Randomized Controlled Trials (RCTs) are a rarity in nutrition research, making the study we are reviewing this week particularly intriguing. This unique trial challenges the commonly accepted notion of the healthiest diet, leading to surprising findings: essentially, nothing significant.
In 1980, the inaugural Dietary Guidelines for Americans advocated for a varied diet. This recommendation emphasised selecting foods from major groups, including fruits, vegetables, cereals, meats, eggs, and dairy. The 2005 guidelines brought about two key changes: the introduction of Acceptable Macronutrient Distribution Ranges (AMDRs) and the Dietary Approaches to Stop Hypertension (DASH) diet, incorporating whole grains, vegetables, fruits, and low-fat dairy, while limiting sugar.
Over nearly two decades, countless institutions worldwide have incorporated this diet into their menus, and medical professionals are compelled to endorse it. Given the global impact of this specific diet on health, one would expect substantial evidence backing its claims. Surprisingly, the evidence is far from robust, mainly stemming from observational studies that infer associations between diet and health without rigorous trials.
A recent exception to this trend is the study by Barnes et al. (2023), published on July 18th, examining the MIND diet's impact on preventing cognitive decline in older individuals. The MIND diet, or Mediterranean–DASH Intervention for Neurodegenerative Delay, is a hybrid of the Mediterranean and DASH diets. Gary Taubes noted that the acronym's presumption that the diet successfully delays neurodegenerative decline is rather biased.
This study aimed to address the limited clinical trial data on dietary patterns and cognitive decline prevention. Conducting an RCT in nutrition is resource-intensive and complex, as seen in this large three-year study recruiting participants from Chicago and Boston. Individuals aged 65 and above, with a family history of dementia but without cognitive impairment, were included. The Montreal Cognitive Assessment was employed to assess cognitive status.