Vitamin B1 (Thiamine HCL)

What is Thiamine?

B1 Thiamine is an essential nutrient found in small doses in food, fortified in bread and cereal products (12), and taken as a supplement. Only small amounts are stored by the liver which means we need to source it from our daily diet (17). It was the first B vitamin to be discovered, which is why we call it B1.

Why Do Outdoor Adventurers Need Thiamine?

Thiamine plays an essential role in the supply of energy to our tissues and in the breakdown of macronutrients for energy (10). It plays a crucial role in carbohydrate metabolism and works alongside other B vitamins to support energy production, nerve function, and muscle activity. 

Importantly, insufficient intake of thiamine due to poor diet can lead to deficiency symptoms in as little as 18 days (19). Deficiency can impair physical performance and increase fatigue (21).

Fortunately, research has found that supplementing with thiamine can decrease perceived exhaustion (5) – very handy on the trail! 

Large daily energy expenditure creates inflammation and generates oxidative stress – both of which deplete our minimal thiamine reserves and increase the need to supplement our dietary intake when more active than normal (20). 

Dietary Sources of Thiamine?

Thiamine is present in small amounts in common foods like orange juice, milk, corn, chicken, and apples (11). While getting enough off-trail is easy, maintaining intake on-trail is more challenging.

What’s the Best Form of Thiamine For Hikers?

Thiamine comes in many forms. Some are fat soluble, like Benfotiamine. This means it needs to be converted in the body to thiamine (3) and requires ingestion of dietary fats simultaneously for optimum bioavailability. Fat-soluble forms can also build up in fat tissue in the body causing toxicity risk (though this is very rare) and are mostly used to treat extreme cases of thiamine deficiency in a hospital setting. 

In contrast, water-soluble forms of thiamine are rapidly absorbed by the small intestine, don’t need dietary fats for absorption, and are available for energy use immediately. They have been widely studied and have high bioavailability across varied diets. As excess is excreted quickly there is next to no toxicity risk. 

Thiamine Mononitrate is the form most commonly used in fortified foods like bread and cereals however its absorption is quite slow. Thiamine Pyrophosphate is an active form of thiamine which means it’s ready for immediate use in the body, but unfortunately, this means it degrades quickly and is unsuitable for use in supplementation. 

Thiamine Hydrochloride is the gold standard when it comes to supplementation because it’s well-absorbed, well-researched, widely available, and stable. 

Key Information About Thiamine

Deficiency Stats

Thanks to fortified bread in Australia and the US, most people meet their daily thiamine needs while going about their normal routine at home.

However, the latest Australian Bureau of Statistics survey found 7% of males and 16% of females are deficient (1), while in the US, 6% of adults fall short (14).

Why Optiventure Has 3mg of Vitamin B1 – Thiamin Hydrochloride

The optimal intake of thiamine remains uncertain, and while no upper limit has been established, doses of at least 3mg have been used long-term without adverse effects (13). In fact, side effects only occur at extremely high doses above 700mg (8).

Although the RDI is set at 1.2mg for men and 1.1mg for women, evidence suggests that individuals engaged in strenuous activity or endurance sports may benefit from higher intake due to increased energy demands and nutrient turnover (10). Hikers and adventurers fit into this category. With no risk of adverse effects and an improved likelihood of improved performance, we supplied 250% (men) and 272% (women) of your daily intake requirements.

Research shows that the body can absorb only 4.8 – 8.3mg of thiamine from a single dose, meaning larger amounts provide no extra benefit – excess is simply excreted (11,14,15). Additionally, studies indicate that thiamine loss in urine is minimal above 2.5mg, while absorption declines sharply beyond 5mg (9,11). 

This makes 3mg the ideal choice – it offers well above the RDI while ensuring efficient uptake, and space for natural dietary intake without unnecessary waste. 

