The global aging population is experiencing a dramatic rise in non-communicable diseases (NCDs), placing a significant burden on healthcare systems. These NCDs encompass a wide spectrum, including cardiovascular diseases (CVDs), diabetes, various cancers, neurodegenerative diseases, psychological/neurological disorders, and digestive disorders. While the age-related nature of many of these conditions is well-established, understanding modifiable risk factors, such as diet, is crucial for prevention and promoting healthy aging. Previous research has linked specific dietary patterns, like the Mediterranean diet and Healthy Eating Index, to a reduced risk of some NCDs, particularly CVDs, diabetes, and certain cancers. However, the associations between dietary patterns and a broader range of individual chronic diseases, including neurological disorders, digestive issues, and other less-studied conditions, remain less clear. This study aims to address this gap by examining the associations of four commonly used dietary scores with the risk of 48 individual chronic diseases in a large population-based cohort study utilizing the UK Biobank database. The primary objective is to identify which dietary pattern is most strongly predictive of a reduced risk across the widest range of chronic conditions.

Existing literature demonstrates a strong link between healthy lifestyles and reduced chronic disease risk and mortality. Diet is a key modifiable lifestyle factor. Previous studies have shown that adherence to dietary patterns such as the Mediterranean diet, Healthy Eating Index, and Dietary Approaches to Stop Hypertension (DASH) is associated with a lower risk of CVDs, diabetes, and some cancers. However, the evidence regarding the relationship between dietary patterns and neurodegenerative diseases, such as dementia and Parkinson's disease, has been inconsistent. While the benefits of healthy eating on bone health and musculoskeletal disorders have been explored, less is known about its impact on other chronic conditions like respiratory diseases, digestive disorders, chronic kidney disease (CKD), eczema, endocrine disorders, and ophthalmic conditions. This study's comprehensive approach aims to fill these knowledge gaps by investigating the relationship between dietary patterns and a wide array of individual chronic diseases.

This study utilized data from the UK Biobank, a large prospective cohort study of over half a million individuals aged 39-70 at enrollment (2006-2010). After excluding participants with insufficient dietary data or extreme energy intake, the final analysis included 121,513 participants (55.9% female). Diet was assessed using a validated web-based 24-hour dietary assessment tool completed on at least two occasions. Four dietary scores were calculated: the Alternate Mediterranean Diet (AMED) score, the Alternate Healthy Eating Index-2010 (AHEI-2010), the Healthful Plant-based Diet Index (HPDI), and the Anti-Empirical Dietary Inflammatory Index (AEDII). The incidence of 48 individual chronic diseases was ascertained using inpatient hospital records and mortality registers. Cox proportional hazards models were used to examine the associations between each dietary score and the risk of each disease, adjusting for several potential confounders including age, sex, ethnicity, education, income, BMI, smoking status, sleep duration, physical activity levels, and a genetic risk score for longevity. The false discovery rate (FDR) was controlled to account for multiple comparisons. Further analyses included moderation and sensitivity analyses to explore potential effect modification and robustness of findings.

The study found strong inverse associations between healthy dietary patterns and the risk of numerous chronic diseases. Higher AMED scores were significantly associated with a lower risk of 32 out of 48 chronic diseases examined. These included all eight cardiometabolic disorders (CMDs), three out of ten cancers, seven out of ten psychological/neurological disorders, five out of six digestive disorders, and nine out of 14 other chronic diseases. AHEI-2010 and HPDI scores also demonstrated significant inverse associations with a substantial number of diseases (29 and 23, respectively). The AEDII score, representing an anti-inflammatory diet, was inversely associated with the risk of 14 diseases but positively associated with alcohol use disorder and psychoactive substance abuse. The AMED score consistently showed the strongest protective effect across multiple disease categories, with the most notable benefits being reductions in cardiovascular disease, several types of cancer, and a variety of neurological and psychological disorders. Analysis of AMED components highlighted that higher intakes of whole grains, vegetables, fruits, nuts, legumes, and fish, along with lower red meat intake, contributed significantly to its protective effects. Moderation analyses revealed that the strength of the associations between dietary scores and certain diseases varied across different subgroups based on factors such as age, presence of metabolic disorders, and education level. Sensitivity analyses, which excluded early-onset cases and considered participants with more dietary assessments, largely confirmed the primary findings.

This large-scale cohort study provides compelling evidence supporting the beneficial effects of healthy dietary patterns on a wide range of chronic diseases. The strong and consistent inverse associations observed across multiple disease categories highlight the importance of dietary interventions in preventing or delaying the onset of these conditions. The AMED diet stood out as particularly protective, potentially due to its rich content of anti-inflammatory and antioxidant compounds. These findings reinforce current dietary guidelines that emphasize whole grains, fruits, vegetables, legumes, nuts, fish, and reduced red/processed meat intake. The study's comprehensive approach adds to the existing literature by expanding the scope of chronic diseases examined and providing a more nuanced understanding of the relationship between specific dietary patterns and disease risk. While the study shows associations, not causality, the strong and consistent findings suggest that dietary interventions may hold substantial promise for improving public health outcomes by promoting healthy aging and preventing the development of chronic diseases.

This study's extensive analysis of four dietary patterns and their relationship with 48 chronic diseases demonstrates strong support for the adoption of healthy eating habits, particularly the AMED diet, as a crucial element in the prevention and management of multiple chronic diseases. The consistency of findings across various disease categories, coupled with the identification of key dietary components, underscores the importance of dietary guidelines that promote plant-based foods, whole grains, and unsaturated fats while limiting red and processed meats. Further research should investigate the underlying biological mechanisms that drive these associations and explore tailored dietary approaches to optimize preventative strategies.

Several limitations warrant consideration. The reliance on self-reported dietary data, inherent in the UK Biobank, introduces potential measurement error, although this is more likely to attenuate observed associations rather than exaggerate them. The observational nature of the study precludes causal inferences. The use of inpatient and mortality data may underestimate disease incidence. The predominantly Caucasian population limits the generalizability of findings to other ethnic groups. Potential reverse causality between diet and psychological conditions cannot be excluded. The inability to differentiate disease severity, as with prostate cancer and cataracts, may also impact the accuracy of the findings. Finally, adjusting for the same broad range of confounders across all diseases might not be optimal for every specific condition.