Ashwagandha ( Withania somnifera) is a small evergreen shrub whose roots have been used for centuries in Ayurvedic medicine. It is classified as an adaptogen, helping the body manage and adapt to stress. Vasodilation is the physiological process of widening blood vessels, which increases blood flow and regulates blood pressure. The question of whether this traditional herb acts as a direct vasodilator is a matter of scientific investigation. This article explores the current evidence regarding Ashwagandha’s specific impact on blood vessel function and its broader effects on heart health.
Ashwagandha’s Relationship to Vasodilation
The direct action of Ashwagandha on blood vessels is linked to its effect on the endothelium, the thin layer of cells lining the vessels. Endothelial function measures vascular health and the ability to produce nitric oxide (NO), a gas molecule that signals smooth muscle to relax and widen the vessel. Studies show that extracts of Withania somnifera can improve markers of endothelial function, suggesting a positive influence on the vascular system.
The active compounds, particularly the steroidal lactones called withanolides, appear responsible for this activity. Research using isolated animal aortic rings indicates that Ashwagandha extracts and its component Withanolide A exert a moderate vasorelaxant effect by enhancing nitric oxide generation. This suggests the herb supports the body’s own mechanisms for promoting vessel widening rather than acting as a strong pharmacological vasodilator.
In human trials, supplementation has been shown to significantly increase nitric oxide levels in the bloodstream. One study found that taking 1,000 mg of Ashwagandha daily increased NO by over 33% compared to baseline. This increase in NO, coupled with a reduction in oxidative stress markers, suggests that the herb contributes to a healthier vascular environment. This mechanism enhances vascular tone, allowing blood vessels to function more efficiently.
Broader Effects on the Cardiovascular System
While its direct vasodilation effect is moderate, Ashwagandha’s role as an adaptogen offers substantial indirect benefits for the cardiovascular system. Chronic psychological stress elevates cortisol, which contributes to increased blood pressure and heart rate variability. Supplementation has been consistently shown to reduce morning cortisol levels in chronically stressed individuals, sometimes by as much as 20% to 30%.
This reduction in stress hormones is associated with measurable improvements in cardiovascular parameters. Studies report that Ashwagandha intake can lead to lower aortic pressure, reduced arterial stiffness, and decreased radial blood pressure in stressed subjects. By dampening the chronic stress response, the herb helps mitigate the negative impact of stress-induced hypertension on the circulatory system. This mechanism is distinct from direct vessel widening but results in better overall heart and vessel performance.
The herb also contributes to long-term vascular health by positively influencing lipid profiles. Supplementation has been observed to reduce levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides. Improving these markers is an important aspect of maintaining clear and healthy arteries, which prevents the hardening that can impede blood flow.
Practical Dosage and Safety Considerations
For individuals considering Ashwagandha, clinical studies generally point to an effective dosage range of 300 mg to 600 mg of a standardized root extract daily. Some research, particularly those examining cardiovascular markers, has successfully used doses up to 1,000 mg per day. The supplement is well-tolerated, but common side effects can include mild stomach upset, nausea, vomiting, or diarrhea, particularly at higher doses.
Potential interactions with prescribed medications must be considered due to the herb’s physiological effects. Because Ashwagandha can lower blood pressure, combining it with antihypertensive drugs may lead to hypotension. Similarly, its potential to lower blood sugar means caution is warranted alongside antidiabetic medications, as this can increase the risk of hypoglycemia.
The herb is known to increase immune system activity, which can interfere with immunosuppressant drugs. Its mild sedative properties suggest that taking it with central nervous system depressants, such as anxiety or sleep medications, may cause excessive drowsiness. Individuals taking thyroid hormone medication should also exercise caution, as Ashwagandha may increase thyroid hormone levels. Before beginning supplementation, a consultation with a healthcare provider is necessary to ensure safety.