Functional Nutrition for Hypertension

What is hypertension?

Hypertension (another name for high blood pressure) is a common condition that significantly increases the risk for cardiovascular disease (1).

What is blood pressure?

Blood pressure is the force of blood pushing against the walls of arteries (23).

It is measured in millimeters of mercury (mmHg) and is written as the systolic pressure over the diastolic pressure. 

Systolic blood pressure is the amount of pressure exerted when the heart beats, while diastolic blood pressure refers to the amount of pressure when the heart is resting between beats.

How common is hypertension?

In the United States, the overall prevalence of hypertension in adults is 29% (4).

However, prevalence does increase significantly with age. Nearly 63% of older adults 60 years of age or older have a diagnosis of hypertension (4).

What are the symptoms?

Hypertension is considered to be an asymptomatic condition, meaning that it produces no symptoms (5).

Many patients experience symptoms that they attribute to hypertension, such as headaches, dizziness, hot flashes, and mood swings (6).

However, there is no evidence that these symptoms are actually caused by high blood pressure in most people.

A small number of patients (1-2%) may experience a hypertensive crisis, which is a severe and sudden increase in blood pressure that can lead to organ damage (7).

These patients may experience symptoms including headache, dizziness, altered mental status, shortness of breath, chest pain, vomiting, and changes in vision.

What causes hypertension?

Most patients (90-95%) have primary (or essential) hypertension, which has no known cause (1). 

It has been theorized that some of the following factors might increase the risk for primary hypertension (891011121314):

  • Genetics
  • Gut dysbiosis
  • High salt diet
  • Inflammation
  • Mercury exposure
  • Obesity
  • Oxidative stress
  • Pollution (air and noise)
  • Sedentary lifestyle
  • Smoking
  • Stress
  • Vitamin D deficiency

Around 5-10% of patients have what is called secondary hypertension, because there is a known cause (15).

Causes of secondary hypertension include the following (1516):

1. Renal causes

  • Chronic kidney disease
  • Renal artery stenosis

2. Endocrine causes

  • Cushing syndrome
  • Hyperparathyroidism
  • Hyperthyroidism
  • Hypothyroidism
  • Pheochromocytoma
  • Primary aldosteronism

3. Vascular causes

  • Coarctation (narrowing) of the aorta

4. Drug related causes (171819)

  • Amphetamines
  • Antidepressants (MAOIs, SNRIs, TCAs)
  • Antipsychotics (clozapine, olanzapine)
  • Caffeine
  • Decongestants (phenylephrine, pseudoephedrine)
  • Herbal supplements (ephedra, ginseng, licorice, St. John’s wort, yohimbe)
  • Immunosuppressants (cyclosporine)
  • NSAIDs
  • Recreational drugs (cocaine, methamphetamine, etc.)
  • Sex hormones (oral contraceptives, replacement therapy)
  • Systemic corticosteroids (methylprednisolone, prednisone)

5. Other causes

  • Obstructive sleep apnea
  • Pregnancy
  • Scleroderma

What are the potential consequences of hypertension?

The following may be consequences of uncontrolled hypertension:

1. Cardiovascular disease

Uncontrolled hypertension results in a twofold to threefold increase in the risk of dying from cardiovascular disease (20).

High blood pressure can cause enlargement of the left ventricle of the heart and narrowing of blood vessels, which can contribute to the development of coronary artery disease and heart failure (2122).

2. Chronic kidney disease

Hypertension is the second leading cause of chronic kidney disease, a condition in which the kidneys slowly lose the ability to filter waste from the blood (23).

Chronic high blood pressure can damage the small blood vessels in the glomeruli (the filtration units of the kidney), leading to a gradual loss of kidney function (24).

3. Dementia

Chronic high blood pressure causes blood vessels to become stiff, which can impair the brain’s ability to dispose of amyloid peptides (25).

The accumulation of amyloid plaques is thought to contribute to the development of Alzheimer’s disease (26).

4. Vision loss

Hypertensive retinopathy occurs when the small blood vessels in the retina are damaged by high blood pressure, which can eventually lead to impaired vision (27).