References

1. Australian Bureau of Statistics. (2015, March 6). Australian health survey: Usual nutrient intakes, 2011-12. Retrieved February 25, 2025, fromhttps://www.abs.gov.au/statistics/health/health-conditions-and-risks/australian-health-survey-usual-nutrient-intakes/latest-release
2. Agabio, R. (2005). Thiamine administration in alcohol-dependent patients. Alcohol and Alcoholism, 40(2), 155–156.
3. Aguilar, F., Charrondiere, U. R., Dusemund, B., Galtier, P., Gilbert, J., Gott, D. M., et al. (2008). Benfotiamine, thiamine monophosphate chloride, and thiamine pyrophosphate chloride, as sources of vitamin B1 added for nutritional purposes to food supplements: Scientific opinion of the panel on food additives and nutrient sources added to food (ANS). EFSA Journal, 864, 1–31.
4. Bettendorff, L. (2012). Thiamin. In J. W. Erdman, I. A. Macdonald, & S. H. Zeisel (Eds.), Present knowledge in nutrition (10th ed., pp. 261–279). Wiley-Blackwell.
5. Choi, S. K., Baek, S. H., & Choi, S. W. (2013). The effects of endurance training and thiamine supplementation on anti-fatigue during exercise. Journal of Exercise Nutrition & Biochemistry, 17(4), 189–198. https://doi.org/10.5717/jenb.2013.17.4.189
6. Institute of Medicine, Food and Nutrition Board. (1998). Dietary reference intakes: Thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. National Academy Press.
7. Levy, G., & Hewitt, R. R. (1971). Evidence in man for different specialised intestinal transport mechanisms for riboflavin and thiamin. The American Journal of Clinical Nutrition, 24, 401–404.
8. Meador, K., Loring, D., Nichols, M., Zamrini, E., Rivner, M., Posas, H., Thompson, E., & Moore, E. (1993). Preliminary findings of high-dose thiamine in dementia of Alzheimer’s type. Journal of Geriatric Psychiatry and Neurology, 6(4), 222–229. https://doi.org/10.1177/089198879300600408
9. Morrison, A. B., & Campbell, J. A. (1960). Vitamin absorption studies. I. Factors influencing the excretion of oral test doses of thiamine and riboflavin by human subjects. The Journal of Nutrition, 72(4), 435–440. https://doi.org/10.1093/jn/72.4.435
10. National Health and Medical Research Council. (n.d.). Thiamin. Eat For Health. Retrieved February 25, 2025, fromhttps://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/thiamin
11. Office of Dietary Supplements. (n.d.). Thiamin - Health professional fact sheet. National Institutes of Health. Retrieved February 25, 2025, fromhttps://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/
12. Sharma, S., Sheehy, T., & Kolonel, L. N. (2013). Ethnic differences in grain consumption and their contribution to intake of B-vitamins: Results of the Multiethnic Cohort Study. Nutrition Journal, 12, 65.
13. Smithline, H. A., Donnino, M., & Greenblatt, D. J. (2012). Pharmacokinetics of high-dose oral thiamine hydrochloride in healthy subjects. BMC Clinical Pharmacology, 12, 4. https://doi.org/10.1186/1472-6904-12-4
14. Thomson, A. D. (2000). Mechanisms of vitamin deficiency in chronic alcohol misusers and the development of the Wernicke-Korsakoff syndrome. Alcohol and Alcoholism, 35(Suppl 1), 2–7. https://doi.org/10.1093/alcalc/35.supplement_1.2
15. Thomson, A. D., & Leevy, C. M. (1972). Observations on the mechanism of thiamine hydrochloride absorption in man. Clinical Science, 43, 153–163. https://doi.org/10.1042/cs0430153
16. Young, R. C., & Blass, J. P. (1982). Iatrogenic nutritional deficiencies. Annual Review of Nutrition, 2, 201–227. https://doi.org/10.1146/annurev.nu.02.070182.001221
17. Tallaksen, C. M. E., Sande, A., Bøhmer, T., & others. (1993). Kinetics of thiamin and thiamin phosphate esters in human blood, plasma, and urine after 50 mg intravenously or orally. European Journal of Clinical Pharmacology, 44, 73–78. https://doi.org/10.1007/BF00315357
18. Food and Agriculture Organization & World Health Organization. (2005). Vitamin and mineral requirements in human nutrition (2nd ed.). World Health Organization.
19. Collie, J. T. B., Greaves, R. F., Jones, O. A. H., Lam, Q., & Bellomo, R. (2017). Vitamin B1 in critically ill patients: Needs and challenges. Clinical Chemistry and Laboratory Medicine, 55(11), 1652–1668. https://doi.org/10.1515/cclm-2017-0054
20. Hazell, A. S., Faim, S., Wertheimer, G., Silva, V. R., & Marques, C. S. (2013). The impact of oxidative stress in thiamine deficiency: A multifactorial targeting issue. Neurochemistry International, 62(6), 796–802. https://doi.org/10.1016/j.neuint.2013.01.009
21. Mrowicka, M., Mrowicki, J., Dragan, G., & Majsterek, I. (2023). The importance of thiamine (vitamin B1) in humans. Bioscience Reports, 43(10), BSR20230374. https://doi.org/10.1042/BSR20230374