Table 2 Measurement of deficiencies in the included studies

Figueroa 1953 [17]

Fasting Hour Excretion of B1 and B2

B1 = < 0.6 microgram./hr; B2 = 20 μ/hr

Photofluorometery: B1 = Hennesey and Cerecedo’s technique; B2 = Connor and Straub’s method.

Darnton-Hill 1986 [13]

TPP effect and TK activity for B1; blood levels of: B6; B9; B12; C; albumin a

TPP effect for B1= > 14% activity; TK activity for B1 = < 130 μmol/min/L; B6 = < 300 μmol/min/L;P5P for B6= > 50% activity; B12 = <150pmol/L; Iron = <10 μmol/L; C = < 23 μmol/L; serum B9 = <4 ng/ml

B1 = measuring colorimetrically the formation of sedoheptulose-7-phosphate with ribose-5- phosphate as the substrate; B6 = erythrocyte transaminase and pryidoxal5 phosphate activation. B9 and B12 = isotopic radioassay; C = colorimetric procedure using dinitrophenylhydrazine.

van der Westhuyzen 1987 [22]

Blood levels of: B6; B9; B12; albumin; erythrocyte level of B1

Reference ranges determined in healthy subjects: B6 = 26–96 nmol/; B1 = 50–106 microgram/liter; B12 = 160–900 ng/l; serum folate = 2–13microgram/liter; serum I'-glutamyltransferase (GGT) = 10–50 U/I.

Radio-assay kit; Biochromatic Analyzer commercial kits; For B1 = automated microbiological assay using a streptomycin-resistant mutant of Lactobacillus fermenci as the test organism.

Drijver 1993 [16]

TDP effect and TK activity for B1; Blood levels of: B6; B12

TDP effect reference range = 0–25%; TK activity reference range = 10.4–15.1 U/mmol Hb; PLP effect reference range = 35–107 nmol/l;

HPLC; PLP measured with a fluorimeter

Kertesz 2001 [24]

Levels NR. Results of the following were found normal: B12; B 9; iron

NR

Hospital tests

Malmauret 2002 [21]

Blood levels of vitamins: A; B1; B6; B9; B12; C; E

B6 = 23–100 nmol/l; B12 = 160–420 pmol/l; B1 = 6–40 mmol/l.

HPLC and radioimmunoassay

Fung 2005 [23]

Anaemia, albumin level

NR

NR

Kubisova 2008 [18]

Blood levels of: prealbumin; albumin; haemoglobin

Albumin <33 g/l; prealbumin <0.16 g/l.

NR

Lee 2014 [20]

Blood levels of: B1; B6; B12; C; haemoglobin

Reference ranges for vitamins: B1 = 59 to 213; B12 = 200 to 950; B6 = 20 to 202; C = 26.1 to 84.6

Vitamin B1, B6, and C = HPLC; B12 levels = electro-chemiluminescence immunoassay