In the current section, the functions of nutrients such as polyunsaturated fatty acids (PUFAs), B group vitamins, calcium, zinc, iron, magnesium in the brain and the effect of diet on neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Amyotrophic Lateral Sclerosis and Multiple Sclerosis are discussed. PUFAs (Linoleic acid, α-Linoleic acid, eicosapentaenoic acid and docosahexaenoic acid), which maintain membrane fluidity necessary for synaptic vesicle fusion and neurotransmitter transmission within neural networks, are essential components of neuronal cell membranes. In older brains, there is a deficiency in PUFA levels in the cortex, hippocampus and cerebellum, which are associated with cognitive and motor functions. The brain has four times the amount of circulating methyltetrahydrofolate (folate) than plasma. The production of cholesterol, phospholipids, amino acids, fatty acids, steroid hormones and neurotransmitters is facilitated by pantothenic acid, which is a substrate for the synthesis of coenzyme A (CoA), which contributes to the structure and function of brain cells. Pyridoxine (vitamin B6) is a rate-limiting cofactor in the production of neurotransmitters such as dopamine, noradrenaline, serotonin, γ-aminobutyric acid (GABA) and melatonin hormone. Calcium is a very important factor in the normal functioning of neurons and the neuromuscular junction, as it transmits depolarizing impulses and contributes to synaptic activity. Since zinc is mostly stored in the hippocampus, amygdala, cortical regions and telencephalon, it has important effects on memory, cognition and emotional balance. Iron is essential due to its role in cellular metabolism, myelin production, and neurotransmitter synthesis. Magnesium is essential for controlling the activity of neurotransmitter receptors. It is known that there are significant amounts of microglial cells and activated pro-inflammatory cytokines in the postmortem brain tissue of Alzheimer’s patients, meaning that there is an important relationship between inflammation and the pathophysiology and cognitive failures of Alzheimer’s patients. Parkinson’s disease risk may be affected by dietary consumption of PUFAs and MUFAs (monounsaturated fatty acids). On the other hand, high consumption of PUFAs and vitamin E supplementation may protect against Amyotrophic Lateral Sclerosis (ALS). In Multiple Sclerosis (MS) patients with dysphagia, brain signaling defects affect respiratory muscle strength, making normal food intake difficult.