Who Should Avoid Coffee?

Oct 19 Coffee copy.jpeg

Do coffee drinkers live longer than non-coffee drinkers? Is it "wake up and smell the coffee" or don't wake up at all? I discuss these questions in my video, Coffee and Mortality.

The largest study ever conducted on diet and health put that question to the test, examining the association between coffee drinking and subsequent mortality among hundreds of thousands of older men and women in the United States. Coffee drinkers won, though the effect was modest, a 10-15% lower risk of death for those drinking six or more cups a day. This was due specifically to lower risk of dying from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.

However, another study that amount of coffee was found to increase the death rate of younger people under age 55. It may be appropriate, then, to recommend that you avoid drinking more than four cups a day. But if you review all the studies, the bottom line is that coffee consumption is associated with no change or a small reduction in mortality starting around one or two cups a day, for both men and women. The risk of dying was 3% lower for each cup of coffee consumed daily, which provides reassurance for the concern that coffee drinking might adversely affect health, or at least longevity.

A recent population study found no link between coffee consumption and symptoms of GERD, reflux diseases such as heartburn and regurgitation. If you actually stick a tube down people's throats and measure pH, though, coffee induces significant acid reflux, whereas tea does not. Is this just because tea has less caffeine? No. If you reduce the caffeine content of the coffee down to that of tea, coffee still causes significantly more acid reflux. Decaf causes even less, so GERD patients might want to choose decaffeinated coffee or, even better, opt for tea.

Coffee intake is also associated with urinary incontinence, so a decrease in caffeine intake should be discussed with patients who have the condition. About two cups of coffee a day worth of caffeine may worsen urinary leakage.

A 2014 meta-analysis suggested that daily coffee consumption was associated with a slightly increased risk of bone fractures in women, but a decreased risk of fractures in men. However, no significant association was found between coffee consumption and the risk of hip fracture specifically. Tea consumption may actually protect against hip fracture, though it appears to have no apparent relationship with fracture risk in general.

Certain populations, in particular, may want to stay away from caffeine, including those with glaucoma or a family history of glaucoma, individuals with epilepsy, and, not surprisingly, people who have trouble sleeping. Even a single cup at night can cause a significant deterioration in sleep quality.

We used to think caffeine might increase the risk of an irregular heart rhythm called atrial fibrillation, but that was based on anecdotal case reports like one of a young woman who suffered atrial fibrillation after "chocolate intake abuse." These cases invariably involved the acute ingestion of very large quantities of caffeine. As a result, the notion that caffeine ingestion may trigger abnormal heart rhythms had become "common knowledge," and this assumption led to changes in medical practice.

We now have evidence that caffeine does not increase the risk of atrial fibrillation. Low-dose caffeine--defined as less than about five cups of coffee a day--may even have a protective effect. Tea consumption also appears to lower cardiovascular disease risk, especially when it comes to stroke. But given the proliferation of energy drinks that contain massive quantities of caffeine, one might temper any message that suggests that caffeine is beneficial. Indeed, 12 highly caffeinated energy drinks within a few hours could be lethal.


To learn more about various health aspects of coffee, see my videos Coffee and Cancer, What About the Caffeine?, Preventing Liver Cancer with Coffee?, and Coffee and Artery Function.

What else can we consume to live longer? Check out Nuts May Help Prevent Death, Increased Lifespan from Beans, Fruits and Longevity: How Many Minutes per Mouthful?, and Finger on the Pulse of Longevity.

And, for more on controlling acid reflux, see Diet and GERD Acid Reflux Heartburn and Diet and Hiatal Hernia.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Original Link

Who Should Avoid Coffee?

Oct 19 Coffee copy.jpeg

Do coffee drinkers live longer than non-coffee drinkers? Is it "wake up and smell the coffee" or don't wake up at all? I discuss these questions in my video, Coffee and Mortality.

The largest study ever conducted on diet and health put that question to the test, examining the association between coffee drinking and subsequent mortality among hundreds of thousands of older men and women in the United States. Coffee drinkers won, though the effect was modest, a 10-15% lower risk of death for those drinking six or more cups a day. This was due specifically to lower risk of dying from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.

However, another study that amount of coffee was found to increase the death rate of younger people under age 55. It may be appropriate, then, to recommend that you avoid drinking more than four cups a day. But if you review all the studies, the bottom line is that coffee consumption is associated with no change or a small reduction in mortality starting around one or two cups a day, for both men and women. The risk of dying was 3% lower for each cup of coffee consumed daily, which provides reassurance for the concern that coffee drinking might adversely affect health, or at least longevity.

A recent population study found no link between coffee consumption and symptoms of GERD, reflux diseases such as heartburn and regurgitation. If you actually stick a tube down people's throats and measure pH, though, coffee induces significant acid reflux, whereas tea does not. Is this just because tea has less caffeine? No. If you reduce the caffeine content of the coffee down to that of tea, coffee still causes significantly more acid reflux. Decaf causes even less, so GERD patients might want to choose decaffeinated coffee or, even better, opt for tea.

Coffee intake is also associated with urinary incontinence, so a decrease in caffeine intake should be discussed with patients who have the condition. About two cups of coffee a day worth of caffeine may worsen urinary leakage.

A 2014 meta-analysis suggested that daily coffee consumption was associated with a slightly increased risk of bone fractures in women, but a decreased risk of fractures in men. However, no significant association was found between coffee consumption and the risk of hip fracture specifically. Tea consumption may actually protect against hip fracture, though it appears to have no apparent relationship with fracture risk in general.