Approximately 10% of adults without diabetes (another risk factor for retinopathy) have signs of mild hypertensive retinopathy (28).

The risk for developing this condition depends on the degree and duration of hypertension (29).

5. Sexual dysfunction

An estimated 30% of men with hypertension experience erectile dysfunction (ED) (30).

Over time, high blood pressure can damage the blood vessels in the penis, resulting in decreased blood supply and difficulty achieving or maintaining an erection (3132).

Treatment for hypertension lowers the incidence of erectile dysfunction if blood pressure is tightly controlled (3334).

6. Osteoporosis

Hypertension is associated with lower bone mineral density (BMD) scores and higher risk of osteoporotic fractures (3536).

The exact mechanism for this effect is unclear, but scientists believe it may be related to changes in calcium metabolism caused by hypertension (36).

How is it diagnosed?

The following criteria are used to categorize blood pressure measurements (37):

  • Normal: <120 mm Hg systolic BP and <80 mm Hg diastolic BP
  • Elevated: 120-129 mm Hg systolic BP and <80 mm Hg diastolic BP
  • Stage 1 hypertension: 130-139 mmHg systolic BP or 80-89 mm Hg diastolic BP
  • Stage 2 hypertension: >/=140 mm Hg systolic BP or >/=90 mm Hg diastolic BP

What is the goal of treatment?

A blood pressure of less than 130/80 mmHg is recommended as a goal for patients with hypertension (37).

Which medications are used to treat hypertension?

The following are some of the most common medications used in the treatment of hypertension (37):

1. Diuretics

There are three types of diuretics: thiazide (most common), loop, and potassium-sparing.

Diuretics lower blood pressure by increasing sodium and fluid excretion, which leads to reduced blood volume and cardiac output (38).

2. Calcium channel blockers (CCBs)

CCBs block calcium from entering cells in the heart and blood vessels, which results in decreased muscle contraction and allows blood vessels to relax, leading to decreased blood pressure (39).

Any drugs that end with the suffix “-dipine” are calcium channel blockers.

3. Angiotensin-converting enzyme (ACE) inhibitors 

ACE is the enzyme that helps convert angiotensin I to angiotensin II (a hormone that increases blood pressure by causing blood vessels to constrict) (4041).

ACE inhibitors prevent this conversion, allowing blood vessels to relax and lowering blood pressure (40).

Any drugs that end with the suffix “-pril” are ACE inhibitors.

4. Angiotensin II receptor blockers (ARBs)

Similar to ACE inhibitors, ARBs work by preventing angiotensin II from exerting its effects on blood vessels (42).

ARBs prevent angiotensin II from binding to receptors on the heart and blood vessels, thereby allowing them to relax and lowering blood pressure.

Any drugs that end with the suffix “-sartan” are ARBs.

5. Beta-blockers

Beta-blockers (also called beta-adrenergic blocking agents) prevent norepinephrine and epinephrine from binding to beta receptors on the heart and blood vessels (43).

This leads to a slower heartbeat, dilated blood vessels, and lower blood pressure.

Any drugs that end with the suffix “-olol” are beta-blockers.

What diets can help lower blood pressure?

The following diets may be recommended for hypertension:

1. The DASH diet

The DASH (Dietary Approaches to Stop Hypertension) diet originated in the 1990s when researchers discovered that dietary intervention alone could lower blood pressure significantly (44).

Generally, the following number of daily servings from each food group are recommended based on a 2,000-calorie diet:

  • Vegetables: 4-5 servings per day
  • Fruits: 4-5 servings per day
  • Grains: 6-8 servings/day (mainly whole grains)
  • Dairy products: 2-3 servings per day (low-fat)
  • Lean meat, poultry, and fish: 6 one-ounce servings or fewer per day (limited red meat)
  • Nuts, seeds, and legumes: 4-5 servings per week
  • Fats and oils: 2-3 servings per day (mostly vegetable oils)
  • Sweets: 5 or fewer servings per week
  • Sodium intake should be limited to 2300 mg per day (or 1500 mg for a low-sodium version of the diet)

This diet is high in nutrients that are known to lower blood pressure: fiber, potassium, magnesium, and calcium (45).

