March 7, 2014
Yesterday we wrote about an experiment done in the 1990s in which a supplement containing 50 mg thiamine – alias vitamin B1 – improved the mood of the student subjects. In 2012 Chinese epidemiologists published a study with similar results to those of the experiment done in the nineties. The Chinese suggest that a diet containing relatively large amounts of thiamine reduces the likelihood of depression.
A few days ago we wrote about an experiment done in the 1990s in which a supplement containing 50 mg thiamine – alias vitamin B1 – improved the mood of the student subjects. In 2012 Chinese epidemiologists published a study with similar results to those of the experiment done in the nineties. The Chinese suggest that a diet containing relatively large amounts of thiamine reduces the likelihood of depression.
The researchers, who worked at the Shanghai Institutes for Biological Sciences, studied 1587 men and women aged between 50 and 70. The researchers used questionnaires to determine whether the participants had depressive tendencies.
The researchers also measured the amount of thiamine the participants ingested through their diet, and analysed the composition of the participants’ red blood cells. They looked not only at the concentration of free thiamine, but also at that of thiamine monophosphate and thiamine diphosphate. The latter in particular plays a key role in depression: it’s a co-factor for the production of serotonin.
The researchers divided the participants into four equal-sized quartiles according to their blood levels and the amount of dietary thiamine they ingested. In the figures below the values for thiamine intake and status are lowest for quartile 1 and highest for quartile 4.
The researchers fixed the likelihood of depression in the participants with the highest thiamine intake [Q4] at 1. The figure below shows that the participants with the lowest thiamine intake were one and a half times more likely to suffer from depression.
The relationship was not statistically significant, though. This is probably because the level of thiamine intake doesn’t actually tell us that much.
The body uses most of the thiamine it ingests – in the form of thiamine diphosphate – to convert glucose into energy. That means that you really need to look at the relationship between thiamine intake and carbohydrate intake. When the Chinese did this, they discovered that, among the participants, a high carbohydrate intake coincided with a high thiamine intake. That’s why they couldn’t see a relationship between thiamine intake and likelihood of depression.
The figures below are more revealing. The subjects in the quartile with the lowest concentrations of free thiamine, thiamine monophosphate and thiamine diphosphate in their red blood cells were 3, 3.5 and 2 times respectively more likely to be depressed than those in the quartile with the highest concentration. And yes, the relationships were statistically significant.
The relationship was not statistically significant, though. This is probably because the level of thiamine intake doesn’t actually tell us that much.
The body uses most of the thiamine it ingests – in the form of thiamine diphosphate – to convert glucose into energy. That means that you really need to look at the relationship between thiamine intake and carbohydrate intake. When the Chinese did this, they discovered that, among the participants, a high carbohydrate intake coincided with a high thiamine intake. That’s why they couldn’t see a relationship between thiamine intake and likelihood of depression.
The figures below are more revealing. The subjects in the quartile with the lowest concentrations of free thiamine, thiamine monophosphate and thiamine diphosphate in their red blood cells were 3, 3.5 and 2 times respectively more likely to be depressed than those in the quartile with the highest concentration. And yes, the relationships were statistically significant.
Going by the results of this study you’d expect that taking thiamine supplements would reduce the likelihood of depression. But there were too few supplement users among the participants to be able to say whether this was indeed the case.
“This population-based analysis suggests an association between thiamine malnutrition and depressive symptoms among older Chinese adults”, is the researchers’ careful formulation. “This finding warrants further investigation in prospective studies.”
Thiamine nutritional status and depressive symptoms are inversely associated among older Chinese adults.
Zhang G1, Ding H, Chen H, Ye X, Li H, Lin X, Ke Z.
Abstract
Thiamine has been hypothesized to play an important role in mental health; however, few studies have investigated the association between thiamine nutritional status and depression in the general population. Concentrations of free thiamine and its phosphate esters [thiamine monophosphate (TMP) and thiamine diphosphate (TDP)] in erythrocytes were measured by HPLC among 1587 Chinese men and women aged 50-70 y. The presence of depressive symptoms was defined as a Center for Epidemiological Studies Depression Scale score of ?16. The median erythrocyte concentration (nmol/L) was 3.73 for free thiamine, 3.74 for TMP, and 169 for TDP. The overall prevalence of depressive symptoms was 11.3%. Lower concentrations of all 3 erythrocyte thiamine biomarkers were monotonically associated with a higher prevalence of depressive symptoms: the multivariable adjusted ORs comparing the lowest with the highest quartiles were 2.97 (95% CI = 1.87, 4.72; P-trend < 0.001) for free thiamine, 3.46 (95% CI = 1.99, 6.02; P-trend < 0.001) for TMP, and 1.98 (95% CI = 1.22, 3.21; P-trend = 0.002) for TDP. In conclusion, poorer thiamine nutritional status and higher odds of depressive symptoms were associated among older Chinese adults. This finding should be further investigated in prospective or interventional studies.
PMID: 23173173 [PubMed - indexed for MEDLINE] PMCID: PMC3521461
