Blog Post

Ashwagandha for Health and Performance

ashwagandha supplement

Ashwagandha (also known as Withania somnifera) is a herb that is common in Ayurveda, which is a type of alternative medicine that originated in India more than 3000 years ago. 

This herb falls into the category of an “adaptogen” which is defined as substances that are used in herbal medicine to help your body to respond to stress, anxiety, and fatigue, or to improve overall wellbeing.

A Quick Preface

Although it seems out of place for an evidence-based dietitian to be talking about a herb used in alternative medicine, it makes a bit more sense when we look at it from another perspective. 

Alternative medicine is defined as “any practice that aims to achieve the healing effects of medicine, but which lacks biological plausibility and is untested, untestable or proven ineffective.”

If that is the definition of alternative medicine, what happens if something that is utilised in alternative medicine does get tested thoroughly and becomes proven to be effective? 

Theoretically, it would no longer meet the criteria for being classified as alternative medicine. 

I am certainly not suggesting that Ashwagandha stands up to that level of scrutiny. 

Instead, I just want us to look at this topic from that perspective. Theoretically, if a lot of evidence existed supporting the use of ashwagandha for a variety of situations, it would transition from being an “alternative” to being a part of evidence-based practice.   

In this article, we are going to be exploring the evidence on the topic and making some interpretations for how and if it should be utilised in practice. 

Stress and Anxiety

The most consistent benefit of ashwagandha appears to be the ability it has to help reduce feelings of stress.

A great example of this was a study involving 64 participants with a history of chronic stress, where the intervention group was instructed to consume 600mg of ashwagandha per day. 

In this study, self-reported stress decreased significantly more in the ashwagandha group than in the placebo group. 

This is quite promising.

Self-reported stress of people taking ashwagandha

Some Weird Aspects of the Research

One thing about that previously mentioned study that stands out a lot to me is that it highlights a common issue amongst ashwagandha research. A lot of the research has some suspect aspects. 

The study was titled: “A Prospective, Randomized Double-Blind, Placebo-Controlled Study of Safety and Efficacy of a High-Concentration Full-Spectrum Extract of Ashwagandha Root in Reducing Stress and Anxiety in Adults.” 

Weirdly enough, participants were not allowed to be included in the study if they had anxiety. 

I have seen a lot of people reference this study for the reported benefits of improving anxiety, due to the title. It just seems kind of weird to include that in the title since it is not something that was actually involved in the study.

Another weird aspect of the study was that they mentioned that symptoms of depression were reduced by 77% in the ashwagandha group, but only 5% in the placebo group. 

Once again that seems promising until you factor in that nobody in the study had depression at the baseline since if they did, they would have been excluded from the study.  

Other Research on Stress/Anxiety

Another study involving a lower dosage (240mg) also showed improvements in stress levels in those who were stressed at the baseline.

It seems like a common theme that ashwagandha reduces perceived levels of stress.

Anxiety is often paired with stress when people are talking about ashwagandha, but there is not actually much research on the topic.

systematic review covering all the research on ashwagandha and anxiety highlighted that all the research so far has been promising, but due to the number of flaws in the research, it should be interpreted very cautiously.

Stressed Male


There also is not a lot of research on ashwagandha and depression, unfortunately. 

In addition to findings like the ones previously mentioned, which really are not overly relevant, there is only a small amount of specific research on ashwagandha and depression. 

The most relevant study I am aware of involved patients with schizophrenia taking 1000mg of ashwagandha per day. The outcome was a significant improvement in depression scores.

Once again, this is promising but is more of a topic that is worth further research. I wouldn’t be making strong conclusions in this area yet.


In the study mentioned earlier where 240mg of ashwagandha per day was consumed, testosterone levels increased a bit in men, but not in women.

Another group of men taking Ashwagandha for 8 weeks had their testosterone increase by 14.3% more than the placebo group.

A systematic review of all the research on the topic found 5 relevant studies (1 observational and 4 RCTs). The authors identified an average increase in testosterone of ~17%, although they cautioned that there is still only a small amount of research. 

Personally, while I find this interesting, it is also not at a stage where I am recommending it specifically for those purposes. 

Another aspect I wonder about is whether this change in testosterone is due to being less stressed. If somebody did not feel stressed in the first place, would they get these benefits? 

Strength and Muscle Growth

There is an 8-week study involving 600mg of ashwagandha per day in untrained lifters performing a resistance training protocol.

