Acetylcholine is a neurotransmitter that plays a crucial role in the central nervous system (CNS) and the peripheral nervous system (PNS). It transmits signals across synapses, particularly in neuromuscular junctions, facilitating muscle contractions. Additionally, acetylcholine is associated with cognitive functions such as memory and learning.

Acute inflammation is a rapid and short-term protective response triggered by the body in response to injury, infection, or tissue damage. It is characterized by symptoms such as redness, swelling, heat, and pain.

Acute stress is a short-term stress response triggered by an immediate threat or challenge. It is a natural and adaptive reaction that prepares the body for quick action in the face of danger.

A term used in research to denote “as much or as often as necessary or desired.” For example, in both animal and human experiments, when subjects are provided with “ad libitum,” they are given full access to consume as much as they want.

The adaptive immune system is a subdivision of the immune system developed after birth in response to exposure to different microbes or diseases. Unlike the innate immune system, it responds slowly but is highly specialized. It delivers a targeted response against invading foreign particles and comes to action when the innate immune system fails to control germs from spreading or causing disease. B and T lymphocytes are part of the body’s adaptive immune system.

The adaptive stress response is a physiological and psychological reaction to stress that benefits the individual’s well-being. It helps the person cope effectively with challenges, promoting resilience and recovery.

Adaptogens are natural substances, often herbs, that help the body adapt to stress and maintain balance. They regulate stress response systems, protecting against chronic stress’s negative effects. Examples include Rhodiola Rosea, Ashwagandha, and Ginseng, which are traditionally used for stress reduction and resilience.

The definition of addiction is ambiguous, but it simply refers to a state in which an individual exhibits compulsive, out-of-control behavior and an inability to self-control (Philibin & Crabbe, 2015). In addiction, the out-of-control behavior is related to the substance’s use despite the negative consequences (Philibin & Crabbe, 2015).

Adrenaline, also known as epinephrine, is a hormone and neurotransmitter the adrenal glands produce in response to stress or excitement. It plays a key role in the “fight or flight” response, increasing heart rate, dilating airways, and redirecting blood flow to support the body’s immediate reaction to a stressful situation.

Advanced glycation end-products (AGEs) are harmful compounds formed when proteins or fats react with sugars in the bloodstream through a process called glycation. This process is accelerated by high-temperature cooking methods such as grilling, frying, and roasting. AGEs contribute to chronic inflammation and are linked to various health issues, including neurodegenerative disorders.