(I'm very interested in the Quantified Self movement, which involves self-experimentation and self-tracking to gain self-knowledge. Seth Roberts, a professor of psychology at Tsinghua University in Beijing and emeritus professor of psychology at the University of California at Berkeley, is one of the pioneers of the modern Quantified Self movement. From time-to-time, he's going to contribute a "Make Yourself Healthy" essay for Boing Boing. — Mark)

Gail, who is now 70, grew up near Toronto. As early as she can remember, she had digestive problems — pain after meals and troublesome bowel movements (diarrhea and constipation). Her father, a doctor, sent her to specialists. They couldn't find anything wrong and implied it was all in her head. She had the impression her parents agreed. (Her mother had headaches for years. Her husband — Gail's father, the doctor — said it was all in her head. It turned out her mother had a brain tumor.)

Gail's digestive trouble got worse in her teens. She remembers eating a hot dog on the beach and doubling over in pain. Since then she had at least some discomfort all the time.

When she was in her thirties, an annual checkup found a tiny amount of blood in her urine, a condition called microscopic hematuria. It had none of the well-known causes (e.g., tumor). Her doctors shrugged. That's interesting, they said. No one said she should be alarmed. "Microscopic hematuria is an incidental finding, and whether physicians should test for hematuria in asymptomatic patients remains at issue," said a 2001 policy statement from the American Urological Association. Sometimes it goes away. Gail's hematuria never went away. It was observed again and again in annual checkups.

In her forties, she had gallstones and had her gall bladder removed. Her doctors told her you don't need a gall bladder.

In her fifties, she was diagnosed with Hashimoto's thyroiditis, a disease in which the thyroid is attacked by the immune system. She also had a lump in her thyroid. She had most of her thyroid removed and has been taking thyroid medicine ever since.

Because of her hematuria, she had her kidney function assessed every few years by a GFR (glomerular filtration rate) test, which measures how fast your kidneys filter blood. Lower rates indicate worse kidney function. Later she was tested yearly. She doesn't know why the testing was changed from every few years to yearly. For a long time her doctors didn't tell her the results of the test.

When she was 60, her doctor asked her to get a GFR test every six months. Apparently this was because her GFR was now below 90. Such declines are enormously scary because if they don't stop you lose kidney function and must get a kidney transplant or dialysis for the rest of your life. Over ten years, from when she was 60 to when she was 70, her GFR declined to 31.

In 2010, when Gale's GFR score reached 31, her doctor said your kidneys have really degraded. If they get worse — such as 15 or below — you may need dialysis. Dialysis would have meant a huge change in her life. She was very active. If she needed dialysis, she wouldn't be able to play tennis and badminton, garden, do yoga, and so on. Her doctor appeared to have no idea what was causing the degradation. He said her blood pressure was a little high and she should lose weight to lower it, although she was only slightly overweight.

This was the first time he had told her to do something to improve her kidney function. For the first time, she realized the danger she was in. She became quite upset. She phoned her daughter, Ginna. My doctor told me my kidneys are failing, she said. Ginna asked if there had been any warning. No, she said. Later Gail asked her doctor if she had IgA nephropathy — a question Ginna wanted her to ask — and her doctor said yes. IgA nephropathy is a condition in which IgA proteins (which circulate in the blood as part of the immune system) build up in the kidneys.

Ginna lives on Vancouver Island. She works in IT and teaches skiing. In 2010, her cat was diagnosed with cancer. Ginna took her to a naturopathic vet named Marlene Smith (now retired) at Tree of Life Veterinary Care, Courtenay, British Columbia, who told Ginna that cats evolved to eat only meat. All animals have an evolutionary niche and we should try to stay within it, said Smith. Ginna was impressed. She had been feeding her cat ordinary dry cat food. To make it dry a lot of carbohydrate had been added. An all-meat diet would contain no carbohydrate. Ginna put her cat on an all-meat diet. She improved a little. She lived nine months after the diagnosis of cancer, which was considered excellent.

