Many foods can affect blood pressure -- some (like the weak stimulants found in coffee and tea) for a short period of time, others (like salt) over a longer period. Because a healthy diet has been shown to improve blood pressure health, knowing which foods to incorporate into your meal plans -- and which to avoid -- can help you make better dietary decisions. Each of the foods listed below has been shown to influence blood pressure, and understanding the effects of each is essential to a well-balanced, well-informed diet plan.
1. SaltThough there is disagreement about the precise role that salt plays in high blood pressure, there is no question that blood pressure and salt intake are related. Strong evidence suggests that some people may be abnormally sensitive to salt, and that salt consumption may place them at higher risk for many cardiovascular problems. While the details have yet to be worked out, being vigilant about your salt intake may help to lower your risk of high blood pressure or make existing high blood pressure easier to control.
2. CaffeineCaffeine is a stimulant. It excites the central nervous system and increases heart rate, metabolic rate, and blood pressure. These effects, though, are only temporary, and the long-term effects of caffeine consumption may surprise you. In landmark studies, the consumption of caffeine has been linked to higher blood pressure only in certain circumstances. Interestingly, it appears that the people who experience the most blood pressure risk from drinking caffeine are those who only consume small amounts. People with higher consumption seem to acquire some resistance to caffeine's stimulant effects.
3. AlcoholStudies have shown that drinking “moderate” amounts of alcohol seems to protect against high blood pressure, heart attack, and other cardiovascular diseases. It is thought that the alcohol affects the walls of blood vessels, altering their elasticity and changing how they respond to certain “stress” messages carried by hormones. The combination of these two effects increases blood vessel compliance, resulting in lowered average blood pressure and decreased cardiac work. In excessive amounts, though, alcohol has exactly the opposite effects – it increases blood vessel stiffness, raises the overall level of metabolic “stress,” and places higher demands on the heart.
4. Folic AcidFolic acid, the manmade version of vitamin B9, is found in many prepackaged foods like bread, cereals, and flour. Strong evidence exists that folic acid can help lower blood pressure (and prevent the onset of high blood pressure) if consumed in adequate amounts (about 800 micrograms per day). The catch? The positive effects of folic acid have only been demonstrated in women. There is equivalent evidence showing a strong benefit in men – that research has not yet been conducted. The current U.S. recommended daily allowance of folic acid is 400 micrograms per day, but research studies have shown benefits only at higher doses (800 micrograms per day).
5. PotassiumInsufficient dietary potassium leads to increased blood pressure and an increased risk of stroke. This was first demonstrated in laboratory animals, and later researched in humans. Potassium likely works by changing the way that blood vessels respond to certain chemical messages in the body, helping to keep them supple and relaxed. Getting enough potassium (40 mEq/day) is important in preventing and managing high blood pressure. Because potassium can be dangerous in large amounts, be sure to notify your doctor if you start taking potassium supplements.
6. MagnesiumWhile there is some evidence to suggest that magnesium, like potassium, can have beneficial effects on blood pressure, the data is still unclear. This is largely because no negative studies on the effects of magnesium have yet been completed. In other words, while evidence has shown that diets rich in magnesium seem to lower the risk of high blood pressure, the reverse idea – that inadequate magnesium increases the risk of high blood pressure – has not yet been shown. This data is needed in order to ultimately assess the importance of magnesium and its effect on blood pressure.
7. Vitamin DVitamin D is an important nutrient that regulates many metabolic functions in the body. It helps control the level of calcium in the blood and contributes to the regulation of blood pressure. The data is unclear about what – if any – protection can be gained from vitamin D, but there is strong evidence showing that a deficiency of vitamin D can lead to high blood pressure and other cardiovascular problems. Daily supplements are usually not needed, because many foods are fortified with vitamin D.
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