Politics means the world of government in general:
The vice-president has a long career in politics.
I hate discussing politics with my family because it always turns into an argument.
Sometimes people talk about "office politics" outside the context of government -this means the connections and actions that people inside a company take in order to gain power, forming relationships and manipulating situations to their advantage.
A policy is like a rule. Countries have policies (foreign policy, immigration policy, gun control policy) but schools and companies do, too:
Our policy is that customers can return an item and get a refund within 30 days of their purchase.
My school had strict policies regarding lateness - if you were late more than five times, you got suspended.
Cysteine is an up and coming nutritional supplement. There is some evidence that cysteine (not to be confused with cystine) has certain therapeutic value as a nutritional supplement. Dr. H. Ghadimi, chairman of the nutrition committee at Nassau country, (New York) medical centre uses cysteine supplements to treat his patients suffering from obesity. He considers that there is link between obesity and over-production of insulin and that cysteine supplements taken along with vitamin C at the end of the meals somehow neutralises some of the excess insulin, which is responsible for fat production. He regards this amino acid as ' anti-cancer and anti-ageing' and claims that like vitamin C, cysteine protects the body from damage by oxidants.