Table 2 Validation scheme of potential food intake biomarkers for nuts

Walnuts [12, 20, 21, 28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45, 27, 46, 79, 80]

α-Linolenic acid

HMDB0001388

Plasma / serum / erythrocytes

N

U

U

U

U

U

U

Y

U

Walnuts [22, 23, 48, 47, 49, 51, 82, 81, 83]

Urolithins: urolithin A (and phase II metabolites), isourolithin A (and phase II metabolites), urolithin B (and phase II metabolites), urolithin C (and phase II metabolites)

HMDB0013695 / HMDB0029222 / HMDB0060022 /

HMDB0013696 / HMDB0041787 / HMDB0029218

Urine / plasma

N

U

Y

U

Y

U

U

Y

U

Walnuts [24, 50, 51, 81]

5-Hydroxyindole-3-acetic acid

HMDB0000763

Urine / serum

N

Y

Y

U

Y

U

U

Y

U

Almonds/hazelnuts [66,67,68,69,70,71,72]

α-Tocopherol

HMDB0001893

Plasma / serum / erythrocytes

N

U

U

U

U

U

U

Y

U

Pistachios [77]

β-Sitosterol

HMDB0000852

Serum

N

U

U

U

U

U

U

Y

U

Pistachios [76, 78]

Lutein-zeaxanthin

HMDB0003233/HMDB0002789

Plasma / serum

N

U

U

U

U

U

U

Y

U

Brazil nuts [53,54,55,56,57,58,59,60,61]

Selenium

HMDB0001349

Urine / plasma

N

Y

Y

Y

Y

U

U

Y

U