There is strong evidence that the DASH diet lowers systolic blood pressure by 5-7 mmHg and diastolic blood pressure by 2-4 mmHg (4647).

The diet’s blood pressure-lowering effect is typically strongest in patients with hypertension (47).

A recent meta-analysis found that the DASH diet was the most effective diet for lowering blood pressure, compared to 12 other diets (including the Mediterranean diet, vegetarian diet, and Paleo diet) (48).

However, in one study, a modified DASH diet (higher fat, lower carbohydrate) that included full-fat dairy products reduced blood pressure to the same extent as the standard DASH diet (49).

In patients who have the highest adherence to the DASH diet, stroke risk is reduced by 12% and coronary artery disease risk is reduced by 18% (5051).

2. Vegetarian and vegan diets

A large body of evidence shows that vegetarian diets are associated with overall lower blood pressure (52).

Several clinical trials have confirmed that consuming a vegetarian diet significantly reduces systolic (-4.8 mmHg) and diastolic BP (-2.2 mmHg) (52).

Vegan diets also lower blood pressure but are not more effective than less restrictive diets, such as the lacto-ovo vegetarian diet and the DASH diet (53).

3. The Mediterranean diet

There is limited evidence that a Mediterranean diet can reduce blood pressure in patients with hypertension.

A 2016 meta-analysis of six trials showed that a one-year Mediterranean diet significantly reduced systolic (-1.44 mmHg) and diastolic BP (-0.70 mmHg) in individuals with mild hypertension (54). 

4. Paleo diet?

A 2019 meta-analysis of 8 trials found that a paleo diet significantly reduced systolic (-4.24 mmHg) and diastolic BP (-2.95 mmHg) (55).

However, the authors pointed out that the evidence is not conclusive and more well-designed trials are needed.

Which foods or nutrients should be limited?

People with hypertension may want to monitor their intake of the following:

1. Sodium

The worldwide average sodium intake is 3600-4800 mg per day (56).

Several large health organizations have recommended that patients with hypertension reduce dietary sodium intake to <1500 mg per day (37).

They believe that excessive sodium can increase blood volume, stiffen arteries, and alter blood vessel function, all of which ultimately lead to elevated blood pressure (57).

A large meta-analysis found that reducing sodium intake by 1760 mg per day resulted in decreased systolic (-5.39 mmHg) and diastolic (-2.82 mmHg) BP in patients with hypertension (58).

However, evidence that low sodium diets actually reduce adverse health outcomes is conflicting (59606162).

In fact, several meta-analyses have found that BOTH low-sodium (<2600-3000 mg/day) and high-sodium (>5000-7000 mg/day) diets were associated with increased cardiovascular events and mortality rates (636465).

Still, an estimated 50-60% of patients with hypertension are considered “salt sensitive,” meaning that their blood pressure increases dramatically in response to higher sodium intake (56).

Approximately 70% of the sodium in a standard American diet comes from processed foods and eating out, so simply cooking from scratch at home more often can significantly reduce overall sodium intake (66).

2. Alcohol

Alcohol can raise blood pressure by 1 mmHg for every 10 grams consumed (67).

There are several potential mechanisms for this effect, including increased cortisol and angiotensin II levels (68)

Women and men with elevated BP or hypertension are advised to limit alcohol intake to no more than 1 or 2 drinks per day, respectively (37).

3. Added sugar

Added sugar (especially from sugar-sweetened beverages) is associated with higher blood pressure (6970).

Increasing consumption of sugar-sweetened beverages by just 1 serving per day is linked with increases in systolic (+1.6 mmHg) and diastolic BP (+1.1 mmHg) (71).

It is thought that high fructose intake increases uric acid levels, which elevates blood pressure by reducing nitric oxide (a vasodilator) (72).

The American Heart Association recommends no more than 100 calories (25 grams or 6 teaspoons) from added sugars per day for women and no more than 150 calories (37.5 grams or 9 teaspoons) per day from added sugar for men (73).

4. Caffeine?

Caffeine intake of 200-300 mg (equivalent to 2-3 cups of coffee) increases both systolic (+8.1 mmHg) and diastolic BP (+5.7 mmHg) for at least 3 hours after consumption (74).

