Beware MSG and aspartame. If you regularly experience severe headaches, dizziness, muscle aches and digestive discomfort, the cause may lie in your diet. Monosodium glutamate and aspartame are common food additives that are culprits in many common medical complaints. MSG contains glutamic acid, and aspartame contains aspartic acid. These substances, both of which are neuroexcitatory amino acids, have been associated with headache, nausea, impaired ability to concentrate, attention deficit disorder, dizziness, flushing, muscle aches, digestive complaints and more.