Herb extracts: how much is enough?

Maksim Khotimchenko

Nowadays, every person sometimes has to take medicines either because of sickness or because of the need to prevent illness and keep health. But how many pills are to be taken is always a very important question. Every drug label contains such information. Also, physicians have to make very precise prescriptions explaining patients how many, how often and when they have to take pills. This solves the problem because almost nobody is prone to break physician’s prescriptions. But in some cases it is not so easy.

Very often we do not get complete information about how to consume remedies for health. For example, when we take dietary supplements containing herb extracts. Herbs contain natural active compounds working the same way as officially approved drugs. But recommendations for their use is not so precise and may vary significantly in different brands. Then it is up to a person deciding how much of an herb extract he or she needs to take. This question is really tough.

The amount of active substance necessary for some effects in human is a very crucial part of pharmacology and a whole medicine. The quantity of active substance getting into a human body is termed “a dose”. There are several different types of doses being used in pharmacology. We can define effective, toxic and lethal doses depending on the consequences they lead to. We can calculate single and multiple (or course) doses. Very frequently we use such terms as lowest, average, and highest doses depending on how strong is the effect exerted by active compound.  And here is the tricky point leading to many mistakes.

In our lives we got used to a simple correlation: the more means the bigger, or larger, or stronger, etc. That is why many people think that the more amount of drug or herb extract we consume the stronger effects we get. But this is not so simple.

The very important part of the drugs’ mechanism of action is their influence on special targets located in organs and tissues in the body. They are named receptors. Drug active compound affects these structures and thus induces some alterations of functions regulated by these receptors. If we take very small amount of drug, it can affect only a few of receptors and its effect would be barely noticed. If we take higher dose of drug, the more receptors would be affected and involved in this process, and we can see the real effect. But there is no direct correlation between the number of receptors influenced by a drug and the effect we observe. Our body contains much more number of receptors that we need for body to function. They are named “spare receptors”. If drug or herb extract affect too many receptors the effect increases but slower than expected. If drug active substance affects all receptors of a certain type fitting this drug structure, the effect is not going to increase any more. In this case we can increase the dose but it would not result in increased effect. Generally, correlation between dose and effect looks like these curves below.

Dose effect correlation curve

Of course, not all drugs are so safe that we can consume them in amounts as much as we want with no bad consequences. Many drugs must be taken only with doctor prescription because they can induce toxic effects and even death if consumed in high doses. Even herb extracts may contain such very dangerous compounds. But marketing of these substances is strictly regulated by government and FDA and it is not possible to get it without special permission. So, if we you can buy a drug or an herb extract supplement in a nearby store or online shop, you can be sure that it is generally safe.

Nevertheless, recommendations for use of any drug or dietary supplement should be strictly followed. And this is very important for an herb extract consumption. And that is why. Herbs contain many different substances, and generally each of these substances affects several types of targets in the body. And thus, they induce many various effects, similar or opposite to each other, depending of the dose, health status, physiological peculiarities and many other factors. So, various doses of the herb extracts may exert different effects. Very well known drug aspirin is a very good example of such phenomenon. Doses of aspirin lower that 100 mg taken by an average adult man prevent platelet aggregation in blood. So, blood becomes more diluted and this is very helpful for the heart disease prevention. Doses of aspirin higher than100 mg activate platelet aggregation in blood via different mechanism, and this influence is opposite to the previous one. So, there is no effect at all. That is why aspirin is low doses is very much helpful for prevention of the heart disease, but its higher doses are absolutely useless from this point of view. Such phenomenon is termed “hormesis”.

Term “Hormesis” comes from Greek hórmēsis "rapid motion, eagerness". It refers some effects caused by only low doses of active compounds in humans or animals. The higher doses provoke no effect or even opposite effect. So called hormetic substances are very useful if taken in small amounts but they may be useless or sometimes dangerous if taken in higher doses. Generally, correlation between dose and effect they induce looks like this plot below.

Hormetic herb extracts

This correlation may vary, but there is always decrease of efficacy corresponding to the increase of a dose.

Mechanisms of hormesis phenomenon are not completely understood. They may be linked to

-          many substances in an herb extract exerting opposites effects in human;

-          multiple targets controlling opposite functions in the body;

-          different resistance of several similar but not the same types of receptors controlling the same functions;

-          different affinity of different types of receptors to an active compound;

-          other complicated intracellular mechanisms differently reacting to active molecules.

Hormesis is not so typical of officially approved drugs because of the strict regulations of the drug discovery and development procedures requiring full understanding of active molecule behavior in human body. Herbs and herb extracts very often cause hormesis phenomenon.

Active compounds contained by herbs are very complicated and affect multiple targets and pathways. One of the very interesting herbs with hormetic influence is Schisandra chinensis. This herb is very helpful for brain. It helps it to function better because of pronounced stimulating activity and protects it from some severe chronic diseases related to degeneration of neuronal network. Schisandra seeds contain a group of lignans termed schisandrins. The most active is Schisandrin B. This is a typical hormetic agent with predominating cytoprotective effects at low concentrations and cytotoxicity occurring at high concentrations. It was shown in research studies that 15 mg schisandrin B given to healthy male subjects is an effective dose. Higher doses do not induce brain protecting influence.

It should be noted that, nevertheless, Schisandra extract is pretty safe. A single oral dose 0.8 g/kg (i.e. about 50 g) or multiple doses (200 mg/kg × 30) do not cause any toxic signs in humans. But at the same time, they do not have health benefits for nervous system. To cause this effect it should be taken in very low doses.

Many people try to get this remedy and take it in high doses thinking it is healthier and here they make a crucial mistake. Only low doses are helpful and only low doses keep brain working perfectly for long years.

Of course, Schisandra is not the only herb with hormetic activity. Almost all adaptogen herbs function the same way. Therefore, recommendation for their use labeled on each bottle with adaptogens inside should be followed. Moreover, sometimes these recommendations have to be carefully analyzed. Only good thinking can help to keep our brain functioning better and longer.


Maksim Khotimchenko, Ph.D.

Vladivostok (Russia) – San Diego (USA)

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