Why Are So Many of Us Tired All the Time? The Nutritional Reasons Behind Fatigue
Fatigue is common but complex. If you often feel tired without any apparent cause, nutritional deficiencies might be the culprit. Read on to find the most common nutritional causes of fatigue in the UK population.
What Is Fatigue?
Fatigue is a subjective feeling of being tired that can vary from one person to another. One may describe fatigue as sleepiness, while others may call it weakness or a lack of energy.
Other terms used to describe fatigue can include decreased exercise tolerance (decreased ability to do physical activity), feeling down, or shortness of breath when exercising.
There is no universally accepted definition of fatigue. However, most health experts agree that it is a decline in mental and physical performance, which may result due to:
- Prolonged exertion
- Impaired sleep
- Disruption of the body’s internal clock (the part of the brain that regulates your sleep-wake cycle)
Fatigue is often neglected, as many consider it a normal part of aging. Though associated with aging in most cases, long-term fatigue is not a normal part of aging.
How Fatigue Affects Our Lives
Severe or long-term fatigue can be debilitating, affecting our ability to perform daily activities. It can directly affect the quality of life.
There is a close relationship between fatigue and the risk of mental illness. For example, according to a study, up to 66% of people experiencing fatigue for over six months will likely develop a coexisting mental disorder. (1)
A 2024 study analysing the data of 2743 participants found that fatigue can double the risk of leaving work due to poor health. (2)
Understanding Fatigue at the Cellular Level
At the cellular level, chronic inflammation and mitochondrial dysfunction are thought to contribute to fatigue.
Mitochondrial dysfunction
Mitochondria are organelles (tiny organs inside the cell) essential for survival. They generate energy in the form of ATP, which our cells use to function.
Mitochondrial dysfunction is when the mitochondria in our body cannot perform their task of generating energy for cells. What we eat is first converted to glucose and then to ATP in mitochondria.
Every cell in our body relies on ATP for energy to perform its task. When you have mitochondrial dysfunction, mitochondria cannot produce as much ATP as required, potentially leading to fatigue.
Mitochondrial dysfunction has also been associated with many long-term diseases, including diabetes, heart disease, Alzheimer’s disease, certain cancers, and recurrent infections. (3)
Chronic inflammation
Chronic inflammation may contribute to fatigue by causing an imbalance between energy availability and energy expenditure. In simple terms, when we have chronic inflammation, our cells spend more energy than the body generates. (4)
Chronic inflammation is also one of the contributors to loss of appetite, which may cause underfeeding and fatigue. Micronutrient deficiency may increase oxidative stress and hence, inflammation.
Related: Chronic Inflammation Is Widespread In the UK. Here’s What You Can Do to Keep It At Bay
What Nutritional Deficiencies May Cause Fatigue
Numerous studies show that low levels of vitamins A, D, E, folate, iron, zinc, and selenium can contribute to low energy levels, fatigue, and impaired well-being in the general population. (5)
Vitamin A
Vitamin A or retinol is a fat-soluble nutrient. Our body needs it to keep our immune system competent, help vision in low light, and maintain the integrity of the skin and other linings of the body.
In developed countries, vitamin A deficiency occurs mainly due to malabsorption, unlike in developing countries, where insufficient intake is the main cause of deficiency. Malabsorption may result due to severe chronic liver disease, chronic pancreatitis, and cystic fibrosis.
A drop in vitamin A level in the body increases oxidative stress, reduces ATP production, and causes mitochondrial dysfunction. (6) All these lead to cellular energy depletion and fatigue.
Vitamin D
Vitamin D is a fat-soluble vitamin. Our body needs it to keep our bones, teeth, and muscles healthy.
Vitamin D plays a crucial role in cellular energy metabolism and communication between nerves and muscles. Likewise, it improves mitochondrial function and reduces oxidative stress. Lastly, it reduces inflammation and increases the production of anti-inflammatory substances in the body. (7)
So, its deficiency is directly linked to increased fatigue and reduced muscle strength.
