When British colonial doctors traveled to the Colonies to care for the British settlers in distant lands, they were consistently amazed by the absence of chronic diseases in native populations. In fact, originally, heart disease, obesity, diabetes, and cancer were referred to as the 'Diseases of Civilization' rather than 'chronic diseases.' Why? Because 'uncivilized' natives did not have these diseases. But, as indigenous  populations began to consume more and more of the food imported for the settlers, the colonial doctors noticed that chronic disease began to afflict the natives. It often took decades, but as traditional food ways diminished and 'Western' diets were adopted by traditional societies, Western diseases arrived, too. So that begs the question, "What was on those boats?"  

On my arrival in Gabon, I was astonished to encounter no cases of cancer... I can not, of course, say positively that there was no cancer at all, but, like other frontier doctors, I can only say that if any cases existed they must have been quite rare.
— Dr. Albert Schweitzer (reflecting back to 1913)

Dr. Albert Schweitzer, a doctor who received the Nobel Peace Prize for his missionary work, spent over four decades in a missionary hospital in Gabon (that's Africa, folks), treating thousands of natives each year. And initially, he found almost no cases of chronic disease. The natives seemed somehow immune. Over time, chronic disease developed, according to Schweitzer,as "the natives were living more and more after the manner of the whites." 

As you might imagine, a long, unrefrigerated sea journey was not possible for many types of food. Were the Colonists importing butter, eggs, and meat? No way. The foods shipped to the Colonies had to be far less perishable. What was the cargo? It was largely white sugar, white flour, and white rice. Could these foods be the cause of 'Diseases of Civilization?'