My favorite n=1 experimenter, Seth Roberts, wrote about how someone managed to greatly reduce her migraines by avoiding certain household chemicals.
Sarah MacDonald (pseudonym) started getting migraine headaches the summer before she started college. During her first year of college, she was in a car accident and hit her head. Her migraines got much worse. More than once a week, she had to stay in bed all day, in darkness and silence, not eating anything. She tried pain killers. None worked. "They spread out the pain," she said. "They made me totally stupid." The only relief was sleep. The summer after her freshman year (2004), she stopped getting her period. In November, she saw a doctor near her university (Mount Allison, in New Brunswick). Blood tests showed that her prolactin was way off. The likely cause, said the doctors, was a tumor on the pituitary. But CAT scans and MRIs found nothing. The tumor must be small, her doctors said. It would grow and become visible. She waited for this to happen. Her doctors kept ordering new scans, looking for the tumor. Eventually she had two CAT scans and five MRIs. None found a tumor. During the year of waiting, she tried about fifty different drugs. None helped. I'm getting desperate, she told her doctors. "You need to give the medicine more time to work," they said. It was almost a requirement of treatment that she start taking birth control pills. Over the same year that she tried fifty drugs for her migraines, she tried thirteen different birth control pills, hoping to find one that was tolerable and made her migraines better. She never did. None of them made her migraines worse, but some caused nausea. In January 2006, unhappy with lack of progress, she stopped taking all medicines, including birth control pills. Her migraines didn't change. In April 2006, she moved to a new apartment. Because she didn't have a roommate, she had total control of her living space. She had been reading about environmental causes of migraines. She was especially impressed with Annie Bond's story. Bond lives in upstate New York. In the 1980s, after the restaurant where she worked had a gas leak and her apartment building was fumigated. Bond started having all sorts of health problems. They turned out to be due to chemicals in household products. Perhaps the conjunction of gas leak and fumigation made her hypersensitive. Bond's story, plus other stories Sarah found on the Internet, suggested that three sorts of chemicals were dangerous: 1. Sodium lauryl sulfate (a foaming agent). 2. Methyl and ethyl parraben (preservatives). 3. Artificial fragrances. Sarah purged her apartment of anything that contained them or similar chemicals: bodywash, makeup, shower cleaner, laundry detergent, all cleaning products, deodorant, anything that went on her body. She decided there were five household products she couldn't live without: moisturizer, deodorant, laundry detergent, dish soap, and toothpaste. She got new versions of them at a health food store. This helped a lot. "That summer  I missed only four days of work," she said. "It was miraculous and totally shocking." In the summer, she didn't have exams, which were stressful. Maybe the decrease in migraines had been due to less stress. When school resumed in the fall, however, her migraines continued to be relatively rare, about two per month. The elimination had really helped. During the 2006-7 school year, she had a roommate. They fought about cleaning. Her roommate liked the lemon scent of Mr. Clean. But something in Mr. Clean caused trouble. "If she cleaned the bathroom, I'd have a migraine the next day," said Sarah. Because the time between exposure and the resulting migraine was short, she was able to figure out which chemicals caused migraines. Over the school year, she introduced, one by one, dozens of cleaning products, usually ones her roommate wanted. She figured out that artificial fragrances were bad, as she had guessed, but that sodium lauryl sulfate and the parrabens were okay so long as she did not have direct contact with them. If her roommate used her own dish soap, laundry detergent, toothpaste, and body care products (shampoo, soap, moisturizer), Sarah was fine. After graduation, she moved to Kentville, Nova Scotia. She had to move her medical records, too, so she brought them to a general practitioner. He looked at them. "We'll need to have MRIs done," he said. I'm done with that, Sarah told him. It didn't go over well. Because of her GP's insistence -- she was still getting two migraines/month -- she saw another round of specialists: endocrinologist, gynecologist, ear nose and throat doctor, neurologist. The endocrinologist said, "There's a lot of scare stuff on the Internet. It's hard to pick out the good science. Most of it is placebo effect. You just think it works." He said this after Sarah had been immensely helped by "stuff on the Internet" and not helped by dozens of drugs. The (male) gynecologist insisted she take birth control pills. "You're being an idiot about this," he said. "You're 23 and you don't want to have kids." Sarah refused. The estrogen in birth control pills can make migraines worse, she said -- and she was seeing him because she had migraines. They argued so loudly the office manager could hear them. The gynecologist gave her a birth control prescription anyway, which she ignored. The neurologist did a 45-minute physical. When he was done, he said, "Yes, you've got migraines. Have a good life," and left the room. In 2008, her oldest brother, an acupuncturist, told her she should have a cleanse to get the toxins from the drugs out of her system. She decided to see a naturopathic doctor. (Naturopathic doctors are closer to conventional doctors than other naturopaths.) She saw Dr. Susan Ritcey, of Hawthorn Naturopathic Clinic, who specializes in migraines. Dr. Ritcey did something the conventional doctors had never done: study Sarah's tracking records. Sarah had recorded her periods, migraines, chemical exposures, and other things for several years. The doctor noticed there was a fixed period between the timing of Sarah's remaining migraines and the start of Sarah's periods, which she interpreted it to mean Sarah's progesterone levels were low. A saliva test confirmed this. (Conventional doctors, in Sarah's experience, never did saliva tests, although they were covered by her insurance. Researchers have used them to measure sex hormones, such as testosterone.) Dr. Ritcey prescribed a topical cream of wild yam to increase progesterone. Sarah applied it daily for three weeks before her period for three months. Her progesterone level became normal -- and her migraines less frequent. By now, they were almost gone -- less than one per month. She found that several triggers around the same time were required to produce one. Triggers included a drop in air pressure, exposure to cleaning chemicals (e.g., at school), and perhaps fluorescent lights. Everyone understands that conventional doctors can't always help. What's striking about Sarah's story is how easily she did better. Sarah's conventional doctors had gone to medical school, passed a licensing exam, trained as residents, and accumulated years of clinical experience. The research behind their recommendations cost billions of dollars (developing fifty useless drugs, for example). Sarah was an undergrad cognitive science major. Her research was free. Her conventional doctors would have discouraged her from seeing a naturopath. The American Cancer Society says that "available scientific evidence does not support claims that naturopathic medicine can cure cancer or any other disease." Yet her naturopathic doctor greatly helped her, while her conventional doctors arguably harmed her. The year she took their advice was a year she made no progress -- a year of excruciating and frequent migraines and fifty useless drugs.