Is a B12 deficiency the reason you are tired all the time?

Why, at 25, I couldn't get through the day without a nap.

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Late last year I suddenly hit a phase where my energy plummeted and my normal upbeat, can-handle-anything demeanour slipped away. I began voicing the thoughts running through my head on the regular: “I’m just extra tired”, “I’m not sleeping great”, “I’m just overworking and over training” or “It’s a busy period right now.” Anything that could explain away why, at 25 years old, I felt like I couldn’t function for more than 2 hours a day.

Fatigue was something I was experiencing daily, and not the type where I had been out late the night before and needed a few extra hours kip – I’d wake up bone tired, regardless of how many hours sleep I’d had, be clutching for more coffee all morning and by mid-afternoon would be crashing again, desperate to stay in bed for the rest of the day.

I felt like I was walking with my head in a cloud – and not in the slightest bit in the romantic sense – but as I could only describe as a “foggy brain”. I couldn’t keep track of anything, my memory suddenly was patchy – I had been studying for a Personal Training qualification intensely for the first half of the year and come June my skills of simple recall had disappeared. Remembering where I had left my phone, keys or purse was a daily struggle. As for making decisions? I became more indecisive than ever and would completely zone out when faced with options.

I already knew my hormones were all over the place (I had just received a diagnosis of PCOS) but my feelings of anxiety, depression and irritability were sky-rocketing and I was unable to think or act rationally or calmly.

And then it got physical – balance and proprioception went out the window, I was having to work doubly hard to find my strength and support in movements that used to be second nature. And for strength in general? My body felt like mush, regardless of how I was working out. I felt like I was only able to operate at 50% capacity, regularly feeling like my legs would give way underneath me. I found it harder to draw deep full breaths when getting my heart rate up – often finding myself dizzy or struggling to recover in rest periods. Add on, extended periods where I was experiencing alternating numbness or tingling sensations in my arms and lower legs, I soon realised my body was trying to tell me something was up.

I rocked up to my functional doctor/Herbalist/Naturopath and began listing all my symptoms and worries, voice wobbling from the worry and anxiety that I was experiencing and barely able to remember when this all started. She quickly came back with an answer, which was then confirmed by my GP via bloodwork sent to the labs – I was severely deficient in B12.

What is B12?

Known as the “energy vitamin”, B12 is a necessary vitamin utilised by the human body to make red blood cells, nerves and DNA and carry out vital functions, whilst regulating the nervous system. As a vitamin, it cannot be created or replenished by the body, and as such must be received into the body via food (the preferred source) or supplementation. Whilst the liver can home B12 stores for up to 5 years, as we age and experience dietary or lifestyle changes, these stores can get depleted rather rapidly.

What’s the dose? On average, an adult requires approximately 2.4 mcg of B12 per day for optimal functioning.

Can we get it in food?

Luckily nature can provide us with some great sources of B12 rich food – however most are animal products or derivatives, with the top sources being shellfish, liver, fish, crab, red meat, eggs and dairy products such as- cheese, milk & yoghurt. Though it is possible to get B12 from other products such as nutritional yeast, fortified soy products, fortified cereals,

It’s super important to know that unfortunately plants don’t make B12 so strict vegetarians, vegans or those who follow a plant-based diet and don’t eat foritified products are at higher risk of B12 deficiency.

The link to the gut

While some people aren’t consuming enough B12 through their food sources, others simply cannot absorb enough of the vitamin no matter how much they try to eat. This is a common problem from those suffering with inflammatory issues of the gut and digestive tract, such as leaky gut, gluten intolerance, coeliac disease or Crohn’s disease. With malabsorption occurring, this vital vitamin is simply not getting transferred into the body to top up stores – so even if the diet is rich in B12 sources, the body is still being deprived of what it needs.

Why was this happening to me? I had recently started to adjust my diet to more plant-based and I have long struggled with optimal digestion – suffering from IBS symptoms and working with gluten intolerance and FODMAPs friendly meals – and when checking in with first my functional doctor/Herbalist and then my GP – they noted these were two major contributing factors to my plummet of B12 stores.


As we can store B12 in the liver for years at a time, a deficiency can be slow to develop, with symptoms that appear to intensify over time. Or it can also come on quickly. With an array of symptoms sometimes the condition is overlooked or shrugged off with “it’s a busy time”or “It’s just a rough patch” being common explanations for concerns. However an accumulation of these symptoms may have you doing a little more research into what is going on in your body.

Some of the trademark symptoms of B12 deficiency may include:


Your body relies on B12 to make red blood cells which carry oxygen to your organs. Without enough oxygen in your cells you’ll feel tired no matter how long you sleep.


The experience of feeling weak and sluggish, along with higher levels of fatigue, is common, as without enough oxygen your muscles will feel unable to push and display signs of weakness or overuse.

Strange Sensations

Sensations such as numbness, tingling, pins and needles in hands, legs or feet may occur from the low oxygen levels in the cells contributing to preliminary nerve damage.

Foggy Brain

Lowered cognitive function, with difficulty thinking and reasoning, slow cognitivte processing or memory loss.

Loss of accurate proprioreception 

Feeling off-kilter and often dizzy, especially when walking up and down stairs or when standing up.

Pale skin

The skin may lose its rosy tones, even reaching a yellowed appearance tones of jaundice as the red blood cells are easily broken leading to a pale, washed out appearance.


Due to B12 being needed to generate red blood cells it is possible that the body produces fewer red blood cells or abnormally large blood cells which do not operate properly in transporting oxygen around the body.


A lack of b12 wrecks havoc on mood increasing feelings of depression and anxiety. Whilst this link is not exactly determined by doctors, it may be associated to the synthesis of brain chemicals – serotonin and dopamine- which help regulate mood.

Loss of vision

In extreme cases, a B12 deficiency can damage the optic nerve or plug up the blood vessels in the retina causing blurry vision, double vision, sensitivity to light and even vision loss.

How is it tested?

My diagnosis came around first by a description of the collection of symptoms, which was then backed up by my GP recommending tests of my bloodwork. Whatever your preference – functional or traditional medicine – it is important to seek out and follow your doctors medical advice, with blood work being a more accurate way to assess the severity and remove the guesswork.

How do you boost your B12 back up?

Depending on the severity of your deficiency there are a variety of treatments that can be prescribed by your doctors. If you are severely deficient, you may be prescribed injections for consecutive weeks. For less severe cases, oral supplementation can be highly effective- with a range of sprays or tablets available on the market. I love the Better You B12 Spray and have been using it daily for the past 9 months or so.

As always, it’s also important to address diet and lifestyle factors, such as seeking help to heal and increase absorption of the gut and maintain a diet of whole foods that are rich in B12 sources – utilising the power of food to heal and prevent further illness.

These days, I notice pretty much straight away now if my B12 levels are slipping back down and make a point of checking in to symptoms and staying mindful of how my energy levels are. I manage this getting my levels checked out whenever I have blood work done to see how things are progressing. Whilst I do still follow a predominately plant based diet, I make sure to include loads of fish and eggs into my meals and keep on top of my supplementation to keep symptoms at bay.

Concerned about your B12 levels? Make sure you seek medical advice from your practitioner before starting any treatments.

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