In propionic acidemia , a rare inherited genetic disorder, propionate acts as a metabolic toxin in liver cells by accumulating in mitochondria as propionyl-CoA and its derivative, methylcitrate, two tricarboxylic acid cycle inhibitors. Propanoate is metabolized oxidatively by glia , which suggests astrocytic vulnerability in propionic acidemia when intramitochondrial propionyl-CoA may accumulate. Propionic acidemia may alter both neuronal and glial gene expression by affecting histone acetylation.   When propionic acid is infused directly into rodents' brains, it produces reversible behavior (., hyperactivity , dystonia , social impairment, perseveration ) and brain changes (., innate neuroinflammation, glutathione depletion) that may be used as a means to model autism in rats. 
The above labelling rules do not apply to foods (including drinks) where caffeine is added for flavour rather than for a physiological purpose. These types of foods and drinks must comply with EU flavouring legislation (Regulation (EC) No 1334/2008). This limits the use of caffeine for flavouring purposes and sets maximum levels depending on the particular food or drink it is used in. For regular soft drinks like cola, the maximum amount of added caffeine permitted is 150 mg/l. The EU labelling legislation (Regulation (EC) No 1169/2011) requires that where caffeine is used as a flavouring, the term ‘caffeine’ must appear after the word ‘flavouring(s)’ in the list of ingredients.
A. Adding nutrients to a cereal can cause taste and color changes in the product. This is especially true with added minerals. Since no one wants cereal that tastes like a vitamin supplement, a variety of techniques are employed in the fortification process. In general, those nutrients that are heat stable (such as vitamins A and E and various minerals) are incorporated into the cereal itself (they're baked right in). Nutrients that are not stable to heat (such as B-vitamins) are applied directly to the cereal after all heating steps are completed. Each cereal is unique -- some can handle more nutrients than others can. This is one reason why fortification levels are different across all cereals.