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Recently there have been studies with conflicting results about the health benefits or harms from coffee consumption. Overall, it seems like moderate intake is OK and beneficial for adults, but too much may cause harm. And avoid caffeinated coffee if pregnant. Yesterday I posted about several recent studies finding health benefits from daily coffee consumption.

Coffee has anti-inflammatory effects, and contains more than a thousand chemical compounds. Over the years many studies found health benefits with regular and decaffeinated coffee, especially when a filter is used in the brewing process (e.g. drip coffee). But when the coffee is made by methods that don't filter the coffee (e.g. French press) the results may show harm, especially if large quantities are consumed daily.

The following are two recent studies finding that coffee consumption is associated with health benefits, and two studies finding potential harm from coffee consumption of over 6 cups a day. Note that whether the coffee is filtered or not may make a difference in results (the last 2 studies).

From (Jan. 11, 2021) Science Daily: Higher coffee intake may be linked to lower prostate cancer risk ...continue reading "Coffee Can Have Health Benefits, But Perhaps Harmful In Large Amounts"

Evidence is building that caffeine should be avoided during pregnancy because it harms the developing baby. A recent study found when caffeine (coffee!) is consumed during pregnancy, then structural changes occur in the brain of the developing baby. These changes can be seen years later in brain scans, and these appear to result in behavioral changes in the children. The minimal, but noticeable behavioral changes were behavioral issues, attention difficulties, and hyperactivity.

The Univ. of Rochester School of Medicine and Dentistry researchers  found subtle changes in brain pathways ("alteration of the microstructure of critical fiber tracts") between brain regions that could be seen in the children at age 9 to 10 years. They analyzed brain scans (from MRIs) of 9157 children, of which 4,135 had mothers that reported consuming caffeine more than once a week.

Other studies find that health problems associated with caffeine (coffee) intake during pregnancy are miscarriage, stillbirth, low birth weight and/or small for gestational age, and childhood leukemia. There is a dose-response effect - the more caffeine is ingested, the more negative health effects.

Other human studies looking at this issue are observational, but negative health effects are supported by animal research going back more than four decades. Caffeine crosses the placenta and goes to the baby. Negative health effects occur because the fetus can not clear the caffeine well because it lacks an enzyme that metabolizes caffeine.

Unfortunately, medical guidelines in both the US and Europe are that moderate (up to 200 mg) ingestion of caffeine during pregnancy is OK, which means about 2 cups of regular coffee a day. Since studies show it's not OK, it's time to revise the guidelines!

From Science Daily: Brain changed by caffeine in utero

New research finds caffeine consumed during pregnancy can change important brain pathways that could lead to behavioral problems later in life. Researchers in the Del Monte Institute for Neuroscience at the University of Rochester Medical Center (URMC) analyzed thousands of brain scans of nine and ten-year-olds, and revealed changes in the brain structure in children who were exposed to caffeine in utero.  ...continue reading "Avoid Caffeine During Pregnancy"

Good news for coffee lovers! Drinking 1 or more cups of coffee a day was associated with a reduced risk of heart failure in three large heart disease studies. However, drinking decaffeinated coffee was not.

Researchers analyzed results of the 3 studies, in which more than 21,000 adults were followed at least 10 years. The studies did not differentiate between type of coffee consumed and how it was prepared (drip, espresso, percolated, French press). The researchers point out that other studies have similar findings - that increased consumption of coffee is associated with decreased heart disease deaths or deaths from any cause.

Many studies also find other benefits from daily coffee consumption, such as lowered risk of diabetes, some cancers, and some neurological conditions. However, avoid caffeine when trying to conceive and during pregnancy - then it is associated with harm to the pregnancy and fetus (e.g. with miscarriage, stillbirth, low birth weight and/or small for gestational age).

Excerpts from Science Daily: Coffee lovers, rejoice! Drinking more coffee associated with decreased heart failure risk

Dietary information from three large, well-known heart disease studies suggests drinking one or more cups of caffeinated coffee may reduce heart failure risk, according to research published today in Circulation: Heart Failure, an American Heart Association journal.  ...continue reading "Drinking Coffee Associated With Lower Heart Failure Risk"

Pregnant women receive all sorts of advice on what to do or not do during pregnancy. For years medical guidelines in both the US and Europe have been that moderate (up to 200 mg) ingestion of caffeine during pregnancy is OK, which means about 2 cups of regular coffee a day.

However, a recent review of studies by Reykjavik University Professor Jack E. James found that ingesting caffeine during pregnancy is linked to health problems and that there is no safe level during pregnancy. In other words,  caffeine and caffeinated beverages should be avoided during pregnancy and when trying to conceive.

Health problems associated with caffeine intake during pregnancy are miscarriage, stillbirth, low birth weight and/or small for gestational age, childhood leukemia, and childhood overweight and obesity. Studies typically found a dose-response effect - the more caffeine is ingested, the more negative health effects.

Human studies looking at this issue are observational, but negative health effects are supported by animal research going back more than four decades. Caffeine crosses the placenta and goes to the baby. Negative health effects occur because the fetus can not clear the caffeine well because it lacks an enzyme that metabolizes caffeine.

