The Spanish study analysed the effects of dietary changes on WAT of obese females and found a correlation between significant reductions in circulating inflammatory markers and low-density lipoprotein (LDL) cholesterol levels in the WAT.
“Thus, higher adherence to the traditional MD is associated with transitions to healthier obese phenotypes and inversely related to long-term complications of diabetes and several cardiovascular risk factors,” the researchers write in Nutrients.
In addition, MDSA favoured an abundance of small adipocytes and anti-inflammatory macrophages in WAT and stimulated mitigating gene synthesis in subcutaneous (SAT) and visceral (VAT) adipose tissue (including angiogenesis, adipogenesis, and autophagy). This suggests “potential mechanistic links between MD-induced improvements on WAT biology and the proven systemic benefits of this dietary pattern”, the authors say.
There is extensive clinical evidence on the benefits of the Mediterranean diet (MD) and its association with reduced type 2 diabetes, cardiovascular disease and improved lipid profile, blood pressure and systemic inflammation.
Equally, almonds are rich in monounsaturated fat, fibre, and polyphenols (including bioavailable tannins and flavonoid) that reduce inflammation and oxidative stress and contain the fat-soluble antioxidant vitamin, α-tocopherol, with known protective effects on obesity, metabolic syndrome, and lipid levels.
Consequently, dietary interventions are widely advocated as an important component of CVD prevention since “switching to MD can be more attainable than pursuing weightloss”.
They said: “MD supplemented with tree nuts, which are important components of the MD, has demonstrated a better performance in lowering blood atherogenicity, the prevalence of metabolic syndrome and the cumulative incidence of stroke versus MD supplemented with extra-virgin olive oil.”
However, despite the proven benefits of MD and almonds the precise mechanisms mediating these effects are not entirely understood.
The current investigation focused on the short-term effects of an MD-based diet supplemented with almonds on the main characteristics of WAT dysfunction and the association between tissue variables and systemic markers of metabolic health in severely obese women that were bariatric surgery (BS) candidates.
Female participants (38) were randomly assigned to a three-month intervention with MDSA or continued their normal dietary pattern. SAT and VAT biopsies were obtained at baseline, following an eight-hour fasting period, and again at the end of the study.
There were no changes in body weight or insulin resistance for either group, but total cholesterol and LDL-cholesterol levels decreased in the MDSA group over the study period.
Researchers also noted changes in the WAT biology (particularly in the VAT) of the intervention group, including increased anti-inflammatory macrophage infiltration.
“Activated M2-like macrophages play a role in WAT expansion, thermoregulation, antigen presentation and iron homeostasis, secreting anti-inflammatory cytokines.”
Increased gene expression
The MDSA group exhibited raised α-Linolenic acid (ALA) relative content in red blood cell membranes and ‘beiging’ - the process that transforms WAT into brown-like adipose tissue known as beige/brite adipose tissue, which is more efficient at releasing energy.
The authors comment: “Previous studies have focused on the ability of specific dietary components, such as polyphenols, in enhancing energy expenditure by activating brown adipose tissue or promoting WAT beiging.”
While average SAT and VAT adipocyte regions did not significantly change in either group, an analysis of adipocyte size distribution revealed MDSA favoured the abundance of small adipocytes in SAT and VAT showed increased smaller adipocytes in the MDSA group, compared to controls.
Overall, MDSA increased gene expression and promoted upregulation of fatty acid thermogenesis, suggesting it reduces oxidative stress and enhances VAT tissue health.
Published online: https://doi.org/10.3390/nu14132617
‘Positive Effects of a Mediterranean Diet Supplemented with Almonds on Female Adipose Tissue Biology in Severe Obesity’
Óscar Osorio-Conles et al.