While gastric cancer is declining, it is still the most common cancer in Korea. Past studies have yielded conflicting results as to whether a salty diet causes gastric cancer, though most found an association between salt use and gastric cancer.
The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940.
That's a good point, but it's probably the organic acids rather than the salt (which the media report you've linked to blames). Bacteria which produce lactic acid are primarily used for traditional fermentation, I think, whereas distilled vinegar is made from ethanol by bacteria that produce acetic acid...
Hmm:
"Compared to acetic acid, [lactic acid's] pKa is 1 unit less, meaning lactic acid deprotonates ten times more easily than acetic acid does. This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group."
- https://en.wikipedia.org/wiki/Lactic_acid (emphasis added)
Not sure what the source is on that chart, but I'll assume it's credible. If that's the case, then despite what the article says, it's hard to believe that most of this decline is not accounted for by the decline in smoking. Surely the decline in smoking accounts for the vast majority of the lung cancer decline, and the peaks for colon and prostate cancer are very close to the same time.
Weird. Why would lung cancer go the opposite direction as smoking prevalence? I understand the dynamic of "cancer only kills people who outlive every other cause of death", but for the discorrelation to be that strong?
If I were to guess, the results lag behind the prevalence. It takes many years for someone to get cancer. If you were to push back the graph by 20 years it may correlate strongly.
Edit: Also, the U.S. banned asbestos in 1989. That's the turning point of the graph.
Wooow! That's lot of lung cancer deaths, counterintuitively coupled with air pollution elimination.
I wonder how this correlates not with tobacco smoking, but especially with smoking of factory-made cigarettes? Because as I understand those contain virtually no tobacco and you end up smoking garden fertilizer-soaked paper.
In the later 50's the FDA also put strict limits on the amount of sodium nitrite allowed in cured meats. And required the addition of ascorbic acid. The latter supposedly neutralizes the nitrite when the meat is heated/cooked.
The article suggests several possibilities, including increasing use of antibiotics, and less consumption of salted/cured meats, but the actual answer is unknown.
And actually that is the crux of the article: it's not that doctors aren't thinking of possibilities to explain the reduction in disease, they just don't know for sure which of the possibilities they are.
Basically, if we've thought of a possibility in the last 20 minutes since reading the article (or headline), a doctor has probably already thought of it, too.
I read an blog entry by a retired surgeon. He said when he started a lot of his bread and butter business was surgically fixing ulcers. Then came drugs to reduce stomach acid, followed by the discovery of Helicobacter pylori, and that business mostly went away.
Currently, South Korea and Japan have the highest incidences of stomach cancer. It's typically attributed to cured foods and processed meats. Prior to refrigeration, wide consumption of these foods were out of necessity.
