The decline of eyesight as we age is considered normal. The need for glasses to read is a hallmark of aging — print seems to get smaller and smaller as we age.

But what if this change were not inevitable? What if there were cultures where aging did not include a reduction in vision?

It turns out there is some evidence that, while visual decline is very common, it may not be universal or inevitable. A new study of an Amazonian tribe that still lives a “hunter-gatherer” lifestyle showed their eyesight does not decline with age. What made this study even more interesting is that researchers tested the vision of a nearby tribe that farmed their food, whose lifestyles otherwise were very similar to the first tribe. The members of the second tribe started out with good vision when younger, much better than in our culture, but there was a noticeable decline as they aged.

The researchers also studied the diets of the two tribes. The biggest variation was in the number of different food sources for the hunter-gatherer tribe, which ate 130 different food species, 80 of which were wild plants. By contrast, the farmers ate 63 species and only four wild plants. The researchers theorized the wide variety in the diet of the first tribe protected them against visual decline as they aged, and the organic, natural diet of the farming tribe allowed them to start life with excellent vision. However, the comparative lack of diversity did not protect their eyesight as they aged.

These findings are similar to previous studies that found blood pressure does not increase with age in hunter-gatherer tribal humans. Another Amazonian tribe was studied, and researchers found only 3 percent of adults had signs of high blood pressure. In America, 60 percent of adults have pre-hypertension or high blood pressure.

In our culture, we have access to some different foods, but I doubt any of us eats 130 different species or anywhere near 80 species of plants. The foods we eat tend to be mass-produced, which gives a much greater quantity of food at a very low price. The downside of our system is that it also tends to rely on very few species — especially corn, wheat, beef and rice — and heavily on chemicals and drugs to produce them. This leads to foods that are of lower nutrient quality.

The great nutritional pioneer Dr. Weston Price made similar observations in the 1930s, when he traveled the world looking at native human diets and health. Being a dentist, he primarily looked at oral health, which he found to be consistently better among the natives than the Europeans. When the natives began trading with the Europeans for white flour, sugar and canned foods, their health began to decline as well.

Until our food system changes, it is up to us to improve our diets and thereby our health, including our vision. My standard advice is to shop at the farmers market. Not only will you find organic, healthier foods, but you also tend to find foods you never even knew existed, such as purple cabbage, strange-shaped lettuce and red carrots. This new study suggests that eating a wider variety of these veggies is helpful.

For those of us who are new to eating organic, perhaps the farmers could put out large-print signs that are easy for us to read.

Dr. Michael Noonan practices chiropractic, chiropractic acupuncture and other wellness therapies in Old Town. He can be reached at noonanchiropractic@gmail.com.