Green Mediterranean diet may be protective against age-related brain atrophy, finds study

A Green-MED, high-polyphenol diet rich in Mankai, green tea, and walnuts and low in red/processed meat has been demonstrated in a new study to be possibly neuroprotective for age-related brain atrophy. This study was conducted by Alon Kaplan and team, results of which were published in the American Journal of Clinical Nutrition on 11th January, 2022.

Dietary effects on age-related brain shrinkage are mainly unknown. The researchers set out to investigate the effect of a Mediterranean diet high in polyphenols and low in red/processed meat (Green-MED diet) on age-related brain shrinkage.

This 18-month clinical experiment used magnetic-resonance imaging to quantify brain structure volumes longitudinally utilizing hippocampus occupancy (HOC) and lateral-ventricle-volume (LVV) expansion scores as neurodegenerative indicators. Participants with abdominal obesity/dyslipidemia were randomly allocated to one of three diets: (1) healthy dietary guidelines (HDG), (2) Mediterranean (MED), or (3) Green-MED (MED diet higher in polyphenols and lower in red/processed meat). All subjects were given free gym memberships as well as physical exercise advice. Both MED groups consumed 28g of walnuts each day (+440 mg of polyphenols per day). Green-tea (3-4 cups/day) and Mankai (Wolffia-globosa strain, 100g frozen cubes/day) green shake (+800mg polyphenols/day) were ingested by the Green-MED group.

The key findings of this study were as follow:

1. 224 (79 percent) of 284 individuals (age = 51 years; 88% men; BMI = 31.2kg/m2; apolipoprotein E4 genotype = 15.7%) completed the experiment with eligible whole-brain MRIs.

2. The pallidum (-4.2%), third ventricle (+3.9%), and LVV (+2.2%) showed the greatest volume changes. When compared to younger individuals, those over the age of 50 saw faster atrophy.

3. In patients 50 years old, HOC decrease and LVV expansion were reduced in both MED groups, with Green-MED diet participants having the greatest outcomes when compared to HDG.

4. Younger participants exhibited similar tendencies. Improved insulin sensitivity during the course of the experiment was the greatest predictor of brain atrophy attenuation (p0.05).

5. Higher intakes of Mankai, green tea, and walnuts, as well as lower intakes of red and processed meat, were substantially and independently linked with lower HOC reduction.

6. Urinary levels of the Mankai-derived polyphenols urolithin-A and tyrosol were shown to be strongly related to decreased HOC decline.

In conclusion, The positive relationship between the green Mediterranean diet and age-related neurodegeneration may be explained in part by the amount of polyphenols in plant-based food sources, which include antioxidant and anti-inflammatory compounds.

Reference:

Kaplan, A., Zelicha, H., Meir, A. Y., Rinott, E., Tsaban, G., Levakov, G., Prager, O., Salti, M., Yovell, Y., Ofer, J., Huhn, S., Beyer, F., Witte, V., Villringer, A., Meiran, N., Emesh, T. B., Kovacs, P., von Bergen, M., Ceglarek, U., … Shai, I. (2022). The effect of a high-polyphenol Mediterranean diet (GREEN-MED) combined with physical activity on age-related brain atrophy: the DIRECT PLUS randomized controlled trial. In The American Journal of Clinical Nutrition. Oxford University Press (OUP). https://doi.org/10.1093/ajcn/nqac001