Professor James points out that the industry established and funded the group ILSI (International Life Sciences Institute) which successfully fought any FDA warnings about caffeine and pregnancy, and which attacked any research suggesting it could be harmful to pregnancy or the fetus. [Why am I not surprised about the success of the industry group? And that they published their own "research" showing caffeine was benign in response to scientific research showing negative health effects.]

Excerpts from Science Daily: No safe level of caffeine consumption for pregnant women and would-be mothers

Women who are pregnant or trying to conceive should be advised to avoid caffeine because the evidence suggests that maternal caffeine consumption is associated with negative pregnancy outcomes and that there is no safe level of consumption, finds an analysis of observational studies published in BMJ Evidence Based Medicine.   ...continue reading "Avoid Consuming Caffeine During Pregnancy"

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More good news for coffee lovers. A study that looked at a large sample of adults in the US found that there is a dose-response association for daily coffee consumption and body fat (adiposity). Higher coffee intake (both regular and decaf) was associated with lower body fat in women, but not men.

The biggest effects were seen in women aged 20 to 44 years (who drank 2 to 3 cups/day), and in 45 to 69 year old women who drank 4 or more cups of coffee per day - that is, they had lower total body fat and trunk body fat when compared to those who didn't drink coffee.

Coffee has over 1000 bioactive compounds in it, such as caffeine, chlorogenic acids, and diterpenes. Recent studies found that moderate coffee intake (3 to 4 cups/day) lowers the risk of type 2 diabetes, heart disease, (early) death, lower risk of some cancers, and has a beneficial effect on metabolism (increases it) and inflammation. [Note: chronic inflammation is linked to a number of diseases, so want to lower it.]

The researchers suggest that there are compounds in coffee (other than caffeine) that regulate weight and act as "antiobesity compounds". Perhaps view drinking coffee as a healthy diet strategy for women!

Excerpts from Science Daily: Coffee linked to lower body fat in women

Women who drink two or three cups of coffee a day have been found to have lower total body and abdominal fat than those who drink less, according to a new study published in The Journal of Nutrition ...continue reading "Drinking Coffee Associated With Lower Body Fat in Women"

The Scandinavians really love to drink coffee, and of course researchers study the health effects of all that coffee drinking. Two recent studies both found health benefits from drinking filtered coffee (such as drip coffee), but not unfiltered coffee.

A study conducted in Norway found that over a 20 year period drinking filtered coffee daily was associated with lower death rates, when compared to those who did not drink coffee or drank unfiltered coffee. The best health effects (lowest mortality rate) were associated with drinking 1 to 4 cups per day of filtered coffee, and the unhealthiest (highest mortality rate) was drinking 9 or more cups per day of unfiltered coffee.

The researchers thought that unfiltered coffee raised the cholesterol levels, because of the lipid-raising components of coffee - the diterpenes kahweol and cafestol, which are filtered out by coffee filters. This could explain the association between unfiltered coffee and higher death rates from heart disease. Other studies have found that higher consumption of filtered coffee results in lower levels of markers of inflammation.

As was discussed in an earlier post, a recent study from Sweden found that drinking 2 to 3 cups of drip coffee (using a filter) daily lowers the risk of type 2 diabetes, while drinking boiled coffee has no health effect. The researchers put it nicely, that habitually drinking filtered coffee has a "protective role" on type 2 diabetes development.

On the other hand, other popular ways of preparing coffee don't use filters - French press, espresso, percolator, and coffee pods, and so may have similar not-so-great health effects to boiled coffee. But still unknown at this time - studies are needed.

From Science Daily: How to make the healthiest coffee

Today scientists announce the healthiest way to make a brew ...continue reading "Drinking Filtered Coffee Is Healthier Than Unfiltered Coffee"

Drinking drip coffee is healthier than boiled coffee? A study conducted in Sweden suggests that drinking 2 to 3 cups of drip coffee (using a filter) daily lowers the risk of type 2 diabetes, while drinking boiled coffee has no health effect.

The 60% lower rate of type 2 diabetes in drip coffee drinkers (as compared to boiled coffee drinkers) could be due to coffee filters capturing diterpenes - a molecule that is linked to health problems. But the filters still allow beneficial molecules, such as phenolic substances, to pass into the coffee. In other words, preparing the coffee 2 different ways results in coffee with different chemical compositions and properties.

The researchers were able to separate out the 2 types of coffee drinkers simply by analyzing the metabolites in the blood - there were differences in the metabolites (substances made when the body breaks down coffee) of boiled coffee vs drip coffee drinkers.

As a daily coffee drinker, who only uses a drip coffee maker, I am pleased with the results. [Many studies find health benefits from coffee consumption.] But as the researchers note, we need to also look at coffee prepared other popular ways, all of which don't use filters, and so are (maybe) similar to boiled coffee: French press, espresso, percolator, and coffee pods. Will they also have the same effect as drinking boiled coffee?

