By Dr. Mercola
There are many reasons to feast on asparagus, like its impressive concentration of vitamin K and B vitamins, including folate. Folate helps your body make dopamine, serotonin, and norepinephrine, which is why asparagus is a "feel-good" veggie that may support your mood.
Asparagus is also high in glutathione, an important anti-carcinogen, and contains rutin, which protects small blood vessels from rupturing and may protect against the damaging effects of radiation. Asparagus is also a good source of vitamins A, C and E, potassium, and zinc.
In addition, asparagus is a veritable superfood for digestive health, featuring both insoluble and soluble fiber along with inulin, a prebiotic that acts as food for beneficial bacteria in your gut.
But even beyond adding valuable nutrition to your diet, another reason to eat asparagus regularly has to do with its effect on your heart health, and specifically its beneficial role in fighting high blood pressure.
Asparagus May Help Lower High Blood Pressure
Angiotensin-converting enzyme (ACE) inhibitors are commonly prescribed to treat high blood pressure. They work by blocking an enzyme needed to produce a substance that narrows blood vessels. In turn, ACE inhibitor drugs help your blood vessels relax and widen, which allows blood to flow through easier and lowers blood pressure.1
The problem with ACE inhibitors is their potential for serious side effects, which includes sudden kidney failure that's fatal in 30 percent of those affected.2 Increased potassium levels, which may lead to serious heart problems, can also occur, as can decrease in sexual function, dizziness, headache, fatigue, liver damage, and depression.3
Recently, however, researchers uncovered a natural ACE inhibitor in asparagus, and it appears useful for lowering blood pressure. The study revealed a new sulfur-containing metabolite known as asparaptine in asparagus spears. The compound acted as a "new ACE inhibitor," according to the study.4
In addition, previous research published in the Journal of Agricultural and Food Chemistry showed that when rats were fed a diet containing 5 percent asparagus for 10 weeks, their systolic blood pressure (the top number) dropped significantly compared to rats fed a non-asparagus diet.5
The researchers also noted decreased activity of the ACE enzyme, and believe another compound in asparagus, 2"-hydroxynicotianamine, may act as an ACE inhibitor as well.6 The asparagus group also had an increased creatinine clearance rate, which is a measure of how well the kidneys are working.
A study in humans also revealed that consuming powdered asparagus (six grams daily for 10 weeks) resulted in significant reductions in blood pressure among 28 healthy volunteers.7 As noted in the Epoch Times:8
"The research suggests that asparagus has an overall effect of benefitting the kidneys and lowering blood pressure for cases of hypertension."
Blueberries May Also Benefit Your Blood Pressure
If you are diagnosed with high blood pressure, dietary strategies will be crucial to controlling your levels. And if you have pre-hypertension, you can typically stop its progression and regain healthy levels just by changing the way you eat.
In addition to eating asparagus, a daily dose of blueberries may also lower your blood pressure. The study involved postmenopausal women, who have an especially high rate of hypertension and often develop arterial stiffness, increasing their risk of heart disease considerably.
The women, who had either pre-hypertension or hypertension, received freeze-dried blueberry powder – an amount equivalent to about one cup of fresh blueberries – or a placebo powder daily for eight weeks.
At the end of the study, systolic blood pressure dropped by 5 percent and diastolic blood pressure (the bottom number) dropped by more than 6 percent in the blueberry group, while no significant changes occurred in the placebo group.
Measurements of nitric oxide (NO) were also significantly increased in the blueberry group, with no such change in the control group. Nitric oxide helps your blood vessels maintain their elasticity and also dilates your blood vessels, thereby reducing your blood pressure. According to the study authors:
"Daily blueberry consumption may reduce blood pressure and arterial stiffness, which may be due, in part, to increased nitric oxide production."
Dietary Culprit #1 for High Blood Pressure? Sugar
One of the primary underlying causes of high blood pressure is related to your body producing too much insulin and leptin in response to a high-carbohydrate (i.e. high sugar) and processed food diet. As your insulin and leptin levels rise, it causes your blood pressure to increase. Eventually, you may become insulin and/or leptin resistant.
