The efficacy and safety of nutrient supplements in the treatment of mental disorders: a meta‐review of meta‐analyses of randomized controlled trials

FAB RESEARCH COMMENT:

This comprensive review adds to the already substantial evidence showing the fundamental importance of nutrition to psychiatry.

The authors systematically reviewed all meta-analyses of clinical trials investigating specific nutrients for specific psychiatric conditions, and found several areas where clear benefits have already been established, notably:

• long-chain omega-3 fatty acids (and EPA in particular) for clinical depression (and see Guu Et Al 2019 - ISNPR Practice Guidelines For Omega-3 Fatty Acids In The Treatment Of Major Depressive Disorder)

• long-chain omega-3 fatty acids for ADHD 

 as well as others where evidence is still emerging or preliminary, such as: 

• Vitamin B9 (folate) for depression and schizophrenia - but particularly in a special form (methylfolate), rather than as folic acid
• N-Acetyl Cysteine for depression, schizophrenia and other mental health conditions

The fact that the highest level of evidence (systematic reviews and meta-analyses of clinical trials) already supports some nutritional supplements as adjunctive treatments for mental health disorders is obviously very positive.

However, clinical trials of 'specific nutrients for specific conditions' can rarely address many important issues, such as:

1. psychiatric disorders - as currently diagnosed - are highly heterogenous, and yet most clinical trials focus only on broad diagnostic categories
2. co-occurence / overlap of different mental health problems in the same individual is very common, which adds to the clinical variability
3. nutrients work in synergy - not in isolation  - and yet nutritional status is often unknown in clinical trials even for the nutrient being supplemented - let alone for other nutrients that may be needed for this to be effective 

For these reasons, meta-analyses of clinical trials are likely to understate the potential benefits that could be obtained from more individuaised nutritional management. 

Good clinical practice always involves considering the patient's individual symptom profile, and their overall diet and nutritional status, as well as their general health. 

As the authors note, these factors are also important in designing the further clinical trials still needed in many areas.

See the associated news articles:

• World's largest evidence review: Nutritional supplements for mental health

• Do Nutrient Supplements Have Any Effect on Mental Disorders? - World's largest review of the evidence

For just some of the key reviews in this area, see also:

• Firth Et Al 2019 - The Effects Of Dietary Improvement On Symptoms Of Depression And Anxiety

• Firth Et Al 2018 - Diet As A Hot Topic In Psychiatry: A Population‐Scale Study Of Nutritional Intake And Inflammatory Potential In Severe Mental Illness

• Firth Et Al 2018 - Adjunctive Nutrients In First-Episode Psychosis: A Systematic Review Of Efficacy, Tolerability And Neurobiological Mechanisms.

• Firth Et Al 2017 - Nutritional Deficiencies And Clinical Correlates In First-Episode Psychosis

• Marx Et Al 2017 - Nutritional Psychiatry: The Present State Of The Evidence.

• Sarris Et Al 2015 - Nutritional Medicine As Mainstream In Psychiatry