Effect of Low-Fat Diet on Depression Score in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials.
Study Goal
The researchers aimed to determine the effect of a low-fat diet (fat intake ≤30% of energy intake) on depression scores in adults through a systematic review and meta-analysis of randomized controlled trials.
Results Summary
The study found no significant overall change in depression scores with a low-fat diet compared to a usual diet, but noted small improvements in mentally healthy participants and when protein intake was adequate (15-20% of calories). The effect size was modest, and the certainty of evidence was low.
Population
Adults, including mentally healthy participants and those without baseline depression.
Effective Dosage
Fat intake ≤30% of energy intake; protein intake 15-20% of calorie intake in some subgroups.
Duration
Not specified in the abstract.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low-fat (LF) diet | no change | depression score | adults | Hedges g = -0.11; 95% CI, -0.25 to 0.03; P = 0.12 | no significant change | #1 |
LF, normal protein diet | decrease | depression score | - | Hedges g = -0.21, 95% CI, -0.24 to -0.01, P = 0.04 | significant improvement | #2 |
usual, normal protein diet | decrease | depression score | - | Hedges g = -0.28, 95% CI, -0.51 to -0.05, P = 0.01 | significant improvement | #3 |
LF diet | decrease | depression score | participants without baseline depression | - | improved | #4 |
LF diet | decrease | depression score | mentally healthy participants | - | small beneficial effect | #5 |
adequate dietary protein | decrease | depression scores | - | - | better intervention | #6 |
CONTEXT: Current evidence on the effect of a low-fat (LF) diet on depression scores has been inconsistent. OBJECTIVE: To explore the effect of an LF diet on depression scores of adults by systematic review and meta-analysis of randomized controlled trials (RCTs). DATA SOURCES: The PubMed, ISI Web of Science, Scopus, and CENTRAL databases were searched from inception to June 7, 2023, to identify trials investigating the effect of an LF diet (fat intake ≤30% of energy intake) on the depression score. DATA EXTRACTION: Random-effects meta-analyses were used to estimate pooled summary effects of an LF diet on the depression score (as Hedges g). DATA ANALYSIS: Finding from 10 trials with 50 846 participants indicated no significant change in depression score following LF diets in comparison with usual diet (Hedges g = -0.11; 95% CI, -0.25 to 0.03; P = 0.12; I2 = 70.7% [for I2, 95% CI, 44%, 85%]). However, a significant improvement was observed in both usual diet and LF diets when the content of protein was 15-20% of calorie intake (LF, normal protein diet: n = 5, Hedges g = -0.21, 95% CI, -0.24 to -0.01, P = 0.04, I2 = 0%; usual, normal protein diet: n = 3, Hedges g = -0.28, 95% CI, -0.51 to -0.05, P = 0.01, I2 = 0%). Sensitivity analysis also found the depression score improved following LF diet intervention in participants without baseline depression. CONCLUSION: This study revealed that LF diet may have small beneficial effect on depression score in the studies enrolled mentally healthy participants. Moreover, achieving to adequate dietary protein is likely to be a better intervention than manipulating dietary fat to improve depression scores. However, it is not clear whether this effect will last in the long term. Conducting more studies may change the results due to the low-certainty of evidence. SYSTEMATIC REVIEW REGISTRATION: CRD42023420978 (https://www.crd.york.ac.uk/PROSPERO).