Login | November 02, 2026
Caffeine, just how does it affect the body?
Published: November 2, 2026
The American Heart Association (AHA) has promoted the cardiovascular health benefits of moderate coffee consumption for the past several years…that is of course if the total amount of caffeine ingested is in the 400 milligrams or less per day range (roughly three to five cups) without sugars, sweeteners, flavors or added fillers.
And this advocacy is based on research linking coffee consumption to health benefits such as lowering the risks of heart disease, stroke, heart failure, and Type 2 diabetes.
But don’t get too giddy, because there’s other areas where caffeine consumption isn’t considered so beneficial - like for instance when your consumption is well beyond their recommendations.
In this case research has determined that higher doses, such as from energy drinks and energy shots, can produce elevated blood pressure and irregular heart rhythms.
All of this information - and more - can be found in a new scientific statement published in the American Heart Association's peer-reviewed journal “Circulation.”
The statement, titled ”Caffeine and Cardiovascular Disease.” was published on July 21, 2026, and it declares that, “Moderate caffeine or coffee consumption (up to 400 mg/d caffeine or ≈3–5 cups of coffee at 8 oz per cup) is safe for most adults and is associated with lower risk of cardiovascular disease, including coronary heart disease, stroke, heart failure, and AF, as well as hypertension and type 2 diabetes. Indeed, large prospective cohort studies with long-term follow-up consistently demonstrate modest inverse associations between habitual coffee consumption and all-cause mortality across diverse populations.”
While on the over-consumption side research indicates, “Higher caffeine intake, such as levels found in energy drinks including energy shots, was associated with cardiovascular harm, such as increased risk of high blood pressure and irregular heart rhythm. Energy drink shots may contain 40-69 mg of caffeine per fluid ounce, 3-4 times more caffeine than regular caffeinated coffee.”
So here’s a brief abstract that highlights some of the areas this recent AHA statement has addressed concerning caffeine’s effects on the body.
Metabolization
Our livers metabolize the caffeine, and it generally reaches its highest concentration in our bodies within an hour, but factors like genetics, metabolism, age and past caffeine use can play big roles in how each of us metabolizes this drug.
Blood Pressure
Now what’s interesting here concerning coffee consumption is that researchers have found an Inverse J-shaped relation (where a variable initially decreases slightly or stays flat, and then accelerates sharply upward like the letter J) between natural caffeinated products and blood pressure, meaning that 1-3 cups/day may link to a slight initial/temporary increase or risk of rising BP over time for people with optimal baseline readings whereas consumption above 3-4 cups shows a flatter or lower/neutral risk pattern in observational data - though individual responses vary.
This is how they came to the determination that 3-5 cups is generally safe for most adults and neutral/beneficial for broader cardiovascular risks (stroke, heart failure)
Diabetes
Research on the effects of caffeine consumption on Type 2 diabetes suggests that it might reduce insulin sensitivity in the short term and that it could possibly lower the risk of developing Type 2 diabetes.
Cholesterol
Both good and bad news here because research has shown that cafestol, a compound in caffeinated and decaffeinated coffees, is associated with higher levels of low-density lipoprotein (bad cholesterol), which is not so good because it’s present in espresso, French press, Turkish and boiled coffees.
The good news is that cafestol is not present in coffee brewed with paper filters and in instant coffee.
Heart Rhythm
Caffeine’s effect on heart rhythm indicates that drinking 1-3 cups of caffeinated coffee/day was not associated with an increased risk of a-fib or abnormal heart rhythms.
Yet those same levels of caffeine consumption may be associated with premature ventricular contractions (PVCs), and really high doses of caffeine (like in energy drinks and energy shots) have been linked to abnormal heart rhythms - even in low cardiovascular disease risk groups like healthy adults younger than 30.
Heart Disease & Stroke
Consuming 2-4 cups of caffeinated coffee/day was linked to a lower risk of heart disease, heart failure and stroke, whereas consuming more than 4 cups of caffeinated coffee/day may increase the risk of heart failure.
If you want to take a deeper dive into this AHA statement paper go to https://www.ahajournals.org/doi/10.1161/CIR.0000000000001454