Ginna began to read about paleo ideas — the evolutionary niche idea applied to humans. Websites such as Mark's Daily Apple. Books such as The Primal Blueprint and The Paleo Solution. She encountered many discussions of gluten intolerance, which was new to her. Gluten is a protein in wheat, barley and rye, which are recent additions to the human diet. From Kurt Harris, Ginna learned about the link between gluten intolerance and autoimmune disorders, such as Hashimoto's: "Nearly every common autoimmune disease is associated with at least an order of magnitude increased risk of celiac disease," wrote Harris. (Celiac disease is a severe form of gluten intolerance.) For example, a 2000 study found that celiac disease was about five times more common in patients with Hashimoto's than in patients with nondigestive problems and 13 times more common in Hashimoto's patients than in blood donors.

Why is gluten intolerance linked with many diseases, especially autoimmune diseases? The prevailing theory is that gluten causes inflammation in the intestines, making them more permeable, which allows gluten to leak into the blood. When gluten is in the blood, the immune system makes antibodies against it. Gluten resembles a protein in the body, so these antibodies start attacking proteins in the body.

One estimate is that 1% of the United States population has celiac disease. A third have a genetic variant that makes it more likely. Gail's endless abdominal pain was a good reason to think she might be gluten intolerant. Like most Americans, she ate gluten daily — toast in the morning, sandwiches, dinner rolls, pasta. Never had she not eaten it. Another reason to think she might be gluten intolerant was her Hashimoto's. A third was her gallstones, which Ginna had read are weakly linked to gluten intolerance. (Another reason, it turned out, was her IgA nephropathy. According to this article, "the renal disease most commonly associated with [celiac disease] is IgA nephropathy.")

In early 2011, Ginna told her mother to stop eating gluten (i.e., stop eating bread, pasta, and a few other things). Her mother didn't object. To Ginna's surprise, her mother did not find it difficult, maybe because it was so successful. Within a week, she felt much better. The abdominal pain/discomfort she'd had continuously since she was a teenager diminished considerably and she no longer had pain after meals. She was very excited about that. Within a few months, for the first time in thirty years, her waist became visible. She had been bloated for thirty years. "It was amazing to her," says Ginna. "To not be in pain all the time. She said I didn't realize how much pain I was in until I wasn't in pain anymore. She's become an anti-gluten evangelist."

It had taken ten years for Gail's GFR score to go from 90 to 31. A few months after she quit gluten she had another kidney test. Your score is slightly better, said her doctor. He implied that such a recovery wasn't unusual. Six months after that her score was 62 (Ginna made her ask for a number). That was a huge recovery, no longer close to needing dialysis. (The National Kidney Disease Education Program says a score above 60 is "in normal range.") Gail told her doctor she thought the improvement was because she'd given up gluten. "That's very trendy right now," said her doctor. They did not discuss it further.

Here is another case of kidney disease that got much better on gluten-free diet.

Plainly this shows the value of online health information — in this case, about gluten intolerance. Neither Ginna nor I knew it was correlated with autoimmune disease. This story also shows that valuable information may be hidden in your medical records. Long before Gail's GFK score reached 31, and her doctor said she might need dialysis, her GFK score had been getting worse. Google Docs and other tools make it easier to track such things than ever before.

You've heard knowledge = power countless times. This case is more complicated. Here, self-knowledge + scientific knowledge + trying new things = power. Does it make sense to ask your doctor pushy questions (such as what's my GFK score? — to Gail, that was pushy) and keep track? If you are unable to improve your score, maybe not. But, because of her daughter, Gail wasn't powerless. Ability to improve her health came from the combination of self-knowledge (GFK scores, Hashimoto's diagnosis), knowledge of the scientific literature (paleo, gluten intolerance), and a willingness to try new things (there was no guarantee that she was gluten intolerant).