By Dr Joe
Can alcohol cause high blood pressure? That’s the subject of this piece. I will try and explore the research and give you an insight into the problem of alcohol and high blood pressure.
The issue of alcohol use in our society is not new. People have been using and dare I say, abusing alcohol for centuries. There is no sign that this lifestyle is ever going to change despite advice form government agencies.
It does look like there’s something about alcohol that seems to attract people to it. Young adults now start young and continue with the habit for as long as possible. To imagine that doctors are now seeing alcoholic liver disease in people in their 30s is something quite puzzling.
Anyway, this piece is not about the why we drink but more about the effect of alcohol on blood pressure.
Can alcohol cause high blood pressure?
Seeing as high blood pressure is the leading single risk factor for morbidity and mortality – responsible for 10·7 million deaths and 211·8 million disability-adjusted life-years worldwide in 2015, it makes sense to take this probable causative agent seriously.
The simple answer to the question: can alcohol cause high blood pressure is; Yes, it can.
Alcohol can cause high blood pressure and the word “can” is very important in that sentence.
Because even though alcohol does cause high blood pressure, it’s not as straightforward as you might think. Like everything scientific and related to the human body, there are some other factors that come into play.
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For instance, the way women deal with alcohol is different from the way men handle alcohol. This in turn affects the outcome of drinking overall and blood pressure consequences.
The gender differences in alcohol metabolism has to do with body fat percentage, body fat distribution, body size and alcohol solubility.
This difference is illustrated in this cross-sectional analysis study of US National Health and Examination Survey data that looked at alcohol consumption in 3 groups – Non-binge drinkers, Binge drinkers of 12 times a year and Binge drinkers of more than 12 times a year.
That survey data found that the women in the binge drinking groups did not have raised blood pressure or high cholesterol but had high blood sugar instead. But the men who drank more than 5 drinks or more episodically had raised blood pressure and raised cholesterol.
Binge drinking in that study was defined as drinking 5 or more drinks per episode. They looked at men and women aged between 18 and 45 years of age who reported their alcohol use and had no cardiovascular disease.
The idea behind the study was to explore the relationship between blood pressure, blood cholesterol, blood sugar and alcohol use. But an additional outcome measure was to compare gender response to alcohol use. Their findings supports the differences in the way men and women respond to alcohol use.
I should add that the study being a cross-sectional one means the results are interpretable for that point in time only. It’s not a long term study but nevertheless shows that young adults may be exposing themselves to high blood pressure problems, if they continue to binge drink.
Effect of alcohol on blood pressure is dose-dependent
What is clear is that consistent drinking of alcohol leads to high blood pressure but as this meta-analysis suggests the effect of alcohol on blood pressure is dose-dependent.
What confuses people is the conflicting advice offered. Whereas research tells us that 16% of high blood pressure disease is due to alcohol consumption, we are also told in the same breadth that alcohol is good for our cardivascular health.
We are told and indeed there is evidence to support the view that light drinking may not do our cardiovascular system a lot of harm. In fact, light to moderate drinking is thought to reduce cardivascular complication and all-cause mortality even those with hypertension.
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The safe alcohol dose where this “magic” appears to happen according to that meta-analysis is 8 – 10 gm of alcohol per day.
This view is also supported by the previous meta-analysis. It says:
“In people who drank 2 or fewer drinks per day (12 g pure alcohol per drink), a reduction in alcohol intake was not associated with a significant reduction in blood pressure. In people who drank at least 3 drinks per day, a reduction of alcohol consumption to near abstinence was associated with a reduction in blood pressure. Reductions in systolic blood pressure and diastolic blood pressure were strongest in participants who drank 6 or more drinks per day for a 50% reduction in alcohol intake”
If heavy drinkers discontinue and abstain from alcohol, their blood pressure improves. This was shown in this study that used 24-hour ambulatory blood pressure monitoring to assess the effect of alcohol cessation over a 1 month period.
The study authors concluded:
“These results show that heavy alcohol consumption has an important effect on BP, and thus cessation of alcohol consumption must be recommended as a priority for hypertensive alcohol drinkers”
From all of the data that I looked at, it is clear to me that alcohol can cause high blood pressure. There is no doubt in my mind that, alcohol has the potential to make the control of high blood pressure harder to achieve.
This is particularly so in people who drink consistently. In people who drink every now and again i.e the social drinkers, the effect of alcohol on blood pressure is transient and inconsequential.
