When you think of ways to improve the health of your heart, eating a well-balanced diet and exercising probably comes to mind (though you may not do them!). Those things are definitely important – by far most important, in fact – but there are other heart-healthy things you can do, too. It may be time to start taking some relaxing, hot baths, as one study found that taking 5 hot baths a week was associated with a lower risk of heart disease.
Researchers from Ehime University in Japan wrote in the journal Nature that taking at least 5 hot baths a week can lower a person’s blood pressure as well as their risk of heart attack and stroke. That’s a lot of relaxation!
In the study, Prof. Katsuhiko Kohara and a team of colleagues asked 873 study participants aged 60 to 76 years old to complete a questionnaire regarding their hot water bathing practices. 
“Hot” water was defined as water having a temperature of over 41°C (105.8°F) for an average of 12.4 minutes at a time.
Researchers determined cardiac health by measuring brachial-ankle pulse wave velocity, which is a measure of atherosclerosis, and plasma levels of B-type natriuretic peptide, which is a standard measure of cardiac loading.
The team was able to include in the study longitudinal data they had on 164 of the participants, all of whom had undergone a minimal of 2 medical examinations, averaging a follow-up period of almost 5 years.
Participants who said they took at least 5 hot baths a week every week showed significantly lower markers of atherosclerosis and cardiac loading, the study found.
The authors said in the report:
“Water immersion is associated with increased volume of strokes, reduction of heart rate, an increase in cardiac output, and reduction of total peripheral vascular resistance. [However,] it has also repeatedly demonstrated that hot water immersion has favorable effects on cardiovascular function in patients with heart failure. 
Heat exposure shares the mechanism observed in sauna bathing, increasing core temperature, heart rate and contractility, redistribution of blood flow, and changes in conduit vessel endothelial shear stress. Elevation of core body temperature and increase in blood flow show similar physiological effects to those seen in exercise, which may account for the positive vascular effects associated with hot water immersion.”
Taking a hot bath for cardio-therapeutic reasons is known as “passive heating.” According to WebMD, passive heating could help lower blood sugar levels, decrease inflammation, lower blood pressure, and – as Ehime University scientists found – decrease the risk of heart attack and stroke. Though the research is only in its early stages.
That doesn’t mean that you should abandon a healthy diet and quit exercising to open up time for hot baths, though. Bathing in hot water 5 times a week should be viewed as another weapon in the arsenal against heart disease – something that should be included in an already-healthy lifestyle.
Baths Should be Part of an Otherwise Healthy Lifestyle
In the end, the individuals who benefitted from 5 hot baths a week may have benefitted from them so much because they already were leading a heart-healthy lifestyle. 
Prof. Jeremy Pearson — an associate medical director with the British Heart Foundation (BHF) in the United Kingdom (U.K.) who was not involved in the study – said:
“This study shows an association between having regular hot baths and some indicators of better heart and circulatory health.
However, this is just an observation and might be related to other lifestyle factors, such as people who have regular baths may also be more likely to live a low-stress lifestyle, or have a healthier diet.
Far more research is needed to understand the link before doctors start prescribing a hot bath to the elderly.”
Not for Everyone
Some people, such as those with multiple sclerosis (MS), migraine headaches, or auto-immune diseases, shouldn’t soak in a hot bath, as doing so can make symptoms worse. 
Though the study found that soaking in hot water is beneficial for those with heart disease, the Cleveland Clinic warns that people with existing heart conditions should avoid hot baths and hot tubs entirely.
Cardiologist Dr. Curtis Rimmerman explained on Cleveland Clinic’s website:
“A sudden rise in body temperature creates significant stress on the cardiovascular system, predominantly via a cascade of adjustments resulting in an elevated heart rate. The higher heart rate – especially in the presence of reduced heart function, heart arrhythmias, and coronary artery blockages – can precipitate a cardiac event such as blood flow problems and, in the worst case scenario, manifest as a heart attack.”
If you have a heart condition, talk to your doctor before immersing yourself in hot water. But if you’re healthy, enjoy to your heart’s content, and reap all of the physical and mental benefits that come with lounging in a tub.
Don’t have a bathtub? Try try a sauna instead!