Complexes are vitamins that are actually themselves composed of different varieties, all needed to work in concert within the body. B-complex is composed of 8 B vitamins, with Vitamin B1 topping the list.
Typically, complex vitamins will all share part of a single purpose, and also have unique effects. For anyone who takes a special interest in supplementation, it can be useful to learn what each part of a vitamin complex does to help better choose which supplements may help them.
What Is It?
Vitamin B1 is so-named because it was the first vitamin of the B-Vitamin complex to be discovered and labeled. This is unique to Vitamin B1, as the numbers after the vitamin names are generally indicative of some part of the vitamin’s molecular structure.
Vitamin B1 is also called Thiamine or Thiamin. Thiamine is water-soluble, meaning that the body does not store any that is leftover after it uses what it needs.
What Is Its Biological Role?
All B-complex vitamins take a role in helping the body properly use carbohydrates. They accomplish this by aiding in carbohydrates’ transformation into glucose, a form of sugar that the body can easily adapt to various uses.
Thiamine specifically is needed by the body to make Adenosine Triphosphate, also called ATP. ATP is needed to help transfer energy between cells. If you think of all the cells in your body as having very tiny gaps between them, ATP is what your body uses to carry what it needs from one cell to another, bridging the gap.
How Does It Help Bodybuilders and People Who Work Out?
Some B-vitamins can help increase energy levels. This is why, if you read the labels of certain energy drink products, they will contain high levels of b-vitamins. Thiamine, therefore, can help fitness enthusiasts in two ways: helping you get the best of fatigue, and making the most of your lunch.
Some types of athletes will consume large amounts of carbohydrates before a long workout or competition in their sport. Without Thiamine, your body can have a hard time transforming those carbs into usable energy.
Also, because Thiamine gives you a boost of energy, it can help enhance your overall feeling of well-being while working out which can allow you to really push limits with your fitness regime. B-vitamins are water-soluble, and so you can “run-out” quite quickly when your body is under stress; supplementation may improve the quality of workouts.
What Foods Contain It?
Thiamine is prevalent in the organ meats of most animals, particularly the liver. It can also be found in most cuts of beef and pork, in eggs, seeds, and legumes. Certain foods such as breads and cereals are also commonly fortified with Thiamine to help consumers reach their RDA and avoid deficiency.
How Much Of It Do You Need?
Recommended daily allowance of Thiamine  varies slightly based on gender. Men are recommended 1.2mg per day, while women are recommended 1.1mg per day. A woman who is pregnant or breastfeeding is recommended a slightly higher dosage of 1.4mg per day.
Higher dosages are sometimes given therapeutically to combat illnesses including Alzheimer’s disease, coma, hypothermia, epilepsy, extreme menstrual cramps, and complications of alcoholism.
Are There Risks Associated With Consuming Too Much Of It?
Being that Thiamine is a water-soluble vitamin, it is extraordinarily rare to experience Thiamine toxicity. So rare, in fact, that is widely referred to as highly unlikely. That is because when you take high doses of water-soluble vitamins, any portion of the dosage that your body cannot immediately use gets flushed out of the body in urine.
Taking a very large dose at once for therapeutic reasons, however, may cause an upset stomach. For this reason larger doses are typically broken up and taken throughout the day so as not to upset the stomach.
Are There Risks Associated With Consuming Too Little Of It?
Thiamine deficiency is extremely rare in developed countries, as it is easy to get from diet between the foods it is naturally found in and the range of foods that have been fortified with Thiamine.
However, Thiamine deficiency causes a disease called Beriberi, which can affect multiple body systems. Symptoms include fatigue, nervousness, nerve damage, and mental health side effects ranging from depressed mood to psychosis. Thiamine deficiency caused by alcoholism is the most common cause of another Thiamine-related disease called Wernicke-Korsakoff syndrome.
Some groups, such as those with certain illnesses or who work out quite frequently may have elevated requirements for Thiamine and other vitamins. If this is the case they may benefit from the higher dosages of certain vitamins as available in supplements.
 University of Maryland Medical Center. Vitamin B1(Thiamine). University of Maryland Medical Center, 2015.
 Douglas, Ellen. What Happens When You Exercise With A Vitamin B Deficiency? . Livestrong.com, 2016.
 Mayo Clinic. Thiamine (Vitamin B1) Dosing Guidelines. The Mayo Clinic, 2013.