Registered Dietitian Charlie Watson on what vitamins and minerals actually do for tiredness, which ones matter and when it is time to look beyond them.
Key Takeaways
Tiredness is usually a symptom, not a diagnosis: sleep, stress, underfuelling and nutrient gaps all play a part.
Vitamins and minerals don't provide energy. They help your body release it from food.
B vitamins, iron, magnesium and vitamin C are the nutrients most closely linked to energy and fatigue.
Lasting energy comes from a varied, colourful diet, good sleep and low stress, not quick fixes.
If you've felt tired for a few weeks despite sleeping and eating well, it's worth speaking to your doctor.
Charlie is a registered dietitian with six years of NHS experience, currently specialising as a neurology dietitian with a particular focus on Motor Neuron Disease. A former Deputy Cookery Editor at Good Housekeeping Magazine, she retrained as a dietitian out of a conviction that nutrition guidance should be evidence-based and led by qualified practitioners. Charlie is also a keen runner and passionate about helping everyday runners improve their performance and enjoyment through smarter fuelling.
Most people reach for a strong coffee, an energy drink or that mid-afternoon sugar fix when their energy levels start to dip.
They are looking for that quick burst of energy to get them through the final hours at work, a boost to get them through a workout, or the stamina to manage a kids' evening bedtime routine.
But have you ever thought about the role vitamins play in supporting your energy levels?
Popping a daily multivitamin won't give you the same instant buzz as your fourth espresso of the day (for good reason!). However, vitamins and minerals are absolutely essential in supporting your energy levels, and that includes allowing your body to actually use other tools like caffeine.
The phrase "I'm tired" can often be used as a bit of a catch-all but it's rarely caused by a single thing. Here are some of the most common:
The most obvious cause is a lack of sleep. Even a fairly minor reduction in sleep (say, getting six hours a night instead of seven or eight) can dull alertness and cognitive performance, which many of us notice as lower energy and a flatter mood.⊕ It can also be caused by a change in quality of sleep. Not getting enough deep or REM sleep can leave you feeling unrefreshed when you wake. Disruptions in sleep can impair muscle repair and recovery, hormone production and cognition.
Chronic stress can also take a toll on energy, and magnesium is one nutrient involved. Researchers suggest a two-way link: stress may increase magnesium loss, while low magnesium may make us more sensitive to stress.⊕ Magnesium is vital for brain and muscle function, so a shortfall is one more thing that can leave you performing below your best.
Undereating for your daily activities causes fatigue because your body doesn't have enough fuel to meet its energy demands. Your brain and muscles rely on glucose and stored energy to function, less food means less energy availability. Your brain can't store glucose (unlike your muscles) and when blood sugar drops, your brain gets less glucose leaving you feeling tired, groggy and can impact your ability to concentrate. Chronic underfuelling can impact hormone production, immune function and iron status which can affect ongoing fatigue.
Nutrient shortfalls can affect energy directly, too. A 2020 review found that deficiency in certain vitamins and minerals, including vitamin C and iron, is linked to fatigue.⊕
Your thyroid controls production of hormones that control your body's energy use and metabolism. An over or underactive thyroid can cause metabolism to either speed up or slow down respectively. An underactive thyroid doesn't produce enough T4 or T3 reducing your body's efficiency at energy production, whilst an overactive thyroid increases energy demands as your metabolism works overtime and affects sleep quality. Fatigue linked to thyroid problems often improves with treatment and support from healthcare professionals.⊕
The main takeaway is that most of the time fatigue is a symptom, rather than a diagnosis in its own right. It's important to understand the root cause of the problem before we start leaning on supplements. There's no point taking iron tablets, if what's actually causing your tiredness is stress. Much of the time it can require a multifaceted approach to tackling the problem, and once you've drilled down into that, there are a number of ways vitamins can help.
The most important thing to understand is that vitamins don't give you energy themselves, their role in energy production is to support your body into extracting it from the things that do provide sources of energy, including food and caffeine. They help to release energy, not provide it. Vitamins are like the workers or machinery in a factory. You can have all the raw materials you like, but without some help the production line will break down.
Vitamins like B Vitamins are converted into co-enzymes which help enzymes in our body to break down food to extract energy. For example, Thiamine (Vit B1) helps convert glucose into usable energy, while Vitamin B5 is converted to Coenzyme A and helps break down protein, carbs and fat by carrying them into your mitochondria – your cell's power stations.
Inside your mitochondria these vitamin dependent reactions allow nutrients to be converted into ATP (adenosine triphosphate), your body's main energy carrying molecule. Your brain, muscles and organs then use ATP to power thoughts, movement, and the body's daily functions.
If you're looking at improving your energy levels, there are a few key nutrients you want to pay attention to…
There are eight B vitamins but there are a few of them that are particularly important when it comes to energy release: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B9 (folate) and B12 (cobalamin).
Vitamin B6 plays a key role in amino acid metabolism, glycogenolysis and gluconeogenesis – all processes that regulate how the body produces and maintains energy levels.⊕
B12 deficiency is one of the most common and well documented. Without sufficient B12, your body can't produce enough healthy red blood cells which are needed to deliver oxygen to muscles and organs. Fatigue is one of the symptoms of low B12 levels.⊕
Those following plant-based diets need to be especially careful around B12 deficiency, as it's not naturally found in plant foods and will likely need to be supplemented. Older people can also be affected, as their gut absorption abilities lower.⊕
Low iron is one of the most common deficiencies worldwide and is routinely linked to iron deficiency fatigue. Without enough iron, oxygen can't be effectively delivered from the lungs to the rest of the body, which leaves you feeling tired, breathless and struggling to sustain effort, both physically and mentally.