It’s unclear exactly why this occurs, but it may be related to increased epinephrine (adrenaline) levels, which is known to increase blood pressure (7576).

It is recommended that caffeine intake be limited to <300 mg/day in order to prevent or manage high blood pressure (37).

However, habitual coffee consumption (>/= 2 weeks) is not associated with elevated blood pressure, which may be explained by increased caffeine tolerance (74).

Which foods help lower blood pressure?

The following foods may help lower blood pressure naturally:

1. Hibiscus tea

Hibiscus is an antioxidant-rich tropical plant that is often used to make tea (sometimes called sour tea) (77).

Strong evidence supports the consumption of hibiscus tea (2-3 cups/day for 1 month) for lowering systolic BP (-7.58 mmHg) and diastolic BP (-3.53 mmHg) in patients with hypertension (777879)

The exact mechanism for this effect is not well understood, but some believe it may be due to the high anthocyanin content of hibiscus (7780).

2. Cocoa

There is strong evidence showing that consumption of cocoa products (1.4 to 105 grams/day for 2-18 weeks) reduces systolic BP (-1.76 mmHg) and diastolic BP (-1.76 mmHg) in adults with or without hypertension (81).

Flavanols found in dark chocolate and cocoa products are thought to lower blood pressure by stimulating the production of nitric oxide, which acts as a vasodilator (81).

It is important to note, however, that milk chocolate and Dutch-process cocoa contain much fewer blood pressure-lowering flavanols.

3. Flaxseeds

Scientists believe that lignans (a type of polyphenol) found in flaxseeds may help to lower blood pressure by calming inflammation (82).

Strong evidence shows that supplementation with ground flaxseed (4-8 tablespoons/day) for at least 1 month reduces systolic (-2.85 mmHg) and diastolic BP (-2.39 mmHg) (83).

This effect was strongest in individuals with severe hypertension who supplemented for at least 3 months (8283).

However, more research is needed to determine whether lower doses (<4 tablespoons) might have the same effect.

4. Pomegranate juice

Pomegranate juice is rich in polyphenols, including flavonoids, which may lower blood pressure by reducing oxidative stress and improving endothelial function (84).

Evidence from 8 trials suggests that pomegranate juice consumption (0.5-2 cups) significantly reduces both systolic (-4.96 mmHg) and diastolic BP (-2.01 mmHg) regardless of duration (84).

5. Beet juice

Beet juice is especially high in nitrates, which are converted to nitric oxide (a vasodilator) in the body (85).

There is some evidence that drinking beetroot juice (0.5-2 cups/day) for up to 2 weeks lowers blood pressure significantly (-4.4 mmHg systolic BP and -1.1 mmHg diastolic BP) (85).

6. Nuts

Higher nut consumption is linked with lower incidence of hypertension (86).

A meta-analysis of 21 trials found that nut consumption significantly reduced systolic blood pressure (-1.29 mmHg) in adults without diabetes (87).

However, when researchers looked at the effects of specific nuts, they discovered that only pistachios and mixed nuts significantly lowered blood pressure (87).

The mechanism for this effect is unclear, but some scientists believe that the magnesium found in nuts reduces oxidative stress and improves vascular function (88).

7. Berries?

There is limited evidence that regularly consuming berry powder or whole berries (including cranberries, blueberries, bilberries, raspberries, and elderberries) lowers blood pressure (89).

It is thought that berries might increase nitric oxide production, which causes blood vessels to relax and dilate, decreasing pressure (90).

However, the evidence is conflicting, as a recent meta-analysis found that blueberries had no significant effect on blood pressure (91).

More research that focuses exclusively on patients with hypertension is needed.

Which nutrients could be beneficial for hypertension?

The following vitamins and minerals may help regulate blood pressure naturally:

1. Potassium

There is strong evidence showing that potassium supplementation to achieve a total intake of >/=3500 mg per day significantly reduces systolic (-4.48 mmHg) and diastolic BP (-2.96 mmHg) (94).

These effects were most pronounced in participants who had higher (>/=4 grams/day) sodium intake (94).

