In this cross-sectional study, we investigated the relationship between adherence to MIND diet patterns and the risk of age associated poor muscle strength. Among the components of the MIND diet, green leafy vegetables, other vegetables, berries, whole grains, fish, and olive were associated with lower risk of poor HGS. Although, the brain unhealthy foods including red meat and products, fast fried foods, pastries, and sweets were associated with the risk of poor HGS. Our findings showed that adherence to the MIND diet significantly was lower risk of poor HGS and had protective effects on age related poor HGS.
Dietary patterns can play a critical role in maintaining skeletal muscle health and strength 28. In agreement with our findings, a study has shown a positive association between adherence to the Mediterranean diet (MED) and muscle strength 5. Furthermore, It has been demonstrated that older Korean men who higher intake of fruits, vegetables, potatoes, whole grains, fish (main components of MIND diet), eggs, seaweed, mushrooms, legumes had higher muscle mass compared to those belonging to a ‘Westernized’ dietary pattern 29. The MIND diet is a mainly plant-based dietary pattern, which has been designed as a combination of Mediterranean and dietary approaches to stop hypertension (DASH) dietary patterns. It has been shown that adherence to the MIND diet has been inversely associated with the risk of cognitive decline, depression, and psychological distress 15, 30. Although the MIND diet was explicitly created for prevention of cognitive decline, its dietary components may also benefit physical functional health and muscle strength.
In agreement with our findings, resent study has been reported a significant correlation between adherence to the MIND diet and HGS 31. In our study, among the components of the MIND diet, green leafy vegetable berries, whole grains, fish, and olive were associated with lower risk of poor HGS. Vegetables are rich in inorganic nitrate, and higher dietary nitrate has been associated with better physical function and HGS 32. Moreover, fish intake has been associated with HGS in older men and women 33, and n–3 fatty acids have been demonstrated beneficial effects on muscle mass and strength 34. Similarly, the higher intake of fruits as a component of the MIND diet had beneficial effects on better HGS, muscle strength, as well as FFM 5, 35.
In our study, green leafy vegetables, other vegetables, berries, whole grains, fish, and olive that are sources of folate, vitamin E, carotenoids, and flavonoids 36, were significant inversely associated with the risk of age related poor HGS. These dietary components have been shown to protect the brain through their anti-inflammatory and antioxidant properties 37, 38 and inhibition of b-amyloid deposition 39. In recent years, several studies have discussed the potential role of nutrition, nutritional supplements, and nutrients from foods in skeletal muscle health and age-related muscle loss e.g., 40, 41. However, fewer studies have examined the relationships between plant-based dietary (e.g., fruits and vegetables, grains, olive) 42, 43, and muscle health in older adults 44, 45. Moreover, the associations between bioactive compounds including curcumin, folate, and antioxidant compounds (vitamin E, carotenoids, and flavonoids) as potential factors relevant for muscle ageing are poorly understood 28. Therefore, these novel dietary candidates that acting via some mechanisms including anti-inflammatory, anti-oxidative, and anabolic-promoting functions suggested to prevent age-related muscle loss.
In the present study, plant-based and high protein dietary patterns decreased the risk of poor HGS. Nevertheless, greater adherence to the unhealthy dietary pattern was 1.49 times more at risk of poor HGS. Previous studies has been reported association between high protein intake and skeletal muscle function in the older adults 46, 47 that this agrees with our results in current study. Additionally, HGS can be influenced by intake of specific single nutrients including protein 48, which may be due to positive associations between muscle protein synthesis and dietary protein intake 49. High protein intake between 1.0–1.2 g/kg/day is appropriate for musculoskeletal health 50. Our recent finding has been demonstrated that adherence to the healthy eating index (HEI)-2015 could promote muscle strength 12. Among the HEI-2015 components, higher intake of fruit and lower adherence to added sugar had dramatically positive effects on HGS 12.
Adherence to unhealthy dietary patterns such as butter, margarine, red meat and products, fast fried foods, pastries, and sweets leads to the accumulation of free radicals and reactive oxygen and nitrogen species (ROS/NRS) by oxidative stress in several organelles in myofibres 28. Accumulation of ROS/NRS in skeletal muscle leads to impaired cellular homeostasis and damage to key cell macromolecules such as proteins, nucleic acid, and lipids, affecting their structure 51. A higher intake of beneficial foods in a healthy diet may provide not only adequate energy but also sufficient levels of relevant myo- protective nutrients and bioactive compounds 28. The interaction between the nutrients acting upon the muscle might help to preserve or improve myofibre quality and quantity by counteracting the loss of muscle strength and pathophysiology of sarcopenia 51–53. A diet rich in antioxidants such as vitamins, carotenoids, flavonoids, and minerals 41 from fruits, green leafy vegetables, berries, whole grains olive oil, and nuts such as the MED diet can help in restoring the redox homeostasis 54 in the muscle and counteract reactive ROS/NRS-induced damage 28. Therefore, plant- based diet such as the MED and MIND diets may provide the right combination of antioxidants in the amounts beneficial to redox homeostasis in the myofibrils.
This current study was the first on a large sample size to evaluate the relationship between the MIND dietary pattern and age related poor HGS among Kurdish population. However, this study suffered from some limitations. First, this is a cross- sectional study and the cause-and-effect relationship was not clear, therefore, it is not possible to infer that adherence to MIND and high protein diets decreased lower risk of poor HGS or contrariwise. Second, dietary intake was assessed by FFQ, and the error of recalling food intake should not be ignored. However, the questionnaire was presented by trained nutritionists. Nevertheless, our findings need to be confirmed in prospective studies. Therefore, further studies are recommended without these limitations.