Once more the usual health article caveat, that no medical or health advice is being offered, see a medical practitioner etc. etc. Now, to report some news, it has been claimed that blueberries are a delightful way of aiding in the problem of dealing with high blood pressure:
  https://life.spectator.co.uk/articles/eating-blueberries-can-help-lower-blood-pressure/

“Eating 200g of blueberries every day for a month can lead to an improvement in blood vessel function and a decrease in systolic blood pressure, according to a new study published in the Journal of Gerontology. Researchers from King’s College London studied 40 healthy volunteers for one month. They were randomly given either a drink containing 200g of blueberries, or a matched control drink daily. The team monitored chemicals in volunteers’ blood and urine as well as their blood pressure and flow-mediated dilation (FMD) of the brachial artery: a measure of how the artery widens when blood flow increases, which is considered a sensitive biomarker of cardiovascular disease risk. In a further study, researchers compared the effects of a blueberry drink with those of purified anthocyanins, a type of phytochemical responsible for the blue, red, pink and purple colour of some fruits and vegetables such as berries and red grapes. They also compared this with control drinks containing either similar levels of fibre, mineral or vitamins found in blueberries.

They found that:
•    Effects on blood vessel function were seen two hours after consumption of the blueberry drinks and were sustained for one month even after an overnight fast.
•    Over the course of the month, blood pressure was reduced by 5mmHg. This is similar to what is commonly seen in studies using blood pressure lowering medication.
•    The drinks containing purified anthocyanins led to improvements in endothelial function. Endothelial cells act as a barrier between the blood or lymph and the surrounding body tissue, as well as playing key roles in blood clotting and regulating blood pressure.
•    Neither the control drink, the control with fibre or the control with minerals and vitamins had a significant effect on FMD at two and six hours after consumption.

     The study’s lead researcher, Dr Ana Rodriguez-Mateos, said: ‘Although it is best to eat the whole blueberry to get the full benefit, our study finds that the majority of the effects can be explained by anthocyanins.’ ‘If the changes we saw in blood vessel function after eating blueberries every day could be sustained for a person’s whole life, it could reduce their risk of developing cardiovascular disease by up to 20 per cent.” That is about a bowl of blueberries a day, which could be further improved by adding turmeric, black pepper and maybe cinnamon to the bowl to add to the impact:
  https://www.ndtv.com/health/if-you-have-high-blood-pressure-you-must-have-cinnamon-spice-1898296
  https://www.livescience.com/41760-turmeric-supplement-facts.html

     Correct breathing has been shown to decrease blood pressure in essential hypertension: Hypertension. 2005 Oct;46(4):714-8. Epub 2005 Aug 29, “Slow breathing improves arterial baroreflex sensitivity and decreases blood pressure in essential hypertension.,” Joseph CN, Porta C, Casucci G, Casiraghi N, Maffeis M, Rossi M, Bernardi L.

     The technique appears to be to engage in slow breathing of 6 breaths per minute, thus breathing in, say, to a slow count of 8, holding for 7 or 8, then a slow relaxed exhale of about 8 as well. No shallow breathing of hyperventilation (fast breaths). This method, regularly practiced yield the following results detailed in the scientific abstract of the research paper:

“Sympathetic hyperactivity and parasympathetic withdrawal may cause and sustain hypertension. This autonomic imbalance is in turn related to a reduced or reset arterial baroreflex sensitivity and chemoreflex-induced hyperventilation. Slow breathing at 6 breaths/min increases baroreflex sensitivity and reduces sympathetic activity and chemoreflex activation, suggesting a potentially beneficial effect in hypertension. We tested whether slow breathing was capable of modifying blood pressure in hypertensive and control subjects and improving baroreflex sensitivity. Continuous noninvasive blood pressure, RR interval, respiration, and end-tidal CO2 (CO2-et) were monitored in 20 subjects with essential hypertension (56.4+/-1.9 years) and in 26 controls (52.3+/-1.4 years) in sitting position during spontaneous breathing and controlled breathing at slower (6/min) and faster (15/min) breathing rate. Baroreflex sensitivity was measured by autoregressive spectral analysis and "alpha angle" method. Slow breathing decreased systolic and diastolic pressures in hypertensive subjects (from 149.7+/-3.7 to 141.1+/-4 mm Hg, P<0.05; and from 82.7+/-3 to 77.8+/-3.7 mm Hg, P<0.01, respectively). Controlled breathing (15/min) decreased systolic (to 142.8+/-3.9 mm Hg; P<0.05) but not diastolic blood pressure and decreased RR interval (P<0.05) without altering the baroreflex. Similar findings were seen in controls for RR interval. Slow breathing increased baroreflex sensitivity in hypertensives (from 5.8+/-0.7 to 10.3+/-2.0 ms/mm Hg; P<0.01) and controls (from 10.9+/-1.0 to 16.0+/-1.5 ms/mm Hg; P<0.001) without inducing hyperventilation. During spontaneous breathing, hypertensive subjects showed lower CO2 and faster breathing rate, suggesting hyperventilation and reduced baroreflex sensitivity (P<0.001 versus controls). Slow breathing reduces blood pressure and enhances baroreflex sensitivity in hypertensive patients. These effects appear potentially beneficial in the management of hypertension.”

     Ideally, a holistic approach to controlling hypertension is needed, combining conventional medicine, exercise, breathing and mediation, and diet:
  https://www.mercola.com/Downloads/bonus/high-blood-pressure/default.aspx