Hypertension or increased blood pressure is a major public health problem worldwide and constitutes a major part of (along with diabetes) of the global burden of non-communicable diseases. The prevalence and incidence of hypertension is increasing each year with about 1.57 billion people expected to develop hypertension by 2025.
Hypertension, also considered as a silent killer due to the tendency to present without much signs or symptoms, remains a major cause for mortality. A reduction of at least 5 mm Hg in the systolic Blood Pressure can decrease the risk of mortality due to stroke by 14% and mortality from cardiovascular diseases by as much as 9%.
A major part of the clinical management of hypertension focuses on pharmacological therapeutic agents and lifestyle changes. However, an adequate and sustained control of blood pressure is probably achieved in about 50% of subjects treated with medicines.
Dietary approaches to the management of hypertension (as adjuvant therapy) are gaining interest. The Dietary Approach to Stop Hypertension (DASH) is a well-known nutritional intervention for the prevention and non-pharmacological management of hypertension. DASH highlights the importance of an increased fruit and vegetable intake. Studies have reported that a significant part of the benefits of DASH come from the high inorganic nitrate content of some of the food products included as part of the DASH diet.
Dietary Nitrates have become popular in recent years due to their reported cardio protective and ergogenic properties. Dietary inorganic Nitrates are absorbed rapidly in the proximal part of the small intestine and have 100% bioavailability. Nearly one-fourth of the nitrates circulating in plasma are concentrated in the salivary glands and secreted into the mouth. They are then converted to nitrites in the mouth by commensal bacteria and swallowed. When they reach the stomach, they are absorbed directly or reduced to nitric oxide. Endogenously produced nitrites and nitric oxide are vasoprotective and lead to dilation or expansion of the blood vessels, thus leading to a decrease in blood pressure and improved cardiovascular function.
Vegetables are the major source for dietary nitrates (maybe 80% or more) with high contents available in red beetroot, spinach, celery, lettuce and green leafy vegetables.
Several studies have explored the potential for red beetroot to reduce blood pressure in humans.
What do we know from these studies?
A systematic review and meta-analysis of 16 trials conducted between 2006 and 2012 and including a total of 254 subjects reported that consumption of inorganic nitrate and beetroot juice was associated with greater changes in systolic BP (-4.4 mm Hg) than diastolic BP (-1.1mm Hg). The Meta regression showed an association of daily dose of inorganic nitrates with the changes in systolic BP.
A placebo controlled randomized clinical trial in a group of persons with hypertension reported a significant reduction in blood pressures with daily supplementation of dietary nitrates. They reported a mean reduction of clinic determined blood pressures by 7.7/2.4 mm Hg (Systolic/Diastolic), of 24 hour ambulatory pressures by 7.7/5.2 mm Hg, and home blood pressures by 8.1/3.8 mm Hg. They reported a significant improvement in vascular endothelial function and reduction in arterial stiffness. They reported good tolerance with the daily dose (250 ml) and did not report any side effects.
Another study looked at the effect of beetroot juice without any restriction of diet in a small sample of persons. The authors wanted to explore if the effects of beet root juice sustain when given to persons who partake a normal diet or a diet without strict restrictions to understand what may happen in a pragmatic, real life scenario. They reported a trend towards lowered blood pressure at 6 hours after drinking beet root juice with the reduction (nearly 4-5 mm Hg of systolic blood pressure) being significant in men.
Another study reported that the ingestion of nitrate rich beetroot juice and spinach beverage effectively increased plasma nitrate and nitrite concentrations and lowered blood pressure to a greater extent than sodium nitrate. They showed that nitrate rich vegetables can be effective dietary nitrate supplements.
Another randomized clinical trial explored if increased dietary nitrate intake by ingestion of beetroot juice for a week will lower blood pressures in persons treated for hypertension. The authors reported a 3 fold increase in plasma nitrite and nitrates, a 7 fold increase in salivary nitrites, an 8 fold increase in salivary nitrate and a 4 fold increase in both urinary nitrite and nitrates. However, the authors did not find a significant change in blood pressures (24 hours ambulatory and home blood pressures) with a 1 week ingestion of beetroot juice.
How do we summarize these?
At this point, the use of dietary nitrate rich diets shows promise and has to be evaluated further in larger trials. Most studies report an effect on men and do not provide much data for any effect on women. Several studies use healthy volunteers and the effects on a diverse population (in terms of age, risk factors, degrees of hypertension and gender etc) require further study. A larger data pool through multiple larger studies can provide greater evidence.
If you are a physician
- You may want to consider including a dietary supplement of nitrate rich vegetables to the management regime of your patients
- Document results and explore if this supplementation may lead to the reduction in the number, dose and frequency of medicines they need
- You may want to consider initiating studies looking at various effects of nitrate rich dietary supplements on blood pressure and long term consequences of blood pressure.
If you are a policy maker
- You may want to encourage further research on dietary supplements.
- Hypertension is a major public health problem in India. Considering that a significant population of India may face difficulty in accessing and affording medicines, a non-pharmacologic approach can be very beneficial. (Although the cost of vegetables are indeed sometimes higher than medicines!)
- The cardio protective benefits may also be leveraged into a low cost preventive health program that can target an at risk younger age population.
- However, this will need further studies to develop a robust pool of evidence on effectiveness and long term consequences.
As an individual, this intrigued me and I did a study on myself. I took 250 ml of Cold Pressed Red Beet root juice daily morning between 6-8 am for one week. I noted down my systolic and diastolic blood pressure (Using a digital machine, OMRON healthcare) for three consecutive days prior to this (baseline and at 1 hour intervals for 3 hours) to determine a baseline value and understand what may be my normal hourly variation. I took four readings each time and averaged the last three readings.
On each day of ingestion of beet juice, I repeated the blood pressure measurements hourly for 3 hours after baseline. I did not alter any of my daily routines (including my attempts at exercise, diet or daily routine including hours of sleep).
I found a mean reduction of systolic BP by 9.5 units (SD 5.4) and diastolic BP by 6.25 units (SD 7.36) at 3 hours after drinking beet root juice.
I measured my baseline blood pressures daily in the second week (without drinking beetroot juice) and found a mean reduction of my systolic BP by 7 units and diastolic BP by 3 units (reduction from the mean baseline values before I started drinking beet root juice).
What does this mean?
It just means that drinking beet root juice brought about a reduction in my systolic and diastolic blood pressures. I must caution, there may be other reasons for this reduction as well, however, considering that I did not alter any other routine, this reduction may be attributed to beet (and i am not fond of beet- had to squeeze eyes hard to finish my dose- so not really biased towards it). What worked for me need not work for everyone but i thought the results were consistent with the results of other studies.
Does this mean that you may benefit if you are a healthy individual, a person who may be at risk for hypertension, or a person with hypertension by taking a diet rich in dietary nitrates?
- Studies indicate a benefit from dietary nitrate consumption (although more studies will be helpful to develop more robust evidence).
- Studies do not report major side effects
- Red beet root and spinach are commonly available vegetables
- I recommend that you speak to your physician about including dietary nitrates as part of your regular diet. Your doctor can monitor the changes in the blood pressure and then advise on continuing the diet or even adjusting the dose of medicines.
Selected reference articles