Final answer:
Trans fats have been banned from some restaurants because they increase the level of 'bad' LDL cholesterol, which can lead to heart disease. They are created through hydrogenation of vegetable oils and now food regulations require the trans fat content to be listed on labels.
Step-by-step explanation:
Trans fats have been banned from some restaurants due to their negative impact on health. They are created through hydrogenation, a process that converts liquid vegetable oils into solid fats by adding hydrogen. During hydrogenation, some of the natural cis double bonds in the fatty acid chains are converted to trans double bonds, which results in the formation of trans fats.
The chemical change of introducing trans double bonds affects the properties of the lipid, making it more saturated and stable. Unfortunately, this has been linked to numerous health issues. Trans fats increase levels of low-density lipoprotein (LDL) or 'bad' cholesterol, while simultaneously decreasing high-density lipoprotein (HDL) or 'good' cholesterol. This imbalance contributes to a higher risk of heart disease, as it can lead to plaque deposition within the arteries. Recognizing these health risks, many food providers have ceased using trans fats, and regulations require that trans fat content be listed on food labels to inform consumers.
Common sources of artificially hydrogenated trans fats include products like margarine, certain types of peanut butter, and shortening. The awareness of the dangers of trans fats, backed by scientific research, has led to industry and legislative changes aimed at reducing their presence in food and thereby improving public health.