When you hear the results, you should instantly be a little bit skeptical.

Over the 8 weeks, the placebo group increased their bench press by 26.4kg on average. That’s a great progress for 8 weeks. But it’s also not unheard of for untrained lifters to make great gains like that.

The ashwagandha group though? They gained 46kg on their bench press during those 8 weeks. That is insane. 

They also had less muscle soreness/damage, more muscle gain, increased testosterone, and reduced body fat in comparison to the placebo.

See the image below for a summary of the results.

Ashwgandha and strength

This is another area that looks promising based on an individual study. It leads to an important question – if it works this well, shouldn’t everybody be taking it?

Another study was performed on recreationally active men and showed improvements as well, albeit on a less impressive scale.

In this study, squat increased by an average of 19.1kg in the ashwagandha group and 10kg in the placebo group. Bench press increased by 12kg and 8kg respectively.

It is not uncommon for studies on untrained participants to show large improvements quickly that can overrepresent how effective a supplement is.

A systematic review on the topic highlighted that the evidence is consistent enough that it is likely that ashwagandha helps strength and muscle growth, although it is worth being cautious since the effect size likely is smaller than some studies make it look.

As an additional thought, potentially this could also be related to improvements in stress levels or improved sleep as well. The benefits might be indirect, rather than direct. It is hard to tell though. 


Ashwagandha has been consistently shown to improve Vo2 max, although, like other areas, research is limited.

There is also research showing that elite cyclists improved their endurance performance while taking ashwagandha, in comparison to placebo.

This is another area where the results seem promising, but it is too early to make strong recommendations.

Blood Glucose Levels

There is promising research that ashwagandha can help manage blood glucose levels.

systematic review found that there were just over 20 relevant studies on the topic, of which 5 were clinical trials.

The outcomes found that blood glucose levels were significantly reduced with ashwagandha.

Unfortunately, there is no long-term data on the topic. Ideally, we would also have research on HbA1C levels to see if it helps over a longer timeframe.

Once again, it is another area that is promising, but it is also not at the stage where I am going out of my way to recommend it to clients with diabetes yet.

It also happens to be another area where stress can play a role. High stress often increases blood glucose levels

Ashwagandha and blood glucose levels

Sleep Quality/Quantity

The Latin name for Ashwagandha is “Withania somnifera” which translates to “sleep-inducing.”

Ashwagandha has research supporting the possibility that it can help improve sleep quality and quantity.

This benefit appears to be relatively consistent, although it is often not a large benefit.

The benefits also appear to be larger in those with insomnia, although that is not unexpected either.

As with other areas that ashwagandha helps, the outcomes here could be related to reductions in stress, which indirectly help improve sleep.

Dosage and How to Take?

Dosages anywhere between 200mg and 1000mg per day seem relatively common. Sometimes it is taken all at once, other times it is split up.

The most common effective dosage in research seems to be 600mg per day split over two dosages (morning and night).

Specifically choosing an ashwagandha product that is sourced exclusively from the root, instead of the leaves, seems to be the most common way to use it as well. KSM-66 is a great example of that.

That does not mean that this is the only way to take ashwagandha, but based on what I have seen, it is the most common way. And since there are so many gaps in the research, to me it makes sense to have the type that has been studied the most thoroughly.

How to Take Ashwagandha

Side Effects

Side effects from normal dosages of ashwagandha seem rare.

In high dosages, it might cause symptoms such as stomach upset, diarrhea and vomiting.

For autoimmune conditions, it has been proposed that caution should be warranted. This is based on the thought process that ashwagandha could improve immune function, which could be detrimental in these cases. There is no evidence of any issues, so at this stage, it is just theoretical. 

There is also research that has linked ashwagandha with an increase in thyroxine levels. It is not necessarily a strong link, but if thyroid issues are relevant, it could be worth being cautious. 

Practical Summary

Whether or not ashwagandha is worth taking really comes down to how okay you are with taking something on the possibility of it working well, or not at all.

The majority of research involving ashwagandha is positive. Sometimes it looks too good to be true as well. 

There are clear gaps in the research though. And a lack of quality research overall.

For stressed individuals, I think the research is consistent enough that it is worth considering taking. For most of the other benefits, I am pretty comfortable waiting a bit longer for more research before coming to strong conclusions. 

Since there appears to be a minimal downside to ashwagandha though, if it is something you are interested in, it could be worth considering. 

By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been interested in all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.