The Effects of Nitrate on Brown Fat Fraction and Activation in Older Adults With Type 2 Diabetes: A Randomised, Double-Blind and Placebo-Controlled Crossover Trial.

Beetroot juice supplementation significantly increased venous plasma nitrate and nitrite concentrations compared to placebo.

• Plasma nitrate and nitrite concentrations were significantly elevated following BJ versus placebo (p < 0.001)
• The beetroot juice contained approximately 12.4 mmol/L inorganic nitrate, while the placebo contained approximately 0.1 mmol/L
• Participants consumed 140 mL/day for 14 days, confirming successful supplementation compliance and absorption

Nitrate supplementation did not affect brown adipose tissue fat fraction in older adults with type 2 diabetes.

• BAT fat fraction was not significantly different between beetroot juice and placebo conditions (p = 0.650)
• Thirteen older adults with T2DM participated (HbA1c: 58 ± 13 mmol·mol-1; BMI: 29.1 ± 3.1 kg·m-2)
• MRI was used to image supraclavicular BAT following a rested cooling protocol
• The study was a double-blind, randomised, balanced, placebo-controlled crossover design

Nitrate supplementation did not affect brown adipose tissue activation in older adults with type 2 diabetes.

• BAT activation was not significantly different between beetroot juice and placebo conditions (p = 0.152)
• Infrared thermography (IRT) was used to assess supraclavicular BAT activation
• BAT activation was assessed following a 60-minute cold water perfused jacket cooling protocol (8.1 ± 1.2°C)

The cooling protocol successfully reduced mean skin temperature without inducing shivering in either condition.

• Cooling significantly reduced mean skin temperature in both BJ (-0.8 ± 0.7°C) and placebo (-0.6 ± 0.6°C) conditions (p < 0.001)
• Respiratory exchange ratio remained representative of nonshivering thermogenesis throughout the cooling protocol (RER: 0.88 ± 0.05 a.u.)
• Both respiratory parameters and mean skin temperature were measured during the cooling protocol to confirm participants were not shivering

The study was designed to test whether inorganic nitrate supplementation could alter brown adipose tissue in humans, motivated by rat studies showing white-to-brown adipose tissue conversion.

• Treatments that alter white adipose tissue to express a metabolically active brown adipose phenotype in rats may offer adjunct treatment in people with T2DM
• Type 2 diabetes mellitus is characterised by chronic hyperglycaemia, and obesity is a major risk factor increasing morbidity and mortality
• The crossover design allowed each participant to serve as their own control across both 14-day supplementation periods