Based on research by Dr. Derrick Lonsdale, MD
***Look for a post on how to supplement with B1 soon***
You eat every day. You probably even eat a lot. But what if eating plenty of calories doesn’t mean your body is getting what it actually needs to function? That’s the uncomfortable truth behind a growing area of research — and it starts with a tiny but mighty nutrient called thiamine, also known as vitamin B1.
What Is Thiamine, and Why Does It Matter?
Think of thiamine as the spark plug in a car engine. Without it, the engine has all the fuel in the world — but it won’t start. Thiamine is the nutrient your cells use to convert food into real, usable energy. It sits at critical points in your metabolism, helping run key enzymes that power your mitochondria — the “batteries” inside every cell.
When those enzymes don’t get enough thiamine, your cells can’t use oxygen properly. Scientists call this pseudohypoxia — it’s like your cells are suffocating even though there’s plenty of air. The result? Widespread fatigue, brain fog, and a long list of symptoms that are hard to trace back to one cause.
Why So Many People May Be Low — Without Knowing It
Here’s the tricky part: you don’t have to be malnourished in the traditional sense to be thiamine-deficient. Research shows that 20–50% of psychiatric and elderly patients show signs of insufficiency, and plasma thiamine levels in diabetics can be up to 76% lower than in healthy individuals.¹
The late Dr. Derrick Lonsdale, a pediatrician and nutritional medicine pioneer who lived to age 100, called this pattern “high-calorie malnutrition.” He argued that a diet packed with processed foods, refined carbs, and sugar could drain the body of thiamine — because the more carbohydrates you eat, the more thiamine your body needs to process them. It’s a bit like hiring a hundred workers but only paying five of them. The system breaks down fast.
Ultra-processed foods now make up 50–60% of daily calories in some high-income countries² — and they come stripped of the very micronutrients, including thiamine, needed to metabolize them. Common medications like metformin, diuretics, and omeprazole can also reduce thiamine levels. Chronic stress, gut issues, and even certain foods like raw fish and coffee act as thiamine “blockers.”
The Symptoms Look Like Everything Else
This is what makes thiamine insufficiency so hard to spot. A 1940 study on experimental deficiency in humans found that classic beriberi symptoms were nearly absent for 88 days — but during that time, participants experienced fatigue, irregular heartbeat, mood changes, digestive problems, temperature dysregulation, and poor concentration. Sound familiar? These symptoms match dozens of modern diagnoses, from anxiety to IBS to chronic fatigue syndrome.
Dr. Lonsdale pointed out that the brain becomes “hyper-irritable” when it’s running low on energy, which can trigger exaggerated stress responses and what we now call dysautonomia — dysfunction of the nervous system that controls heart rate, digestion, and temperature.
Beyond Basic Deficiency: A New Way of Thinking
What makes this research exciting is the idea that thiamine isn’t just a vitamin to prevent a disease — it may act as a metabolic activator at higher doses. Studies suggest that conditions like Alzheimer’s, Parkinson’s disease, and ALS all show reduced activity of thiamine-dependent enzymes in the brain.³ In some cases, high-dose thiamine therapy produced remarkable improvements, even in patients without a classic deficiency.
Thiamine may be one of the most underestimated tools in the health conversation today. If you’re dealing with unexplained fatigue, brain fog, gut problems, or mood issues — it may be worth asking your doctor about your B1 status.
Check out the research writings of Dr. Lonsdale here.
Want to Learn More?
→ The Link Between Processed Food and Micronutrient Depletion — A comprehensive overview of thiamine deficiency and its modern drivers (NIH)
→ Thiamine and the Nervous System: What the Research Shows — Clinical review published in Postgraduate Medical Journal (2023)
References
¹ Wiley KD, Gupta M. Vitamin B1 (Thiamine) Deficiency. StatPearls [Internet]. StatPearls Publishing; 2024. PMID: 30725889.PubMed
² Schostak T, San Millan I, Jani A, Johnson RJ. Thiamine deficiency: a commonly unrecognised but easily treatable condition. Postgrad Med J. 2023 Aug;99(1174):844–848. PMID: 37125640.PubMed
³ Wiley KD, Singh J. Vitamin B1 (Thiamine) Deficiency. StatPearls [Internet]. Updated 2024 Jan 31.PubMed