A potassium intake of 3500-5000 mg/day (preferably through diet) is recommended for patients with hypertension (37).

Research suggests that potassium deficiency increases blood pressure by stimulating salt reabsorption in the kidneys (95).

In fact, using the sodium-to-potassium ratio (based on how much is excreted in the urine) can help determine cardiovascular risk in patients with hypertension (96).

A lower ratio (<1.0), which indicates higher potassium intake and lower sodium intake, is associated with decreased blood pressure and cardiovascular disease risk.

2. Magnesium

Dietary magnesium intake is associated with a 5% reduction in hypertension risk for each 100 mg consumed per day (97).

In addition, a 2016 meta-analysis found that magnesium supplementation (368 mg/day) for 3 months significantly reduced systolic (-2.0 mmHg) and diastolic BP (-1.78 mmHg) (98).

Magnesium helps to lower blood pressure by acting as a natural calcium channel blocker, increasing nitric oxide production, and improving endothelial function (99).

3. Vitamin C

Research suggests that vitamin C may enhance nitric oxide production and improve endothelial function (100).

A recent meta-analysis showed a reduction in both systolic (-4.09 mmHg) and diastolic BP (-2.30 mmHg) with vitamin C supplementation (300-1000 mg/day) for 4-24 weeks in subjects with hypertension (101).

4. Folate

Scientists believe that folate might improve blood pressure by reducing homocysteine, which can contribute to endothelial dysfunction (102).

Evidence from a 2009 meta-analysis shows a small decrease in systolic BP (-2.03 mmHg) with folic acid supplementation (5000 mcg/day) for at least 6 weeks (103).

5. Calcium?

Calcium regulates blood pressure via several mechanisms, including the modification of intracellular calcium in smooth muscle cells of blood vessels (104).

Dietary calcium intake is associated with a 7% reduction in relative risk for hypertension for each 500 mg per day (105).

However, more research is needed to confirm whether calcium supplementation could be effective as a treatment rather than a preventative measure for hypertension (106). 

6. Vitamin D?

Vitamin D might be involved in blood pressure regulation through the modulation of the renin-angiotensin-aldosterone system (RAAS) (107).

Low vitamin D status is associated with a 12% increased relative risk for hypertension for every 10 ng/mL reduction below optimal serum 25(OH)D levels (108).

There is evidence that vitamin D supplementation (5000 IU/day) for 8 weeks reduces diastolic blood pressure (-1.65 mmHg) with no effect on systolic blood pressure in vitamin D-deficient subjects (109).

More research is needed to determine whether these effects are similar in patients with hypertension.

7. Omega-3 fatty acids?

Omega-3 fatty acids are known to provide protection against cardiovascular disease, which might be due to decreased blood pressure (110).

There are many potential mechanisms for this, such as an ability to reduce ACE activity and inhibit angiotensin II formation (111).

Evidence suggests that high doses of omega-3 fatty acids (>/=3 g/day) result in a small decrease in systolic blood pressure in older and hypertensive subjects (112). 

However, more research is needed, because studies have produced conflicting results (112). 

8. CoQ10?

Coenzyme Q10 (CoQ10) is an antioxidant naturally present in humans, and it may lower blood pressure by preserving nitric oxide and reducing peripheral resistance (113).

A 2007 meta-analysis showed reductions in systolic (-16.6 mmHg) and diastolic blood pressure (-8.2 mmHg) after CoQ10 supplementation (34-225 mg/day) in subjects with hypertension (114).

However, findings are mixed, as a newer review found no clinically significant effects on blood pressure (115).

9. Polyphenols/flavonoids

Flavonoids are a group of polyphenols found in a wide variety of foods, including fruits, vegetables, cocoa, tea, and wine (116117).

High flavonoid intake is associated with a lower risk of developing hypertension (118).

They are thought to lower blood pressure by increasing nitric oxide availability, reducing oxidative stress within blood vessels, and altering vascular function (116).

Do any other supplements help?

The following supplements may also help lower blood pressure:

1. Garlic extract

Sulfide compounds found in garlic enhance nitric oxide regulation, which allows for vasodilation and lowers blood pressure (119).