Certain populations, in particular, may want to stay away from caffeine, including those with glaucoma or a family history of glaucoma, individuals with epilepsy, and, not surprisingly, people who have trouble sleeping. Even a single cup at night can cause a significant deterioration in sleep quality.

We used to think caffeine might increase the risk of an irregular heart rhythm called atrial fibrillation, but that was based on anecdotal case reports like one of a young woman who suffered atrial fibrillation after "chocolate intake abuse." These cases invariably involved the acute ingestion of very large quantities of caffeine. As a result, the notion that caffeine ingestion may trigger abnormal heart rhythms had become "common knowledge," and this assumption led to changes in medical practice.

We now have evidence that caffeine does not increase the risk of atrial fibrillation. Low-dose caffeine--defined as less than about five cups of coffee a day--may even have a protective effect. Tea consumption also appears to lower cardiovascular disease risk, especially when it comes to stroke. But given the proliferation of energy drinks that contain massive quantities of caffeine, one might temper any message that suggests that caffeine is beneficial. Indeed, 12 highly caffeinated energy drinks within a few hours could be lethal.


To learn more about various health aspects of coffee, see my videos Coffee and Cancer, What About the Caffeine?, Preventing Liver Cancer with Coffee?, and Coffee and Artery Function.

What else can we consume to live longer? Check out Nuts May Help Prevent Death, Increased Lifespan from Beans, Fruits and Longevity: How Many Minutes per Mouthful?, and Finger on the Pulse of Longevity.

And, for more on controlling acid reflux, see Diet and GERD Acid Reflux Heartburn and Diet and Hiatal Hernia.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Original Link

Avoid Carnitine and Lethicin Supplements

 

 

 

 

 

 

 

 

Avoid Carnitine and Lethicin Supplements

A landmark study in the New England Journal of Medicine shows that choline in eggs, poultry, dairy and fish produces the same toxic TMAO as carnitine in red meat, which may help explain plant-based protection from heart disease.

Earlier this year, a research team at the Cleveland Clinic offered another explanation as to why meat intake may be related to mortality (see, for example, Harvard’s Meat and Mortality Studies). They noted that “Numerous studies have suggested a decrease in atherosclerotic disease risk  [our  number 1 killer] in vegan and vegetarian individuals compared to omnivores,” but reduced intake of dietary cholesterol and saturated fat may not be the full story.  The researchers found that within 24 hours of carnitine consumption—eating a sirloin steak, taking a carnitine supplement—certain gut bacteria metabolize the carnitine to a toxic substance called trimethylamine, which then gets oxidized in our liver to TMAO, trimethylamine-n-oxide, which then circulates throughout our bloodstream. There’s a diagram in my 9-min video Carnitine, Choline, Cancer and Cholesterol: The TMAO Connection.

The way we know it’s the gut bacteria is that if you give people antibiotics to wipe out their friendly flora, you can apparently eat all the steak you want without making any TMAO, but then if you wait a couple weeks until your gut bacteria grows back, you’re back to the same problem.

What’s so bad about this TMAO stuff? It appears to increase the buildup of cholesterol in the inflammatory cells in the atherosclerotic plaques in our arteries, increasing our risk of heart attack, stroke, and death. The role of these inflammatory “foam” cells (so-called because they’re so packed with cholesterol they look foamy under a microscope) is explained in my video series that starts with Arterial Acne and Blocking the First Step of Heart Disease.

What does carnitine do? It’s involved in energy production in the mitochondria (“power plants”) in our cells. The enzyme that uses carnitine to help us burn fat, carnitine palmitoyl transferase, is actually upregulated by about 60 percent in those eating meat-free diets, which may help explain why those eating plant-based diets tend to be slimmer. More details in my video How to Upregulate Metabolism.

How do we keep carnitine away from our gut bacteria? Well there’s zero dietary requirement; our body normally makes all that we need. The problem is that the bodies of other animals also make all that they need so when we eat them, their carnitine can end up in our gut for those bacteria to feast upon, resulting in TMAO.

Some animals make more carnitine than others. Carnitine is concentrated in red meat, and so this new body of research has led to recommendations to decrease red meat consumption as well as avoid carnitine-containing supplements and energy drinks.

What most media reports missed, though, is that gut bacteria can turn the choline found in eggs, poultry, fish, dairy, and lecithin supplements into TMAO too. So it’s not just a problem with red meat. The good news is that this may mean a new approach to prevent or treat heart disease: “The most obvious is to limit dietary choline intake.” But if that just means decreasing egg, meat and dairy consumption, the “new” approach sounds just like the old approach.

Unlike carnitine, we do need to take in some choline, so should vegans be worried about the modest amounts of choline they’re getting from beans, veggies, grains, and fruit? And same question with carnitine. There’s a small amount of carnitine found in fruits, veggies, and grains as well. Of course it’s not the carnitine itself we’re worried about, but the toxic TMAO, and you can feed a vegan a steak without getting a TMAO spike. Literally. The researchers convinced a long-time vegan to eat an 8-ounce sirloin, in the name of science. The vegan got the whopping carnitine load, but hardly any TMAO was produced. Apparently, the vegans don’t develop those TMAO-producing bacteria in their gut, and why would they?

It’s like the whole prebiotic story I detail in videos like Boosting Good Bacteria in the Colon Without Probiotics. When we eat a lot of fiber, we select for fiber-munching bacteria, and some of the compounds they make with fiber are beneficial, like the propionate that appears to have an anti-obesity effect I explored in Fawning Over Flora. It seems that if we eat a lot of animal products we may instead be selecting for animal-munching bacteria, and some of those waste products—like the trimethylamine—may be harmful.

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image credit: avlxyz / Flickr

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