And the threshold for alcohol use to cause the rise in blood pressure seems to be 3 drinks or more per day.
So, what do we define as a drink?
It becomes important for us to define what a drink is. Because all the research papers refer to “a drink” and we cannot assume everyone knows what “a drink” is.
A standard drink in the United States is usually defined as 14 g of alcohol which is ethanol. Seeing as we are talking about alcohol and alcohol is present in spirits, wine and beer, how do we correlate this amount of alcohol in the different drinks on offer.
Here we go. 14 g of ethanol will be found in:
- 12 oz of beer
- 5 oz of table wine
- 1.5 oz of 80 proof (40%) distilled spirits
That guide above is not perfect. Why…because the alcohol concentration in different drinks within the same class varies. For instance, you can have 10% wine, 12% wine, 14% wine etc which confuses the picture but the guide should give you a rough idea.
How does alcohol cause high blood pressure?
The deal with alcohol and blood pressure is that there is both a direct effect and an indirect effect.
The direct effect is the fact that alcohol stimulates the sympathetic nervous system. There is a direct pressor effect on the blood vessels by alcohol.
This study gave a group of youg adults alcohol at a dose of 0.75 g/kg body weight and measured their blood pressure, heart rate and sympathetic nervous activity afterwards.
They found a raised heart rate, raised blood pressure and an increase in muscle sympathetic activity once their blood alcohol level got high.
A similar study using wine on their subjects produced similar results. The researchers found that both arousal and sympathetic activity were increased by the alcohol intake after 20 min of consuming the wine.
The way it works is this.
Initial consumption of alcohol results in what we call vasodilatation. Alcohol relaxes the blood vessels initially which means your blood pressure will be lowered. Hence, you feel flushed and warm initially when you have your drink.
Probably the reason alcohol may have some beneficial effects when consumption is at a low level.
Higher blood levels of alcohol caused by sustained intake however will reverse the relaxation of the blood vessel walls. Instead alcohol will stiffen the blood vessel walls leading to a rise in blood pressure. This is mediated by an overdrive of the sympathetic nervous system.
An additional mechanism on how alcohol causes a rise in blood pressure is that it inhibits the activity of blood vessel relaxing substances like Nitric oxide. You need your nitric oxide to have a normal low blood pressure.
Alcohol also depletes some minerals like calcium and magnesium. These minerals help to relax blood vessels just like nitric oxide. When blood vessel walls are relaxed, blood pressure is lowered. Alcohol gets in the way of that.
Indirect effect of alcohol on blood pressure
Alcohol is high in sugar and calories. Regular consumption of alcohol will lead to weight gain. Gaining excess body fat will lead to high blood pressure.
Also bear in mind, people who drink are likely to eat unhealthy diet which ultimately will lead to further weight gain. This worsens the problem of raised blood pressure in regular heavy drinkers.
Coupled with the fact that; when you are intoxicated most of the time, exercise will be the last thing on your mind. Lack of exercise will certainly have a negative impact on your blood pressure.
I should also add that alcohol intereferes with REM sleep as you saw in the video above. Not getting good REM sleep may affect your blood pressure negatively.
Below is a summary of what you need to know regarding alcohol and blood pressure:
- Low level consumption of alcohol has only a temporary effect on blood pressure
- Low level alcohol consumption may not affect blood pressure adversely long term
- Low level drinking may have beneficial effect on cardiovascular system
- The threshold for alcohol harmful effect on blood pressure is 3 or more drinks per day
- A drink is defined as 14 g of alcohol – see above for guidance
- Safe limits will be 1 drink per day for women and 2 drinks per day for men
- Sustained drinking of 3 or more drinks will cause high blood pressure in a normal person
- Having 3 or more drinks per day will make your high blood pressure worse
- High blood pressure caused by alcohol affects all races equally – white, black, hispanics, asians alike
- Cessation of alcohol will cause a reduction of high blood pressure
- Resumption of alcohol consumption after cessation will cause high blood pressure again
- Poor response to blood pressure pills may be due to alcohol intake
So, there you have it.
Alcohol does cause high blood pressure in regular drinkers of 3 or more drinks per day. That is not say if you drink less, then you should mandatorily carry on drinking.
Everyone is different. Have regular checks. You will be doing your health a favour by toning down your level of alcohol consumption, if you are having blood pressure concerns…
…even if all you have is 1 or 2 drinks per day. Use your judgement.