A 2020 meta-analysis of 12 trials showed that garlic extract supplements reduced systolic BP by 8.3 mmHg and diastolic BP by 5.5 mmHg, which is similar to standard anti-hypertensive medications (120).

More research is needed to determine the optimal dose and duration of treatment, but doses studied range from 240-2400 mg per day for at least 8-12 weeks (121).

There is also evidence that underlying vitamin deficiencies (particularly vitamin B12) may reduce the effectiveness of garlic on blood pressure (120).

2. Psyllium

Psyllium, a popular soluble fiber supplement, may help treat hypertension by reducing insulin resistance, which is known to cause endothelial dysfunction (122).

A 2020 meta-analysis of 11 trials showed a significant reduction in systolic blood pressure (-2.04 mmHg) with psyllium supplementation (10-15 g/day) for at least 8 weeks (122).

The blood pressure-lowering effect was strongest in participants with higher baseline blood pressure measurements. 

3. Melatonin

Melatonin is a hormone produced in the pineal gland of the brain that regulates the sleep-wake cycle (123).

A recent meta-analysis of 5 trials found a significant reduction in both systolic blood pressure (-3.43 mmHg) and diastolic blood pressure (-3.33 mmHg) after supplementation with melatonin (5 mg/day in the evening) for 8 weeks (124).

The exact mechanism is unclear, but melatonin may lower blood pressure by decreasing norepinephrine and dopamine levels (124).

4. Taurine

Taurine, an amino acid naturally found in food, reduces blood pressure by suppressing angiotensin II, a hormone that induces vasoconstriction (125).

A 2018 meta-analysis of 7 trials found that taurine supplementation (1-6 g/day) for up to 12 weeks resulted in an average reduction of 3 mmHg for both systolic and diastolic blood pressure (125). 

However, these were very small trials with a total of 103 participants, so more research is needed.

5. Dried bonito?

Bonito is a popular variety of tuna (also known as skipjack tuna) that is smoked, dried, and used as a broth base ingredient in Japan (126).

One study showed a significant decrease in systolic blood pressure (-6.4 mmHg) after one month of bonito broth supplementation (125 mL/day) (126).

Proteins found in bonito may have ACE-inhibiting properties that help to lower blood pressure (127).

6. Grape seed extract?

A 2016 trial found that supplementation with grape seed extract (150 mg twice daily) for 6 weeks reduced systolic BP (5-6%) and diastolic BP (4-7%) in patients with prehypertension (128).

The researchers suggested that flavonoids found in grape seed extract were responsible for its blood-pressure-lowering effects (128).

However, other studies have produced conflicting results (129130).

What other lifestyle changes are recommended?

The following lifestyle changes can also help lower blood pressure:

1. Regular exercise

A recent meta-analysis of 391 trials found that regular exercise was just as effective as anti-hypertensive drugs for lowering blood pressure (131).

Patients with hypertension are advised to participate in 90-150 minutes of exercise per week in order to lower blood pressure (37).

Consistent aerobic exercise decreases systolic blood pressure by 2-5 mmHg and diastolic blood pressure by 1-4 mmHg on average (132).

Dynamic resistance training probably lowers blood pressure to a similar degree, but more research is needed (133).

Practicing yoga (5 sessions per week, 60 minutes per session) also lowers blood pressure (-5.0 mmHg systolic BP, -3.9 mmHg diastolic BP) (134). 

2. Stress reduction

High levels of psychosocial stress are associated with 240% increase in hypertension risk (135) .

Mindfulness-based stress reduction (MSBR) is a program that uses meditation to teach participants to cope with emotions (136).

There is some evidence that MBSR and other stress-reduction techniques implemented for at least 24 weeks might lower blood pressure in patients with hypertension, but more research is needed (136137).

Which anti-hypertensive drugs are linked to nutrient deficiencies?

Loop and thiazide diuretics are known to cause deficiencies in potassium, zinc, magnesium, and thiamin, and have also been linked with an increased risk of insulin resistance (138139140).

ACE inhibitors, especially captopril, may increase the risk of zinc deficiency (138).

Calcium channel blockers have been linked with possible folate deficiency (138).

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