In the September 2016 issue of the journal Andrologica, a team of researchers published a study that concluded:
[V]itamin B12 concentrations in the blood were significantly lower in patients with PE than the subjects without PE (p < .0001)…. Moreover, the vitamin B12 levels correlated positively with [intravaginal ejaculation latency time] IELT values and correlated negatively with [premature ejaculation diagnostic tool] PEDT scores. This work has also demonstrated that plasma vitamin B12 levels in patients with PE showed an increasing trend with decreasing PE severity.
On October 7, 2016, The Daily Mail inexplicably decided to use this study to advance a pro-Marmite agenda:
[S]ales of Marmite may be in for a boost after scientists discovered it could hold the secret to making men last longer in the bedroom.
New research suggests a diet rich in daily helpings of vitamin B12 can combat premature ejaculation, a problem which affects one in four men in the UK.
And Marmite is one of the richest sources of the vitamin – along with meat, fish, eggs and fortified breakfast cereals.
The connection they made sounds — and may be — reasonable, but it relies on the untested assumption that increasing B12 would reduce premature ejaculation. Correlation, after all, does not necessarily equal causation, as the authors of the study state:
It is not yet known whether this finding could be translated into a solution for PE; however, vitamin B12 supplementation for the treatment of PE merits further evaluation.
The Daily Mail claim also relies on the assumption that all PE is caused by the same factor, a notion that is not supported by current research:
The pathophysiology of premature ejaculation appears to be multifactorial, implicating the need for multimodal therapeutic regimens to successfully treat premature ejaculation. Multiple treatment regimens have been shown to be effective in extending the time between penetration and ejaculation.
Still, Marmite is fortified with vitamin B12, and it contains 25% of the recommended daily intake of the vitamin. Meat, however, is a much more plentiful source of B12. Because Marmite is completely vegetarian, however, it is a good option for those who do not eat meat.
If you want to get your B12 from a source that is not Marmite or meat, have no fear! Many breakfast cereals are fortified with 25% of your daily intake of the vitamin, too.