15 years ago, there was already a large amount of patient-led advice and anecdotal experience, but very little good-quality evidence that any particular diet treated ME/CFS itself. The NICE evidence base guidelines (2007) recommended a healthy balanced diet and regular meals and specifically said that special exclusion diets were not generally recommended.
In the latest recommendations in 2021 there was a big shift in emphasis with ME/CFS and nutrition, to awareness of risk of undernutrition or malnutrition. Those with ME/CFS who become more severely affected need more help with food shopping, meal preparation and even eating and are likely to be nutritionally compromised. Some struggle to eat and chew, are unable to manage enough, and lose weight unintentionally. It is important to identify risk of malnutrition, assess and treat as early as possible, with referral to a dietitian, to reduce the additional serious burden of malnutrition.
15 years ago thinking on ME/CFS (previously known as Chronic Fatigue Syndrome (ME)) included:
ME is caused by nutritional deficiencies. Fatigue was thought by some to be a lack of B vitamins, iron, magnesium, etc. Supplements could treat or cure ME/CFS.
Our understanding now is that deficiencies can certainly worsen fatigue and should be identified and treated. Recently, the importance of an adequate Vitamin D blood level and intake has been one example, especially during the Covid pandemic, however there was no evidence that ME/CFS as a whole was caused by nutritional deficiency. The latest NICE guidelines on ME/CFS (October 2021) clearly state that there is no evidence that supplements can treat or cure ME/CFS.
High-dose vitamin and mineral supplements. Large doses of B vitamins, vitamin C, magnesium, zinc and others were promoted as ways to increase energy or “correct” cellular dysfunction.
NICE now specifically cautions against high doses of supplements, as these can cause harm. There is insufficient evidence that routine high-dose supplementation treats ME/CFS.
Antioxidants. The theory of oxidative stress led to enthusiasm for vitamins C/E, selenium, CoQ10 and antioxidant combinations. Oxidative stress remains an area of research but this did not show that supplementation improves ME/CFS.
CoQ10/NADH. These were particularly popular because of theories about mitochondrial energy production. Some small studies produced encouraging findings, but evidence was insufficient to recommend them routinely. A later systematic review found only limited signals for NADH and NADH + CoQ10.
Low-GI / “slow-release carbohydrate” diets. Maintaining stable blood glucose was thought to reduce fatigue.
Regular, small meals and more wholegrain, less processed “slow- release carbs” can be useful, but ME/CFS is not established as a disorder caused by unstable blood glucose.
Many questions about the role of diet in ME/CFS remain unanswered, as diet research is limited and evidence is scarce.
Sugar-free/low-sugar diets. Sugar was said to cause “energy crashes”, insulin problems and inflammation.
Whilst reducing added sugar is recognised to help general good health, and would improve diet quality, there was no evidence that eliminating sugar altogether treated ME/CFS. This is reflected in the NICE guidelines.
Yeast/candida diets. Many years ago, “Candida overgrowth” was proposed as an underlying cause of chronic fatigue, with restrictive anti-yeast diets promoted.
However, there has since been research showing that there was no evidence that the anti-candida diet helps in ME/CFS. The research also showed how difficult this restrictive diet was to adhere to.
In summary there are still many questions unanswered about diet and ME/CFS. The complexity of diet research, and lack of evidence continues, and makes diet claims open to speculation.
Sue Luscombe RD September 2026