I'd like to say more about confirmation bias. Google puts us in touch with millions of studies , done over many, many decades and, in some cases, even all the way back to a century ago, without requiring us to understand what those studies mean and why they haven't been repeated.
I'll demonstrate the results of confirmation bias, which is defined as
a type of selective thinking whereby one tends to notice and to look for what confirms one's beliefs, and to ignore, not look for, or undervalue the relevance of what contradicts one's beliefs.
.
Scientists approach research by trying to
disprove their hypothesis. This is, I suspect, to avoid confirmation bias, which everyone is prone to. While I was in the shower, I sucked something out of my thumb that I want to use to demonstrate it. I decided on 'chocolate causes cancer.' When I Google chocolate and cancer I get a string of results that tell me that chocolate
prevents cancer. I find legitimate studies that confirm this, but they don't serve my hypothesis.
To reach my goal of proving that chocolate causes cancer, I try Googling 'carcinogens in chocolate.' That should be precise enough to give me the evidence I need to support what I want to prove. Sure enough, I get information about the benzoarenes, acrylamide and PAH in chocolate--all of these are said to be carcinogens. However, the articles I find are not from reputable sources and they don't contain convincing studies. So I refine my search to one carcinogen: acrylamide. I find some very convincing sources. In fact, the FDA is there, as is Forbes. I need to really prove my point, so I search for 'acrylamide cancer studies.' I find NCLB studies and trials published on Cancer.org. The Cancer.org one here
http://www.cancer.org/cancer/cancercauses/othercarcinogens/athome/acrylamide
says that there are two studies proving that acrylamide indeed causes cancer. However, the NCLB study, consisting of 12 trialss, says that there is no convincing evidence that acrylamide causes cancer.
http://www.ncbi.nlm.nih.gov/pubmed/22495255
I'll stick to those two, although I could dig up more conflicting studies, as can you. If this was not an experiment, confirmation bias might have me ignoring the NCBI study and going on to search for further studies that say acrylamide does cause cancer. I would then move on to the other chemicals and do the same thing.
But I am sitting with two conflicting studies in my experiment, so how do I process it without confirmation bias? First and most obviously, I weigh up the scope of the studies. 12 trials vs 2 trials. It is definitely moving in favour of chocolate not causing cancer. But if I have confirmation bias, I will not have read the NCBI study telling me that 12 trials show that chocolate does not cause cancer, and I would thus not tell you about them.
Now I must look more deeply at my subject: chocolate. How much acrylamide is actually in chocolate and how many other foods contain acrylamide. Turns out that
all cooked foods and some refrigerated ones contain acrylamide, with potato chips containing the most and chocolate containing so little that it isn't mentioned on the lists.
Secondly, I need to look at how well those acrylamide studies have been designed. The studies that say acrylamide causes cancer were trials done on animals. The studies that say acrylamide does not cause cancer were done on people. That adds another point to the 'chocolate doesn't cause cancer' side, given that we don't share the same physiology with animals.
The next part is the most difficult. I can't really understand the topic of my research until I understand cancer and its etiology. Since I can't get a medical degree today, I will look at a little of what doctors have said about the differences between cancers and their responses to acrylamide: I find that those with endometrial, kidney, and ovarian cancer are the only subjects that show MIXED results from acrylamide intake. All other kinds of cancer seem not to respond to it as a carcinogen.
Next, I must understand the chemical nature of my subject: acrylamide. I find that it is generated through the application of heats of up to a specific temperature, and it also forms when potatoes are kept in the fridge. With confirmation bias, I would tell you that potato chips, toast, chocolate, coffee, bread, and meat all contain cancer-causing acrylamide. Without confirmation bias, I would tell you that only foods that are excessively browned, chilled, or heated to too high a temperature contain acrylamide, which hasn't been proven to cause cancer.
I can generate an enormous number of studies over time proving something that I wish to prove. I can also generate an enormous number of studies over time proving the opposite. Without a medical degree, all my Googling is dangerous. With confirmation bias, all my googling is useless.
I was writing regularly for a client who has trademarked a particular surgery. Recently, they asked me to leave out the subject of pregnancy from all of my work for them. I dropped them as a client as a result. It wasn't because their surgery caused fertility problems--it actually resulted in improved preservation of fertility against other surgical options. But without all of the facts, even the tiniest and the most seemingly inconsequential ones, patients are being manipulated.
Why do I take things like this so seriously?
Take the suggestion above (from a 1925 study) that a litre of L.acidophilus milk daily may reduce seizures.
In 1982, pediatricians at the University of California School of Medicine in Los Angeles reported a case of near-fatal overdose in a 3-week-old boy who had been given potassium for colic. In this case, the potassium was contained in a salt-substitute added to an acidophilus solution as recommended in another paragraph of the colic discussion. After four days, the infant became lethargic and irritable and had an episode of gagging after which he became limp and stopped breathing. The parents began mouth-to-mouth resuscitation and immediately took him to an emergency room, where he was able to breath spontaneously. His potassium levels were extremely high but responded promptly to treatment
(
http://pediatrics.aappublications.org/content/69/1/117.abstract)
These seemingly innocuous suggestions made by those who aren't medically trained and don't understand the effects and causes of something like hyperkalemia, which is easily fatal, can kill people who take them at face value.