There could be. For example:
- If you decide to try fasting or caloric restriction, and overdo them or plan your calorie-restricted diet poorly, you could end up with nutrient deficiencies.
- If you get wacky about it and stop eating altogether, you’ll starve to death and die.
- If you take more than a micro-dose of lithium, you may feel kinda zoned out. The amount some take hoping to prevent dementia is the amount naturally found in well water, but missing in some water supplies, not the amount given to psychiatric patients.
- If you’re allergic to astragalus, you may have an unpleasant reaction.
- If you take antioxidants at the wrong time, you could end up negating the benefits of exercise.
- Some cancer researchers have suggested that increasing the levels of NAD in the body might (possibly) fuel the growth of cancer, if it already exists in the body (brain cancer and colon cancer being two examples).
In sum, all things in life have risks. You could choke to death trying to swallow a vitamin pill, or trip over your own shoelaces on the way out to the refrigerator, take a drive to the store and crash into a passing car, or make the news for having found a new and silly way to die.
But the risks of trying, in my opinion, need to be weighed against the risks of not trying. If we do nothing, we’re guaranteed to grow older and eventually die. From that POV, the risks seem reasonable to me. You’ll have to decide for yourself whether you feel the same way.