All herbs are not the same.
1. Food Grade herbs are herbs you can eat every day and they will provide ongoing nourishment and balance.
2. Medicinal Grade herbs to be used as sparingly as possible for short periods of time.

How to Understand the Differences:

Medicinal herbs are much like western medicine in that their effects. Most medicines have an effect on the body by SUBSTITUTING or BLOCKING certain chemistry in the body.

An example of a substitute is insulin. Insulin is a hormone produced in the pancreas. If the pancreas is damaged or the insulin cannot gets to the cells, we can make insulin in a lab and inject it directly into our bloodstream.
This saves our life in many cases, but does not solved the problem of why there was insufficient insulin getting to the cells. There are always side effects to these kinds of medicines because the body becomes lazy in the sense that it stops producing its own medicine.

n fact this is what happens even with insulin. If a healthy person starting injecting large amounts insulin every day, they would become temporaitly diabetic in the sense that if you stopped injecting insulin there would be period of adjustment.

Food Grade Herbs Only Feed the Body.

Food grade herbs do NOT substitute or block chemistry in the body. They only provide the nutrition or building blocks for the body so that it can make its own medicines. This means you can eat food grade herbs every day with no side effects or later withdrawal.

Medicinal Herbs ARE Different From Drugs in Certain Ways

Medicinal herbs are different from synthetic drugs in the sense that they came from whole foods so they still have a whole food structure. Besides just the active ingredient, there are many other phyto chemicals which have slight enhancing or moderating effects on the ‘active ingredient’.
For this reason medicinal herbs are often easier and less powerful than drugs and many people feel they are more ‘natural’ and helpful. The usefulness of the herbs may then depend upon the skill the herbalist using the herb since it is a complicated science.

Foods and Food Herbs Are Different From Isolated Vitamins and Minerals.

In the same way that a drug is an isolated form of a whole food herb, an vitamin or mineral supplement is an isolated form of an ingredient from a whole food or whole food herb.
Using a whole food or a whole food herb is usually a more safe and holistic way to nourish the body. Once you start looking at isolated nutrients its gets very complicated very quickly. When you conider that a a typical diet provides more than 25,000 bioactive food constituents, that all interact with each other, you can see the problem in trying to figure it out in your head.
It is often easier to use what nature has provided with thousands or millions of years of evolution and what older cultures have food to be helpful over hundreds and thousands of years.