From Science Daily: Filtered coffee helps prevent type 2 diabetes, show biomarkers in blood samples  ...continue reading "Drip Coffee, But Not Boiled Coffee, Lowers The Risk Of Type 2 Diabetes"

Pregnant women have been advised to keep their consumption of coffee and other caffeinated beverages (tea, sodas, cocoa, energy drinks), and chocolate containing foods to a minimum for decades. Currently the American College of Obstetrics recommends that women consume less than 200 mg of caffeine (from any source) per day during pregnancy. This is less than 2 cups of regular coffee  or 4 cups of regular black tea. But a recent  study's findings suggest that the levels should be kept much lower.

The study of 941 mother/baby pairs in Ireland found that each 100 mg increase of caffeine per day was associated with a lower birth weight, shorter length of pregnancy (gestational age), shorter birth length of the baby, and smaller head circumference of the baby at birth. The strongest associations between those who consumed the most caffeine (when compared to those who consumed the least) was with lower birth weight.

The researchers think this occurs because caffeine crosses the placenta easily, but during pregnancy there is a slowed metabolism of caffeine (so it takes longer to get it out of the body). Similar results have been found in other recent studies. [On the other hand, for not pregnant women - coffee and tea are linked to all sorts of health benefits - here, here.]

From Medical Xpress: Caffeinated beverages during pregnancy linked to lower birth weight babies

...continue reading "Keep Caffeine To A Minimum During Pregnancy"

Two more studies find that drinking coffee is associated with health benefits, which is good news for coffee drinkers. The first study found an association of daily coffee drinking (both caffeinated and decaffeinated) and lower risk of premature mortality (early death) among half a million United Kingdom residents - as compared to those who don't drink coffee. Studies finding an association with daily coffee consumption and health benefits (e.g. lower risk of type 2 diabetes, some cancers, and death from heart disease and stroke) are really adding up. The studies generally find the positive health effects to be dose dependent, usually up to about 4 cups of coffee.

The second study found that in mice, an amount of caffeine equivalent to four cups of coffee was beneficial to mitochondria, improved mitochondria-dependent processes, and protected heart cells from damage. The researchers thought that the same process occurs in humans. What are mitochondria?Mitochondria are the “powerhouses of the cell”. Mitochondria are organelles found in the cells of every complex organism. They produce about 90% of the chemical energy that cells need to survive.

From Medical Xpress: Fresh grounds for coffee: Study shows it may boost longevity

Go ahead and have that cup of coffee, maybe even several more. New research shows it may boost chances for a longer life, even for those who down at least eight cups daily. In a study of nearly half-a-million British adults, coffee drinkers had a slightly lower risk of death over 10 years than abstainers ...continue reading "More Good News About Coffee"

Great news coffee drinkers! Another study - this time a large analysis of over 200 studies found that coffee consumption is linked to many health benefits. The best results were from drinking 3 to 4 cups of coffee daily (as compared to none), with a reduction in "all cause" mortality (death from any cause), and cardiovascular disease and death.

They also found a lower risk of cancer in general, and with a lower risk of several specific cancers (endometrial, prostate, melanoma, non-melanoma skin cancer, liver cancer) and neurological (Parkinson's disease, Alzheimer's disease, and depression), metabolic (including type 2 diabetes, metabolic syndrome), and liver conditions.

However, during pregnancy high coffee consumption (as compared to low or no consumption) was associated with low birth weight, preterm birth in the first and second trimester, and pregnancy loss. The researchers also found an association between coffee drinking and a small risk of fracture in women, but not in men. Decaffeinated coffee seemed to have many of the same benefits as caffeinated coffee - especially at 2 to 4 cups a day.

[UPDATE: A 2020 review of studies found that ingesting caffeine during pregnancy is linked to health problems and that there is no safe level during pregnancy. In other words,  caffeine and caffeinated beverages should be avoided during pregnancy and when trying to conceive.]

Excerpts from Science Daily:

Three to four cups of coffee a day linked to longer life

Drinking coffee is "more likely to benefit health than to harm it" for a range of health outcomes, say researchers in The BMJ today. They bring together evidence from over 200 studies and find that drinking three to four cups of coffee a day is associated with a lower risk of death and getting heart disease compared with drinking no coffee. Coffee drinking is also associated with lower risk of some cancers, diabetes, liver disease and dementia. However, they say drinking coffee in pregnancy may be associated with harms, and may be linked to a very small increased risk of fracture in women.

The included studies used mainly observational data, providing lower quality evidence, so no firm conclusions can be drawn about cause and effect, but their findings back up other recent reviews and studies of coffee intake. As such, they say, excluding pregnancy and women at risk of fracture, "coffee drinking appears safe within usual patterns of consumption" and they suggest that coffee could be safely tested in randomised trials.

To better understand the effects of coffee consumption on health, a team led by Dr Robin Poole, Specialist Registrar in Public Health at the University of Southampton, with collaborators from the University of Edinburgh, carried out an umbrella review of 201 studies that had aggregated data from observational research and 17 studies that had aggregated data from clinical trials across all countries and all settings. (Original study.)