 People with certain forms of early onset Parkinson's disease may benefit from boosting the amount of niacin in their diet. That's the upshot of a new study from the MRC toxicology unit at the University of Leicester, which studied fruit flies with a mutation that mimics the human disease. Niacin, or vitamin B3, is found in a variety of foods, including nuts and meat. The results reveal a mechanism for how this particular type of Parkinson's affects the brain and point to other drugs that may also help this subset of patients. Parkinson's disease occurs when dopaminergic neurons in a part of the brain called the substantia nigra are lost. This can happen for a variety of reasons, but in some hereditary cases the main problem is unhealthy mitochondria, the organelles that power the cell. Mutations in genes such as pink 1 prevent cells from clearing out defective powerhouses. When they accumulate, neurons can't get enough energy and die. The faulty mitochondria also release toxic molecules that damage their genes. Curiously enough, there's a compound in the body that's important for both energy generation and DNA repair. It's called NAD. With all the mitochondrial damage going on, perhaps in Parkinson's the molecule ends up in short supply. To find out, the team fed fruit flies with mutated pink 1 genes foods supplemented with niacin, which is made into NAD inside the body. With this extra source of NAD, the flies had far fewer defective mitochondria than their mutant peers on a regular diet. The vitamin also prevented the flies from losing neurons. The neuroscientists then asked whether stopping DNA repair from depleting NAD would protect the Parkinson's flies. The answer was yes. Genetically switching this function off kept mitochondria healthy and neurons alive, and it improved the fly's strength, mobility, and lifespan. The results suggest that in familial Parkinson's, available NAD is critical for keeping mitochondria in shape and the disease at bay. Drugs that block NAD consuming DNA repair already exist to treat cancer, loading up on niacin probably can't hurt either. While neither of these would be cures, they would expand treatment options for Parkinson's patients with faulty mitochondria.