# meaning of "nutritional tangents"

I'm reading The Fermented Man by Derek Dillinger. The author has this one-year plan of eating only fermented food, such as yogurt and bread. As a result, his options become extremely limited. Then he says:

...this year, this diet, was not easy. I definitely hadn’t started it to prove any scientifically valid points about nutrition or health, and yet the deeper into the year I got, the more tangential health issues it raised. I fell down rabbit holes I could have never seen coming. I got stuck, often, on nutritional tangents. I hoped the way I was eating wouldn’t kill me, as this particular project would be a pretty stupid way to do myself in.

I'm confused about his use of "tangential" and "tangent" here. The dictionary says "tangent" is "a straight line or plane that touches a curve or curved surface at a point, but if extended does not cross it at that point". And "tangential" means "of or along a tangent".

The definitions just confuse me more. In this case, what is a nutritional tangent? Does "tangential" simply mean that the issues he's faced with are related to health? When he says he "got stuck on nutritional tangents", does this mean he doesn't have enough nutritions? Or that he worries about his nutritions? Those are just my wild guess. Can anybody explain what he means for me?

• I’m upvoting this as a model “What does X mean?” question. You’ve included your research and pinpointed your source of confusion. Nice work.
– J.R.
Commented Aug 10, 2017 at 10:20

"Tangential" is being used in a figurative sense here to mean "essentially on a divergent topic."

The analogy is to the tangent to a curve in mathematics. The tangent to a curve touches the curve at only one point (I am oversimplifying the mathematics here). It may diverge greatly from the curve at points distant from the point of tangency.

So the meaning here is that the topics that are tangential have their source in some perhaps minor aspect of the main topic being considered but then become completely independent.

If you look it up in the dictionary, one of the meanings of tangential is:

3. divergent or digressive, as from a subject under consideration: tangential remarks.

In my opinion, this is opposed to what is often called a balanced/healthy diet.

The tangential curve has the tendency to both rapidly increase and decrease. When you compare this to a person's diet, you can imagine it as being volatile and therefore unhealthy.