Cycling Wed: Does drinking soda cause heart attacks?

A recent trial suggesting that men who drink sugary beverages increase their heart attack risk by 20% was covered extensively in the mainstream media. There’s a lot of liquid sugar consumed around here.

I have two rules about drinking this stuff…

My criteria for indulging:

• greater than three hours on the bike,
• or after any race.

If it is over 90 degrees, I might partake in two servings. Come on folks, life is short; it seems a tad too risk averse not to treat the self once in a while. And oh how sweet those first few gulps taste after a summer criterium.

Why so stingy about a seemingly harmless beverage?

Let me tell you why I feel this way about pop. Despite what overweight people might think about thin people, this fact is true: the large majority of humans struggle to maintain a normal weight. It’s hard to be thin, and it gets harder as aging slows our metabolism. As a bike-racer with only modest gifts and limited time to train, I try to give myself every advantage possible. Basic physics dictate that lighter riders accelerate faster and overcome gravity with fewer watts.

In the quest to be as light as possible there exists a lot of low-hanging fruit. One of the easiest ways to control weight is to not drink calories. Milk, pop, beer, fruit juice and those mocha-like concoctions are all examples of insulin-spiking, fat storing, belt tightener’s. With all that good food out there to eat, it seems silly to drink calories.

That’s nutrition 101.

But now, a recent Harvard study raises the possibility that regularly drinking pop may do more than just make us jiggly and slower on the bike. Perhaps, drinking liquid sugar creates enough inflammation to raise the risk of heart attack?

The study: Sweetened Beverage Consumption, Incident Coronary Heart Disease and Biomarkers of Risk in Men

Harvard researchers studied nearly 43,000 white health professionals over 22 years. There were 3683 cardiac events during the study. The main finding: those who drank pop daily had a 20% higher risk of having a heart attack. This increased risk persisted after controlling for obvious confounders like weight, smoking and diabetes. Secondary finding: Contrary to  prior studies, consuming diet drinks did not increase the risk of heart events in this study. Inflammatory markers: Looking to explain reasons for the strong association between drinking pop and heart attack, the research team looked at levels of inflammatory markers. Not surprisingly, regular pop-drinkers had higher levels of inflammation, like C-reactive protein (CRP) and Tumor Necrosis Factor (TNF).

My take on the study:

Its three main strengths:

• First and foremost, the findings make sense. Science peeps say they are plausible. That regularly drinking caramel-colored, caffeinated boluses of sugar might increase the risk of heart disease does not seem like a stretch. It’s not as if heart disease just poofs up from nothing.
• Second, the results (in men) are consistent with the findings of the Nurses Health Study, a similarly sized study that found female pop-drinkers also sustained a higher risk of heart disease.
• Third, the findings of increased inflammatory markers in pop drinkers definitely caught my attention.

And its weaknesses:

As pointed out in an accompanying editorial, written in dense academic MPH-speak, Dr.Mark Huffman (Northwestern University) explains that association does not equal causation. It turns out there are nine criteria to assess whether we can say drinking pop causes heart attack. His editorial is highly detailed, and beyond the scope of this post, but suffice it to say, this study isn’t strong enough to go that far. The two biggest knocks against the study include the self-reporting of dietary habits and the huge possibility of confounding factors—was it the pop or something else about the pop-drinkers? These weakness are common to all such dietary association trials.

My takeaway:

I’m no nutritionist or life coach, but it seems obvious that drinking less liquid carbohydrates improves health, and perhaps even reduce the risk of heart attack.

But then there are just rewards for those monster workouts.

JMM

References: An excellent journalistic review of this study is available for free on theHeart.org.