin B12 in younger adults. In older people, however, Dr Ruxton says that “B12 malabsorption from food becomes the predominant cause of deficiency, at least in part due to lack of gastric acid which carries the intrinsic factor important for the absorption of B12.”

If you’re on medications like metformin for diabetes or H2 blockers and tablets for stomach acid issues, that can also cause B12 deficiency.

The issue is that many of us simply aren’t aware of what B12 does in the body and what a lack of it can do to our health. “A report on plant-based diets commissioned by HSIS found considerable ignorance about vitamin B12 in that only 17% of people surveyed thought that low B12 might be a problem in vegan diets and only 25% thought it might be an issue with vegetarian diets,” Dr Ruxton explained.

That chimes with the experiences of registered dietitian Catherine Rabess, who tells Stylist that she’s “certainly seen it more and more in [my] clinic with younger people.” That, she says, may be down to having a “poor education around vegan diets, following restrictive fad diets or generally having a poor diet for a long time.”

How low B12 can affect your fitness goals

Firstly, it’s important to know what B12 does in the body. Its main role is to make red blood cells and maintain a healthy nervous system.

Symptoms of a deficiency include: 

  • Tiredness
  • Anaemia
  • Muscle weakness
  • Changes in mood and concentration

All of these may affect your energy levels and exercise performance. In extreme cases, it can also lead to nerve damage. To get more technical, Rabess explains that “the deficiency leads to abnormally large red blood cells that cannot do important functions adequately, such as carrying oxygen around the body using haemoglobin or keeping the nervous system healthy.”

GP Dr Nisa Aslam, also from HSIS, says that warning signs can also include “sore or red tongue, mouth ulcers, pins and needles, poor memory, and a change in the way you walk.”

If you regularly feel shattered, even after a good night’s sleep, and you’re experiencing any of these symptoms, it’s definitely worth thinking about how much B12 you’re consuming. If you’re worried, why not chat with your GP? There are any number of reasons why you might be feeling tired but generally speaking, tiredness should go away if you’re getting enough sleep and if it doesn’t, it’s probably time to look at things like your diet.

Vitamin B12 primarily exists in animal-based foods but many foods are fortified with it too.
Vitamin B12 primarily exists in animal-based foods but many foods are fortified with it too.

How common is B12 deficiency?

Registed dietician, Harpeet Sohal, confirms that B12 deficiency tends to affect around 6% of adults under 60, 11% of vegans and up to 20% of the over-60s. So, how does that compare with other vitamin shortages?

The most common deficiency in the UK is vitamin D, with the most recent UK National Diet and Nutrition Survey data (NDNS) showing that 16% of adults (aged 19-64 years) have vitamin D plasma levels below the UK threshold. Dr Ruxton cites a study in UK primary care that found that amongst 210,502 patients who had a vitamin D test, one-third were deficient (with deficiency identified as a blood level below 30nmol/litre). “Deficiency among ethnic minority groups ranged from 43% among those of mixed ethnicity to 66% of people from Asian backgrounds.”

She goes on to explain that 25% of girls and women aged 19-64 have intakes of iron below the recommended amount – putting them at risk of anaemia – and 36% have low levels of selenium.

How to get more B12, even if you’re plant-based

It’s more than possible to top up your levels of the vitamin from food sources if you are plant-based or trying to cut down on your meat consumption. “Vitamin B12-fortified foods are reliable plant-based sources. These include: yeast extracts like marmite and nutritional yeast flakes (often known as ‘nooch’), breakfast cereals, non-dairy milks, non-dairy yoghurts and spreads,” explains Sohal.

The Vegan Society recommends eating fortified foods at least twice a day to get a total daily intake of at least three micrograms (mcg), so Sohal recommends that it’s worth checking the labels of any processed foods you eat to see if they’ve had B12 added.

Rabess suggests that as eggs and dairy foods contain vitamin B12, it’s unlikely omnivores will have insufficient amounts in their bodies. However, “it only occurs naturally in foods of animal origin. Fermented foods such as nori, chlorella, spirulina, algae and nutritional yeast or yeast extract cannot be relied on as adequate or practical sources of vitamin B12 completely as absorption varies greatly depending on individual needs.”

Sohal agrees: “Most people will be able to get enough vitamin B12 from a varied, balanced diet. You only need to consider a vitamin B12 supplement if you fall into the at-risk groups mentioned above. Always check with a dietitian, doctor or pharmacist before taking any supplements.”

That means that vegans, in her opinion, should look to eating vitamin B12-fortified foods or vitamin B12 supplements daily. “Even lacto- and lacto-ovo-vegetarians could benefit from vitamin B12-fortified foods or supplements, as one cup of milk and one egg per day does not provide enough vitamin B12 to meet the dietary recommendations for this nutrient.”

Dr Ruxton agrees: “The HSIS report found that plant-based diets require a significant amount of planning to provide recommended amounts of nutrients. This is because nutrients from plant-based foods are less bioavailable than those from animal sources, and many people don’t research or plan when they switch.”

The same report found that over 60% of veggies or vegans hadn’t done any research on health before changing their diets. If you are planning on cutting down on animal products, it’s worth chatting with your GP or consulting a registered nutritionist for advice on eating the full gamut of nutrients.

Check out our other nutrition tips, healthy recipes and workout ideas in the Strong Women Training Club library.

Images: Getty

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Miranda Larbi

Miranda Larbi is the editor of Strong Women and Strong Women Training Club. A qualified personal trainer and vegan runner, she can usually be found training for the next marathon, seeking out vegan treats or cycling across London on a pond-green Tokyo bike.

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