Which is worse, a soda or a beer?

Pure, clear water: yes. Soda and other sugary drinks: no. Alcohol in its many forms: maybe, but always in moderation.

In a conversation Thursday at the Harvard Chan School, experts zeroed in on beverages, emphasizing health effects that are no less serious than the risks and benefits that come with food.

“From our first cup of coffee in the morning, to a glass of wine at night, to an energy drink, these beverages are woven into our lifestyles, our celebrations, and our cultures,” said Timothy Rebbeck, the Vincent L. Gregory Jr. Professor of Cancer Prevention and director of the Chan School’s Zhu Family Center for Global Cancer Prevention. “Yet the health impacts of the beverages, especially when it comes to cancer and the long-term effects on chronic disease and health, have been confusing and sometimes controversial.”

Alcohol, with its mixed health profile, took center stage, with Professor of Medicine and of Epidemiology Eric Rimm and Professor of Epidemiology and of Nutrition Walter Willett outlining the pros and cons. On one hand, Rimm said, moderate alcohol use has been shown to protect from heart attack and, on a population scale, lower mortality for those consuming between half a drink and a drink a day. On the other hand, studies have shown that alcohol increases the risk of several types of cancer, including breast cancer.

“What we know is that people that drink about a half a drink to a drink a day live the longest, so they die less of heart attacks,” Rimm said. “They may have a bit more cancer, but the absolute risk of heart attacks is much greater than the absolute risk of breast cancer or colon cancer.”

Willett acknowledged that the increased cancer risk can be small, especially compared with major hazards like smoking. Still, on a population scale, the increased risk of breast cancer due to drinking is large enough to counterbalance the benefits of screening, he said.

Willett and Rimm also offered practical advice to help consumers understand what the competing statistics might mean at the individual level. One has to evaluate these risks within one’s own context, they noted. For example, Willett said, a young woman with a healthy heart may want to focus squarely on alcohol’s breast cancer threat. That calculus may be different for others, depending on their specific circumstances and family background.

Though the discussion focused on the health claims surrounding moderate drinking (one drink per day for women, two for men), another panelist, Stanford’s Anna Grummon, noted that alcohol’s biggest societal impact comes from dependence and heavy drinking, conditions that lead to dangerous behaviors like drunk driving and physical violence, and can devastate families.

“What we see in the data is that many of the harms that we worry about with alcohol consumption, a lot of those are not necessarily around heart disease or cancer, but around addiction and motor vehicle crashes, and these are significant contributors to the overall death rate in the U.S.,” said Grummon, director of Stanford’s Food Policy Lab. These effects suggest that policy makers might want to “nudge” consumption downward so that more people are meeting the level of “moderate” drinking, she added.

“I don’t think any policymaker is interested in getting to zero consumption. I don’t think we want to go back to prohibition,” Grummon said, “but I think there’s interest in moving the curve a little bit to the left towards lower consumption and more people meeting the guidelines that Eric mentioned.”

The mixed picture for alcohol consumption was in contrast to what panelists agreed is a much clearer one for soda, energy drinks, and other sugar-sweetened beverages, including sugary fruit juices. A 12-ounce can of a popular soda brand has 10 teaspoons of sugar, an amount almost nobody would add to a cup of coffee or tea, Rimm said. Sugar-sweetened beverage consumption is linked to rising obesity, which itself raises cancer risk, and diabetes, which increases risk of heart attack and stroke.

“When you compare a soda to water, or soda to coffee, or soda to tea, whatever you’re comparing it to always wins,” Rimm said.

One answer for those who don’t want to give up sugar is to switch to drinks with artificial sweeteners. Willett said that sweeteners, especially aspartame, have largely proven to be safe and significantly improve a drink’s health profile. But the best choice is water, he said. And since the water supplies in most major cities are safe, a person can take it right from the tap.

Willett pointed out that the failure of the national government to act on regulating these drinks isn’t unique. Campaigns that wound up curbing smoking and banning trans fats, for example, both started at the local level, grew to the state level and then gathered enough momentum that the national government acted.

“That’s where the action is,” Willett said. “It’s state and local, even sublocal —institutional — and people can make a difference there.”