Colorectal cancer is the main leading cause of death from cancer worldwide. Protective effects of vitamin B1 on colorectal cancer have been observed in some epidemiological studies. A systematic review and meta-analysis of observational studies evaluated the association of intake of vitamin B1 with the incidence of colorectal cancer. Relevant studies were identified in MEDLINE via PubMed (published up to September 2020). We extracted data from articles on vitamin B1 and used a multivariable-adjusted odds ratio (OR) and a random-effects model for analysis. We found seven articles meeting the inclusion criteria (1 of cohort studies and 6 case-control studies) and a total of 6,184 colorectal cancer cases were included in this meta-analysis. The multivariable-adjusted OR for pooled studies for the association of roughly the same high dose level versus the lowest vitamin B1 intake and the risk of colorectal cancer was 0.76 (95% confidence interval ([95%CI]: 0.65, 0.89). This meta-analysis studied the relationship between vitamin B1 and colorectal cancer. We found vitamin B1 intake was inversely associated with the risk of colorectal cancer. However, further research and large sample studies need to be conducted to better validate the result.

Like fungi and some prokaryotes, plants use a thiazole synthase (THI4) to make the thiazole precursor of thiamin. Fungal THI4s are suicide enzymes that destroy an essential active-site Cys residue to obtain the sulfur atom needed for thiazole formation. In contrast, certain prokaryotic THI4s have no active-site Cys, use sulfide as sulfur donor, and are truly catalytic. The presence of a conserved active-site Cys in plant THI4s and other indirect evidence implies that they are suicidal. To confirm this, we complemented the Arabidopsistz-1 mutant, which lacks THI4 activity, with a His-tagged Arabidopsis THI4 construct. LC-MS analysis of tryptic peptides of the THI4 extracted from leaves showed that the active-site Cys was predominantly in desulfurated form, consistent with THI4 having a suicide mechanism in planta. Unexpectedly, transcriptome data mining and deep proteome profiling showed that barley, wheat, and oat have both a widely expressed canonical THI4 with an active-site Cys, and a THI4-like paralog (non-Cys THI4) that has no active-site Cys and is the major type of THI4 in developing grains. Transcriptomic evidence also indicated that barley, wheat, and oat grains synthesize thiamin de novo, implying that their non-Cys THI4s synthesize thiazole. Structure modeling supported this inference, as did demonstration that non-Cys THI4s have significant capacity to complement thiazole auxotrophy in Escherichia coli. There is thus a prima facie case that non-Cys cereal THI4s, like their prokaryotic counterparts, are catalytic thiazole synthases. Bioenergetic calculations show that, relative to suicide THI4s, such enzymes could save substantial energy during the grain-filling period.

Thiamin, riboflavin and pyridoxal phosphate (PLP) concentrations are useful indices for evaluating vitamin B1, B2 and B6 status. Several HPLC assays have been developed for determining thiamin, riboflavin and PLP in biological matrix. However, no existing LC-MS/MS methods can be used to quantify thiamin, riboflavin and PLP in dried blood spots (DBSs), which are often used as a sampling/storage vessel for blood from infants and children. This study evaluated the validity, reliability and stability of an LC-MS/MS assay for measuring thiamin, riboflavin and PLP in DBS cards. DBS samples were deproteinized by adding trichloroacetic acid containing thiamine-[13C4], riboflavin-[13C4,15N2] and pyridoxal-d3 as internal standards. Thiamin, riboflavin and PLP were separated on a C8 column with a 5-min run time. Both the between-run and within-run variable coefficients (CV% values) were < 8.56%. The accuracies were good and showed relative errors (RE% values) from -7.40% to 3.12%. The lower limits of quantification (LLOQs) ranged from 0.2 to 0.5 ng/mL, and the recoveries were from 81.49% to 112.23% for all 3 analytes. The matrix effects (ME% values) were acceptable, and the CV% values of the internal standard-normalized matrix factors were <15% (n = 6). Thiamin, riboflavin and PLP were stable on the DBS card during at least 15 days of room-temperature storage under vacuum in the dark, and the measurements of thiamin, riboflavin and PLP in the DBSs showed good agreement with the corresponding concentrations determined from liquid blood (R2 values >0.96). The validated method was successfully applied to the nutritional assessment of vitamins B1, B2, and B6 in 48 Chinese children.

OBJECTIVE: The thiamin is often used in the treatment of neuropathy, and pregabalin is often used to treat neuropathic pain. Our study examined the influence of thiamin on the efficacy of pregabalin in a rat model of spinal nerve ligation (SNL)-induced neuropathic pain.
METHODS: Sprague-Dawley male rats were randomly divided into six groups. The neuropathic pain-relieving properties were measured by plantar test, cold plate test, and hot plate test after administration of pregabalin (i.v) and/or thiamin (i.p) in SNL rats 14 days after operation.
RESULTS: In the therapy period, pregabalin, or thiamin alone all produced antinociceptive effects in rats with neuropathic pain. And combination treatment of thiamin and pregabalin resulted in an enhanced pain relief compared to the administration of pregabalin or thiamin alone.
CONCLUSIONS: Combination of thiamin and pregabalin produces an additive antinociceptive effect in neuropathic pain rats, this drug combination may offer a beneficial treatment option for neuropathic pain.

The derivatization of thiamin vitamers to their respective thiochrome by ferricyanide to facilitate fluorescence detection following separation by HPLC provides a powerful analytical tool. However the polyphenolic compounds in red wine readily interact with ferricyanide, reducing the effectiveness of ferricyanide oxidation in the derivatization of thiamin. We describe a method to facilitate the removal of polyphenolic compounds that interfere with the ferricyanide derivatization of thiamin. Polyvinylpolypyrrolidone afforded the total removal of phenolic compounds from red wines and allowed a spike recovery of thiamin vitamers (101% for thiamin; 104% for TMP; and 100% for TDP) in a wide range of red wines. This research found that Merlot styles of red wine contained the highest concentration of total thiamin (29.01 ng/mL) while Pinot Noir wines contained the lowest total concentration (8.27 ng/mL).