As explained by Dr. Rosedale, insulin stores magnesium, but if your insulin receptors are blunted and your cells grow resistant to insulin, you can't store magnesium so it passes out of your body through urination. Magnesium stored in your cells relaxes muscles.
If your magnesium level is too low, your blood vessels will be unable to fully relax, and this constriction raises your blood pressure. Fructose also elevates uric acid, which drives up your blood pressure by inhibiting the nitric oxide in your blood vessels. (Uric acid is a byproduct of fructose metabolism. In fact, fructose typically generates uric acid within minutes of ingestion.)
Nitric oxide helps your vessels maintain their elasticity, so nitric oxide suppression leads to increases in blood pressure. So any program adapted to address high blood pressure needs to help normalize both your insulin/leptin sensitivity and uric acid level.
As it turns out, by eliminating excess sugar/fructose from your diet, you can address all three issues (insulin, leptin, and uric acid) at once. As a standard recommendation, I recommend keeping your total fructose consumption below 25 grams per day, or to 15 grams or less per day if you have high blood pressure (or diabetes, heart disease, or other chronic disease).
What Should Your Diet Look Like if You Have High Blood Pressure?
One out of every three US adults has high blood pressure (hypertension),9 while another 59 million Americans have pre-hypertension10 (which means you may soon develop full-blown hypertension). This is an incredibly common problem, but you don't have to become just one more statistic.
While functional foods like asparagus and blueberries are certainly healthy, they are not a first-line treatment for a health problem like high blood pressure. You'll need to address its underlying causes as well if you want to overcome this condition.
Avoiding processed foods (due to their being high in sugar/fructose, grains, trans fat and other damaged fats and processed salt) is my number one recommendation if you have high blood pressure. Instead, make whole, ideally organic, foods the focus of your diet.
As you reduce processed foods, and other sources of non-vegetable carbs, from your diet, you'll want to replace them with healthy fat. Sources of healthy fats to add to your diet include:
Avocados Butter made from raw, grass-fed organic milk Raw dairy Organic pastured egg yolks Coconuts and coconut oil Unheated organic nut oils Raw nuts, such as pecans and macadamia, which are low in protein and high in healthy fats Grass-fed meats or pasture raised poultry
My Top-Recommended Strategies to Prevent Hypertension
It's not only your diet that matters for healthy blood pressure… a comprehensive fitness program is another strategy that can improve your blood pressure and heart health on multiple levels (such as improving your insulin sensitivity).
To reap the greatest rewards, I strongly suggest including high-intensity interval exercises in your routine. You'll also want to include weight training. When you work individual muscle groups you increase blood flow to those muscles, and good blood flow will increase your insulin sensitivity. If you want to kill several birds with one stone, exercise barefoot outdoors on sunny days.
Not only will you get much-needed sunshine to promote production of heart-healthy vitamin D, but bright daylight sun exposure will also help maintain a healthy circadian clock, which will help you sleep better. Poor sleep is yet another oft-ignored factor that can cause resistant hypertension. Going barefoot, meanwhile, will help you ground to the earth. Experiments show that walking barefoot outside — also referred to as Earthing or grounding — improves blood viscosity and blood flow, which help regulate blood pressure.
Keep in mind that, in most cases, high blood pressure is a condition that can be managed and oftentimes reversed with natural lifestyle changes. I encourage you to read through my full list of strategies to prevent and treat hypertension, however, below you'll find some additional highlights.
- Skip breakfast: Research shows that intermittent fasting helps fight obesity and type 2 diabetes, both of which are risk factors for high blood pressure. Your body is most sensitive to insulin and leptin after a period of fasting. While there are many types of fasting regimens, one of the easiest to comply with is an eating schedule where you limit your eating to a specific, narrow window of time each day. I typically recommend starting out by skipping breakfast, and making lunch your first meal of the day until you resolve insulin resistance, then you can eat breakfast if your fasting insulin levels remain normal.
