Thiamine, also known as Vitamin B1, is not an amino acid but a water-soluble vitamin. It plays a crucial role in energy metabolism by helping convert nutrients into energy, essential for nerve, muscle, and heart function. While amino acids are the building blocks of proteins, thiamine differs in structure and function. It is involved in several enzyme systems related to energy production and is critical for the synthesis of the neurotransmitter acetylcholine and for the metabolism of carbohydrates. Deficiency in thiamine can lead to beriberi, a disease affecting the cardiovascular and nervous systems, and Wernicke-Korsakoff syndrome, primarily seen in chronic alcoholism. Thiamine is found in foods like whole grains, meat, and fish, and it's often added to cereals and bread as a fortification.

Yes, fiber, particularly soluble fiber, can help reduce cholesterol levels in the blood. Soluble fiber binds with cholesterol particles in the digestive system, preventing them from being absorbed into the bloodstream. Instead, they are excreted from the body. Foods high in soluble fiber include oats, beans, lentils, apples, and citrus fruits. By incorporating these foods into your diet, you can potentially lower your LDL (low-density lipoprotein) or "bad" cholesterol levels. This reduction in LDL cholesterol can decrease the risk of heart disease. However, dietary changes alone may not be sufficient for everyone; lifestyle changes and medication might also be necessary depending on individual health conditions. Nonetheless, increasing soluble fiber intake is a beneficial and natural strategy to manage cholesterol levels.

Polyvinyl Chloride (PVC) is considered generally safe for use with rats, especially in the form of toys or housing components. It is a durable, easy-to-clean material that does not readily harbor bacteria or parasites, making it a suitable choice for pet environments. However, when choosing PVC items for rats, it is crucial to ensure they are free from phthalates, toxic chemicals used to make PVC more flexible, which can be harmful if ingested. Additionally, PVC should not be heated (including in direct sunlight) as it can release harmful compounds. In summary, while PVC can be part of a safe habitat for rats, it is important to select high-quality, phthalate-free products and use them in ways that avoid the release of harmful chemicals.