Why are people getting healthier?

The New York Times runs an excellent article.  It is often forgotten how sick people used to be:

[Robert Fogel and colleagues] discovered that almost everyone of the Civil War generation was
plagued by life-sapping illnesses, suffering for decades. And these
were not some unusual subset of American men – 65 percent of the male
population ages 18 to 25 signed up to serve in the Union Army. “They
presumably thought they were fit enough to serve,” Dr. Fogel said.

Even
teenagers were ill. Eighty percent of the male population ages 16 to 19
tried to sign up for the Union Army in 1861, but one out of six was
rejected because he was deemed disabled.

Heart disease rates and even cancer rates (per age cohort, I believe) were higher in times past.

The big question, of course, is why people are so much healthier (or for that matter smarter, see the Flynn Effect).  It seems to be more than just better nutrition and sanitation.  Scientists are focusing on time in the womb plus the first two years of life.  Children born during the 1918 pandemic, for instance, fare much worse later in life in terms of health.  The hypothesis is that the poor health of their mothers programmed them for later troubles.

The Netherlands is a land of giants.  The people look quite healthy, despite high reported rates of disability.  Average height is 6’1" or 6’2".  And the Dutch are growing taller quickly.  Why?  Is it lots of Gouda cheese for Mommy?  The mayonnaise on the french fries?  Do small families play a role?  The Protestants of the northern Netherlands are taller than the Catholics of the south.  And if it is the cycling, are the teenagers in Davis, CA tall as well?