In small quantities, alcohol may have beneficial relaxation effects on the circulation, but above a certain intake, alcohol increases the risk of developing high blood pressure and affects how well your blood pressure is controlled.
Alcohol and high blood pressure
In small doses, alcohol has a relaxing effect on the circulation and acts as a diuretic to increase fluid and salt losses through the kidneys. This can lower blood pressure and the beneficial effects of a moderate intake of alcohol is enhanced by antioxidants found in both red and white wine.
As a result, drinking one or two glasses (100ml each, or 10g alcohol) of wine is generally deemed acceptable if you have well-controlled high blood pressure.
However, a higher alcohol consumption (3 or more drinks per day) leads to sodium retention, and has adverse effects on the liver. This leads to the production of substances that promote inflammation, insulin resistance and causes blood pressure to rise. In the long-term, alcohol can damage the liver and lead to fibrosis and cirrhosis.
Alcohol and blood pressure readings
Above an intake of 3 drinks (30g alcohol) per day, every additional drink (10g alcohol) will increase your average systolic blood pressure (upper reading) by 1-2 mmHg, and your diastolic blood pressure (lower reading) by 1 mmHg.
Binge drinking more than 4 units of alcohol in one session can lead to dangerous spikes in blood pressure or trigger an abnormal heart rhythm.
A high alcohol intake is most harmful when it occurs without food, and women are more susceptible to these adverse effects than men.
Women tolerate alcohol less well than men
Women tolerate alcohol less well than men for a variety of reasons, including:
- Differences in body size and weight – a petite female can tolerate less alcohol than a tall, muscular male.
- Women have lower concentrations of a stomach enzyme, gastric alcohol dehydrogenase, which breaks down ethanol, so that less is deactivated in the stomach and more is absorbed into the circulation for transport to the liver. Women absorb an estimated one-third more alcohol than a man of the same size when they consume equal amounts.
- Within the body, alcohol is distributed across body fluids. Water makes up between 55% and 65% of male body weight, but only 45% to 55% of female body weight. As a result, there is less fluid in which to distribute absorbed alcohol and it is less diluted in women.
- Significantly higher blood alcohol concentrations are obtained in older females compared with younger females. This effect cannot be fully explained by differences in body water volume between young, middle-age and older females. This effect may be result from an age-related decline in the ability to process alcohol.
- Women using hormonal methods of contraception may be at greater risk for toxic effects of alcohol. The oral contraceptive Pill seems to interact with enzymes such as aldehyde dehydrogenase so that higher levels of acetaldehyde (linked with hangover and other toxic effects) build up.
- Women are more vulnerable to developing alcoholic liver disease and higher alcohol-related blood pressure than men. This may be because the response of certain pathways involved in fatty acid metabolism are less efficient in females than in males, so that fats are more likely to accumulate in liver cells (fatty liver disease).
Alcohol and blood pressure
If you have high blood pressure and drink more than 1 or 2 glasses of wine per day, on average, aim to cut back.
Every drink you cut back by, on a daily basis, can reduce both your systolic and diastolic blood pressure by around 1 mmHg. This could be the difference between avoiding high blood pressure medication or having to take a higher dose or an additional antihypertensive drug.
Usual advice is that both men and women drink no more than 14 units of alcohol per week on a regular basis.
One unit (10g alcohol) is equivalent to: 300ml (½ pint) beer OR 100ml wine Or 50ml sherry OR 25 ml spirits.
To reduce your alcohol intake:
- Keep putting your glass down to reduce the amount you sip by habit
- Savour each sip, holding it longer in your mouth
- Alternate alcoholic and non-alcoholic drinks
- Choose unsweetened fruit juices, coconut water or non-alcoholic cocktails (eg mango juice with coconut water)
- Drink sparkling mineral water or soda water with a dash of lime juice
- Try tonic water with a dash of Angostura bitters instead of a gin and tonic
- Mix chilled wine with sparkling mineral water for a refreshing spritzer
- Elderflower cordial diluted with mineral water makes a great substitute for white wine.
You can download a free Drinkaware app to record your drinks to help you track and moderate your alcohol intake.
Kudzu (Japanese arrowroot) extracts may help to reduce alcohol cravings. Research suggests this action is due to the presence of two isoflavones (daidzein and daidzin).
If your blood pressure is borderline or raised, self-monitoring is key to maintaining good control.
Click here for advice on choosing a blood pressure monitor to use at home.
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