Note: The UK government recommends everyone in the UK to take a daily vitamin D supplement (10 micrograms) from October to early March.
Vitamin E
Vitamin E is a fat-soluble vitamin. It is a potent antioxidant that is essential for healthy eyes, skin, and immune system. Vitamin E deficiency is rare in the UK, often seen in people with pancreatic disease or digestive problems.
Low vitamin E levels can lead to rapid muscle fatigue and breakdown of oxygen-carrying blood cells, both of which can cause fatigue.
Iron
Iron is essential for making red blood cells, which carry oxygen from our lungs to tissues around the body. Iron deficiency can lead to iron deficiency anaemia, of which fatigue is a characteristic feature.
Iron deficiency is common in the UK. According to a 2025 study analysing over 30,000 samples from the UK, iron deficiency was found in about 33% of women and 3% of men. (8)
Vitamin B12
Our body needs vitamin B12 to make red blood cells. So, low levels can lead to anaemia, and hence fatigue. Most notably, even in the low normal range, vitamin B12 deficiency can cause noticeable symptoms of fatigue.
While most of us get enough vitamin B12 from our diet, the risk of deficiency is higher among older adults, those with certain digestive disorders, vegetarians, and vegans.
Zinc
Zinc is a micronutrient essential for making enzymes and processing dietary carbs, fat, and protein. We need zinc for DNA repair, ATP generation, and immune system regulation. Zinc also has powerful antioxidant and anti-inflammatory properties. (9)
Zinc deficiency can increase inflammation and prevent ATP from releasing energy, which can lead to fatigue. (10,11)
Selenium
Selenium is an essential mineral with potent antioxidant properties. It helps convert thyroid hormone into active form and regulates the immune system.
Selenium deficiency can increase inflammation and muscle fatigue. (12)
Dehydration and Fatigue: Is There A Link?
Dehydration is a common yet often overlooked cause of fatigue. Even mild dehydration can reduce blood volume, disrupt oxygen delivery, and cause brain fog. All these, together or independently, can lead to symptoms of fatigue.
How Are Nutrition and Fatigue Related?
There is a two-way relationship between undernutrition and fatigue. Nutritional deficiencies can lead to fatigue and fatigued people may be more likely to be undernourished.
Interestingly, overnutrition characterised by excessive food consumption, especially carbs and fat, may lead to obesity and impair sleep. Obesity alone may also be associated with sleep disorders. Both obesity and sleep disturbances can cause fatigue.
What Are the Best Nutrients for Chronic Inflammation and Mitochondrial Dysfunction?
The three ingredients scientifically backed to counter chronic inflammation are omega-3 fatty acids, vitamin D, and curcumin. Likewise, nutrients that help control mitochondrial dysfunction are carnitine, CoQ, creatine, and vitamin B2. (13,14)
When to See a Doctor
Talk to your GP if you:
- Have been feeling tired for several weeks without any obvious cause
- Cannot perform your daily activities because of fatigue and associated symptoms
- Also have other symptoms, including unintended weight loss or mood swings
- Have breathing problems while you are asleep
Stop Surviving, Start Thriving: Meet Vitaliti
If you are tired of being “tired all the time,” it’s time to move beyond caffeine and address fatigue where it starts, that is inside your cells.
Your body’s “internal power stations” (the mitochondria) require a specific suite of micronutrients to convert what you eat into usable energy (ATP). When these nutrients are missing, your metabolism stalls, and fatigue becomes your “new normal.”
We formulated Vitaliti to be the ultimate metabolic support system. Unlike standard multivitamins, Vitaliti is a high-strength liquid formula designed for maximum absorption, delivering the exact “energy catalysts” we’ve discussed in this article:
Mitochondrial Fuel: Packed with CoQ10, L-Carnitine, and B-Complex vitamins to help your cells generate energy more efficiently.
Anti-Inflammatory Support: High doses of Vitamin D3 and antioxidants to counter the chronic inflammation that drains your daily stamina.
