Chronic fatigue — persistent tiredness not resolved by sleep — is one of the most common complaints in UK primary care. While chronic fatigue has multiple potential causes (thyroid dysfunction, anaemia, depression, sleep disorders, viral illness), nutritional deficiencies are among the most common and most easily corrected underlying contributors. This guide covers the nutritional assessment and intervention approach for persistent tiredness. For related reading, see our vitamin D deficiency guide, our magnesium guide, and our blood sugar management guide.
The nutritional deficiencies most associated with fatigue
Iron deficiency (even without anaemia) is the most common nutritional cause of persistent fatigue in UK adults, particularly women of reproductive age. Vitamin D deficiency (affecting 1 in 5 UK adults) produces fatigue, low mood, and muscle weakness. Magnesium deficiency impairs ATP (energy) synthesis and sleep quality. B12 deficiency (particularly in vegans, older adults, and those with gut absorption issues) produces neurological fatigue and cognitive impairment. Coeliac disease produces fatigue through malabsorption even when gastrointestinal symptoms are absent or subtle.
Blood glucose instability as a fatigue driver
The mid-morning crash, the 3pm slump, and the post-lunch fatigue experienced by most UK office workers are not physiological inevitabilities — they are the direct consequence of blood glucose instability from refined-carbohydrate-heavy eating patterns. See our blood sugar management guide and our afternoon slump guide for the full picture. Stabilising blood glucose through protein-forward, complex-carbohydrate meals with adequate fat is often the fastest and most impactful nutritional fatigue intervention available.
When to see a GP
Persistent fatigue lasting more than four weeks warrants a blood panel with your GP: full blood count (anaemia, infection markers), iron studies (ferritin, transferrin saturation), thyroid function (TSH, free T4), vitamin D, vitamin B12, folate, and blood glucose. These tests identify the most common correctable causes. Nutritional changes are most effective when targeted to identified deficiencies rather than applied broadly — a GP-requested blood panel takes the guesswork out of nutritional fatigue management.
For more health and nutrition guidance, explore the Vanda's Kitchen blog. Our certified halal, 100% nut-free kitchen at Carter Lane EC4 delivers freshly prepared food to City offices daily. View our team lunch menu or WhatsApp us. Full allergen labelling on every item. Selfridges quality standard. Contact us about corporate catering.