Don’t let a conventional doctor dismiss your questions about B vitamins and your fatigue, not after reading this study from Japan. While there are literally hundreds of medical reasons for someone to feel tired, studies like this suggest that we should keep B12 and Folate in that list rather than just blame a stressful lifestyle or poor sleep. We will continue to consider this possibility in our patients, along with the rest of a list mostly ignored by mainstream medicine.
We don’t need a study to remind us that life seems to be causing far more fatigue in ourselves and others around us. It is true that longer work hours, less sleep, more tasks to get done (despite the promises of technology lessening our workload), and other factors can make us tired, but fatigue is not always that simple.
In our clinic we differentiate appropriate fatigue from inappropriate fatigue. If you just finished a 10-12 hour shift, stayed up too late on the weekend, or are going through life stress of unusual proportions, yes, you will feel tired. However, you will mostly be able to push through, function as needed, and ‘get over’ this appropriate fatigue. Inappropriate fatigue comes into play when you can’t identify a reason or trigger, when you can’t function normally for a longer time, and when it just does not go away with rest or slowing down.
That is when you should start looking for other reasons besides life in general or bad habits. This study suggests that B12 and folate levels should be on the list of problems to consider. These two vitamins play a role in the methylation cycle which then plays a role in neurotransmitters, cell membrane health, muscle energy, detoxification, hormonal balance, and more. It should be no surprise that deficiencies could lead to noticeable symptoms.
The Japanese study behind this report was a simple design and does not mean that every tired person has low vitamins nor that taking a B vitamin will solve all your problems. It surveyed 600 individuals comparing their reports of fatigue and other variables to their levels of B12, folate, and homocysteine (a marker of B12/folate sufficiency). They found significant correlations between these markers and reports of fatigue.
Again, without going too far in blaming all fatigue on these vitamins, to help fatigued patients restore healthier, more abundant lives, medical providers should either check vitamin levels, suggest a B vitamin supplement, or review their patient’s nutritional habits. Using the correct labs for B vitamins and choosing the right forms of B vitamins preferred in functional medicine doctors could lead to more energy not only in Japan but worldwide.
Get started with Sanctuary today!
Click below to schedule your first conversation with our Patient Support Team.
Original Article:
Hiroaki Kanouchi, Ayaka Yamamoto, Akiko Kuwabara, Shigeo Takenaka, Eiji Nishikubo, Yukihiro Nomura, Takehiro Naruto, Kyosuke Watanabe, Kei Mizuno, Yasuyoshi Watanabe. Associations of Plasma Homocysteine Reflecting Vitamin B12 and Folate Status with Fatigue-Related Outcomes in Healthy Adults. Nutrients, 2026; 18 (6): 941 DOI: 10.3390/nu18060941
Thanks to Science Daily:
Osaka Metropolitan University. “Vitamin B12 and folate deficiencies linked to chronic fatigue.” ScienceDaily. ScienceDaily, 28 May 2026. <www.sciencedaily.com/releases/2026/05/260528082501.htm>.
Sanctuary Functional Medicine, under the direction of Dr Eric Potter, IFMCP MD, provides functional medicine services to Nashville, Middle Tennessee and beyond. We frequently treat patients from Kentucky, Alabama, Mississippi, Georgia, Ohio, Indiana, and more... offering the hope of healthier more abundant lives to those with chronic illness.
Dr. Eric Potter graduated from Vanderbilt Medical School and then went on to specialize in internal medicine (adult) and pediatric care, spending significant time and effort in growing his medical understanding while caring for patients from all walks of life.