Essential Minerals: Includes Iron, Zinc, and Selenium to support oxygen transport and thyroid health.
By providing your body with a surplus of these vital building blocks, you are refueling your system at the cellular level.
Ready to reclaim your energy?
Experience the liquid advantage with Vitaliti and give your mitochondria the support they deserve.
References:
- Harvey, Samuel B et al. “The relationship between fatigue and psychiatric disorders: evidence for the concept of neurasthenia.” Journal of psychosomatic research vol. 66,5 (2009): 445-54. doi:10.1016/j.jpsychores.2008.12.007
- Macfarlane, G J et al. “Impact of fatigue on work productivity and health-related job loss.” Occupational medicine (Oxford, England) vol. 74,6 (2024): 423-429. doi:10.1093/occmed/kqae056
- Nicolson, Garth L. “Mitochondrial Dysfunction and Chronic Disease: Treatment With Natural Supplements.” Integrative medicine (Encinitas, Calif.) vol. 13,4 (2014): 35-43.
- Lacourt, Tamara E et al. “The High Costs of Low-Grade Inflammation: Persistent Fatigue as a Consequence of Reduced Cellular-Energy Availability and Non-adaptive Energy Expenditure.” Frontiers in behavioral neuroscience vol. 12 78. 26 Apr. 2018, doi:10.3389/fnbeh.2018.00078
- Maggini, Silvia, et al. “Benefits of Micronutrient Supplementation on Nutritional Status, Energy Metabolism, and Subjective Wellbeing.” Nutrición Hospitalaria, vol. 38, no. Ext. 2, 2021, doi:10.20960/nh.03788.
- Chiu, Haw-Jyh et al. “Vitamin A depletion causes oxidative stress, mitochondrial dysfunction, and PARP-1-dependent energy deprivation.” FASEB journal : official publication of the Federation of American Societies for Experimental Biology vol. 22,11 (2008): 3878-87. doi:10.1096/fj.08-112375
- Di Molfetta, Ippolita Valentina et al. “Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review.” Nutrients vol. 16,2 221. 10 Jan. 2024, doi:10.3390/nu16020221
- Irvine, Allister et al. “Ironically unwell: anaemia and iron deficiency among health-aware adults in the UK.” Frontiers in nutrition vol. 12 1679989. 7 Oct. 2025, doi:10.3389/fnut.2025.1679989
- Wessels, Inga et al. “Zinc as a Gatekeeper of Immune Function.” Nutrients vol. 9,12 1286. 25 Nov. 2017, doi:10.3390/nu9121286
- Wessels, I., Haase, H., Engelhardt, G., Rink, L., & Uciechowski, P. (2012). Zinc deficiency induces production of the proinflammatory cytokines IL-1β and TNFα in promyeloid cells via epigenetic and redox-dependent mechanisms. The Journal of Nutritional Biochemistry, 24(1), 289–297. https://doi.org/10.1016/j.jnutbio.2012.06.007
- Takeda, Taka-Aki et al. “Zinc deficiency causes delayed ATP clearance and adenosine generation in rats and cell culture models.” Communications biology vol. 1 113. 22 Aug. 2018, doi:10.1038/s42003-018-0118-3
- Perri, G.; Mendonça, N.; Jagger, C.; Walsh, J.; Eastell, R.; Mathers, J.C.; Hill, T.R. Dietary Selenium Intakes and Musculoskeletal Function in Very Old Adults: Analysis of the Newcastle 85+ Study. Nutrients 2020, 12, 2068. https://doi.org/10.3390/nu12072068
- Youmshajekian, L. Three anti-inflammatory supplements can really fight disease, according to the strongest science. Scientific American. https://www.scientificamerican.com/article/three-anti-inflammatory-supplements-can-really-fight-disease-according-to/
- Zong, Y., Li, H., Liao, P. et al. Mitochondrial dysfunction: mechanisms and advances in therapy. Sig Transduct Target Ther 9, 124 (2024). https://doi.org/10.1038/s41392-024-01839-8
