Aspartame is a sugar substitute and is available under the brand name of Nutrasweet and Equal. It is 200 times sweeter than sugar.It has been approved by FDA in 1993 for inclusion in all foodstuffs such as fast food items with no restrictions and as an ingredient in sugar-free sodas. This chemical changes to formaldehyde, phenylalanine and methanol in the human body, or when a product containing it is heated to more than 30 degrees C. Formaldehyde is typically used to preserve dead bodies, and methanol is a deadly neurotoxin, commonly known as wood alcohol. Over 92 known side-effects are caused by ingestion of Aspartame (known to the Food and Drug Administration), including vomiting, anxiety attacks and tinnitus (ringing in the ears). Ingestion of Aspartame-containing foods has resulted in several deaths. It's even a component in most chewing gums. Symptoms may be delayed or immediate. Like MSG, its effects are both immediate (in particularly sensitive people) and delayed. However, there is no supportive research to prove the harmful after effects of Aspartame but the sensitivity may differ with the individual.

Cyclamate is the sodium or calcium salt of cyclamic acid (cyclohexanesulfamic acid). It is 30 times as sweet as sugar It is used in food,soft drinks,canned fruits, candy, salad dressings.
In the United States, the FDA banned the sale of cyclamate in 1970 after lab tests indicated that large amounts of cyclamates caused bladder cancer in rats. However, there are other views on this subject. Cyclamates are still used as sweeteners in many parts of the world. They are used with official approval in over 55 countries.

The Flavoring agents are used because some flavor loss occurs either totally or partially during the processing of food such as heating, concentration or drying. Flavoring agents is the largest group of food additive with 1200 varieties, comprising of both natural and synthetic flavors.

Besides, there is an other group known as 'Flavor Enhancers' which by themselves do not have flavors but enhance the flavor when added to food without imparting a distinct flavour of their own.One such product is Mono Sodium Glutamate or better known as 'Ajinomoto' used, largely in Chinese cooking.

Monosodium Glutamate (M.S.G) – It is used in processed foods, fast-foods and Chinese food as a flavor enhancer. It is found in most commercial soups, and soya sauce. It is found naturally in human bodies and in protein-containing foods, such as mushrooms, seaweed, tomatoes, fermented soy products, yeast extracts, nuts, legumes, meats and most dairy products.

There are some controversies regarding their effects on humans.It is claimed that headache and flushing of the skin, are relatively mild side effects whereas there are sustained physical problems such as asthma, acute headaches, and life-threatening heart irregularities.

MSG is not an allergen, according to the American College of Allergy, Asthma and Immunology. The U.S. Food and Drug Administration has found no evidence to suggest any long-term, serious health consequences from consuming MSG. It is possible that some people might be sensitive to MSG, just as to many other foods and food ingredients and therefore under current FDA regulations, when MSG is added to a food, it must be identified as "monosodium glutamate" in the label's ingredient list. Each ingredient used to make a food must be declared by its name in this list.

It is therefore advisable to keep a check as the side effects depend on the sensitivity of the person towards MSG

For Further reading Ref: Food Constituents : Problem Additives - http://interactive.usask.ca/ski/agriculture/food/foodnut/constit/constit_add4.html