- Optimize your vitamin D levels: Arterial stiffness (atherosclerosis) is a driving factor for high blood pressure. As your blood travels from your heart, cells in the wall of your aorta, called baroreceptors, sense the pressure load, and signal your nervous system to either raise or lower the pressure. However, the stiffer your arteries are, the more insensitive your baroreceptors become, and the less efficient they become at sending the appropriate signals. Vitamin D deficiency is, in turn, linked to stiff arteries, which is why optimizing your levels is so important.
- Address your stress: The link between stress and hypertension is well documented. Suppressed negative emotions such as fear, anger, and sadness can severely limit your ability to cope with the unavoidable every day stresses of life. It's not the stressful events themselves that are harmful, but your lack of ability to cope. I recommend the Emotional Freedom Technique (EFT) to transform your suppressed, negative emotions and relieve stress.
- Normalize your omega 6:3 ratio: Most Americans get too much omega-6 in their diet and far too little omega-3. Consuming omega-3 fats will help re-sensitize your insulin receptors if you suffer from insulin resistance. Omega-6 fats are found in corn, soy, canola, safflower, and sunflower oil. If you're consuming a lot of these oils, you'll want to avoid or limit them. For omega-3s, your best bet is to find a safe source of fish, or if this proves too difficult or expensive, supplement with a high-quality krill oil, which has been found to be 48 times more potent than fish oil.
- Optimize your gut flora: Compared to a placebo, people with high blood pressure who consumed probiotics lowered systolic blood pressure (the top number) by 3.56 mm Hg and diastolic blood pressure (the bottom number) by 2.38 mm Hg.11 The best way to optimize your gut flora is by avoiding sugar and processed foods and including naturally fermented foods in your diet, which may contain about 100 times the amount of bacteria in a bottle of high-potency probiotics. Using fermented foods with a starter culture like Kinetic Culture will also add therapeutic levels of important nutrients like vitamin K2.
- Maintain an optimal sodium-potassium ratio: As mentioned, an imbalanced ratio may lead to hypertension. To ensure yours is optimal, ditch all processed foods, which are very high in processed salt and low in potassium and other essential nutrients. Instead, eat a diet of whole, unprocessed foods, ideally organically and locally-grown to ensure optimal nutrient content. This type of diet will naturally provide much larger amounts of potassium in relation to sodium.
- Eliminate caffeine: The connection between coffee consumption and high blood pressure is not well understood, but there is ample evidence to indicate that if you have hypertension, coffee and other caffeinated drinks and foods may exacerbate your condition.
- Vitamins C and E: Studies indicate that vitamins C and E may be helpful in lowering blood pressure. If you're eating a whole-food diet, you should be getting sufficient amounts of these nutrients through your diet alone. If you decide you need a supplement, make sure to take a natural (not synthetic) form of vitamin E. You can tell what you're buying by carefully reading the label. Natural vitamin E is always listed as the "d-" form (d-alpha-tocopherol, d-beta-tocopherol, etc.) Synthetic vitamin E is listed as "dl-" forms.
- Olive leaf extract: In one 2008 study, supplementing with 1,000 mg of olive leaf extract daily over eight weeks caused a significant dip in both blood pressure and LDL ("bad") cholesterol in people with borderline hypertension. If you want to incorporate olive leaves as a natural adjunct to a nutritionally sound diet, look for fresh leaf liquid extracts for maximum synergistic potency. You can also prepare your own olive leaf tea by placing a large teaspoon of dried olive leaves in a tea ball or herb sack. Place it in about two quarts of boiling water and let it steep for three to 10 minutes. The tea should be a medium amber color when done.
- Quick tricks: Increasing nitric oxide in your blood can open constricted blood vessels and lower your blood pressure. Methods for increasing the compound include taking a warm bath, breathing in and out through one nostril (close off the other nostril and your mouth), and eating bitter melon, rich in amino acids and vitamin C.