Iron deficiency affects more than a billion people worldwide.⊕ It is particularly prevalent in menstruating women, pregnancy, endurance athletes and those following a vegetarian or vegan diet. Additionally those with conditions that struggle to absorb iron such as those with coeliac disease or inflammatory bowel disease.
Haem iron is the most easily absorbed and bioavailable form of dietary iron and is mostly found in red meat, poultry and fish sources. Pairing plant based, non haem dietary iron with a source of Vitamin C can significantly improve absorption.⊕
Magnesium helps run more than 300 enzyme systems in the body and is involved in a large number of bodily functions.⊕ In a small US Department of Agriculture study of postmenopausal women, a low-magnesium diet meant the volunteers needed more energy and more oxygen to do low-level activities.⊕
Magnesium levels also impact good sleep quality, as it is involved in the production of the sleep hormone melatonin.
One of vitamin C's most important roles when it comes to energy availability is how it supports absorption of plant-based iron sources. This isn't just the case over the course of a day: ideally, vitamin C needs to be consumed during the same meal as the iron. This could be pairing beans and bell peppers, lentils with tomatoes or a bowl of fortified cereal with a glass of orange juice in the morning.
"Vitamin C's involvement in energy-yielding metabolism and its role in reducing fatigue have been recognised in the EU's authorised health claims for nutrients – meaning the evidence for its role is considered robust enough for regulatory acknowledgement."⊕
Wherever possible, it's best if you can get your vitamins and minerals from whole food sources, rather than relying on supplements (however this isn't always possible!). Ideally we want to go for both variety and plenty of colour in our diet to maximise the range of vitamins and minerals ingested, as well as fibre!
Here are some effective sources for the main nutrients we've discussed so far…
Many of our go-to strategies to combat fatigue, like caffeine, provide a quick fix, but they don't improve your body's underlying ability to produce or utilise energy. In fact, caffeine doesn't actually provide your body with energy, instead it makes you feel more alert and reduces our perception of fatigue. Quick sources of energy, like a sugary treat at 4pm might be able to temporarily mask or overcome fatigue, but you're not getting to the bottom of what that fatigue is trying to tell you.
That's not to say there isn't a time and a place for caffeine or a sweet treat. It can be really helpful to temporarily override those fatigue signals during a race or give the body a quick glucose boost which is why so many athletes rely on carbohydrates before and during longer bouts of exercise. Many pro athletes use caffeine as an important part of their fuelling strategy (it is one of the most widely studied and utilised performance enhancers).
Day-to-day you want to be looking at creating lasting energy and vitamins and minerals play a very important role in this, allowing your body to generate energy at a cellular level. They help unlock the energy that is stored in the food that we eat, meaning that what we eat (ensuring adequate vitamin intake) is just as important for our energy levels and our ability to access sources of energy. A balanced diet should be paired with sufficient, good quality sleep and low stress levels for sustained, lasting energy levels.
As mentioned already, tiredness and fatigue are symptoms, rather than a diagnosis of their own. A good rule of thumb is that if you've felt consistently tired for more than four weeks, despite getting a good amount of sleep and eating a well-balanced diet, it might be worth speaking to a doctor.
The sort of things your doctor might want to test for include blood count (for anaemia), serum ferritin (iron stores), B12 and folate, vitamin D and thyroid function.
These tests might just be part of the ruling out process before starting investigations into other conditions. Fatigue can be associated with illnesses like thyroid disorders, coeliac disease, diabetes and various others.
Consistency is key and the most effective energy-supporting habits are often the unglamorous ones. Some good habits to try and focus on are…
The vitamins (and minerals) most linked to energy and fatigue are B Vitamins, iron, Vitamin C and magnesium.
B12 (found in meat, fish, poultry, eggs, dairy and some fortified dairy free milks & cereals) supports normal energy metabolism. It also plays an essential role in red blood cell production. Those following a vegan/vegetarian diet, adults over 60, and those with digestive conditions such as Coeliac or IBD are most at risk of B12 deficiency.
Iron deficiency is one of the most common nutrient deficiencies and is widely linked with fatigue. When it becomes severe enough it can lead to anaemia. Iron is required to make haemoglobin, the protein in red blood cells that carries oxygen from the lungs around the body. When iron levels are low, our muscles and organs receive less oxygen, making it harder to produce energy efficiently.
Menstruating women, pregnancy, those following a vegetarian/vegan diet and endurance athletes are most at risk of iron deficiency. It can present as persistently feeling low energy or tired, short of breath, brain fog, dizziness, pale skin, hair loss, brittle nails and reduced exercise performance. Your doctor or healthcare professional can organise a blood test to identify iron deficiency by taking a full blood panel and ferritin (stored iron) levels.
Energy drinks are a temporary stimulant and don't always provide the body with any actual energy e.g. sugar free caffeinated drinks. Caffeinated drinks work by blocking adenosine, the chemical that makes you feel sleepy and increasing alertness.
Ensuring adequate vitamin intake supports normal energy metabolism long term rather than a quick fix energy drink which simply 'papers over the cracks' and doesn't get to the bottom of the reasons for fatigue.
See your doctor if you've been feeling tired for a few weeks and can't explain why, or if your tiredness is affecting your daily life. It's also worth seeing a doctor if your tiredness comes with other symptoms such as weight loss or mood changes, or if you've been told you make gasping, snorting or choking noises when you sleep.⊕
