Medical researchers have given us numerous reasons to cut back on our intake of added sugars and alcoholic drinks.
Now, here’s another: Zachary T. Schug, a researcher at the Wistar Institute, has been delving into how added sugars and alcohol can fuel the growth and spread of cancerous tumors.
To support that research, the National Institutes of Health gave Schug, assistant professor in Wistar’s Molecular & Cellular Oncogenesis Program, its prestigious New Innovator Award in 2019. It comes with a five-year grant of nearly $2.7 million.
The links between sugar, alcohol and cancer are receiving so much attention that the U.S. Department of Agriculture and the Department of Health and Human Services recently released new dietary guidelines, recommending no more than one alcoholic drink a day for men and women — it had previously been two drinks a day for men. It also recommended that no more than 10% of a person’s total daily caloric intake be from added sugars.
Schug recently talked with us about his research.
How did you become interested in studying alcohol and high-fructose foods and their link to cancer?
It started during my postdoctoral fellowship at the Beatson Institute for Cancer Research in Glasgow, Scotland. During that time, I became really interested in cancer metabolism — how cancer cells feed themselves.
It’s generally accepted among cancer researchers that glucose, a sugar, and glutamine, an amino acid, are the two major nutrient sources for cancer cells. But when those nutrients are in short supply or unavailable — for a number of reasons — the tumor must find alternative nutrient sources in order to survive and grow.
We began looking into those alternative nutrients, and that’s when we stumbled upon acetate. We found that many types of cancer use acetate as an alternative nutrient source.
Acetate is probably better known as acetic acid. It’s what gives vinegar its smell and taste. But consuming vinegar isn’t the problem. The acetate in our bodies almost exclusively comes from the natural bacteria that live in our gut, what we call our microbiome.
How does that work?
One of the primary foods that our bacteria make into acetate is the sugar fructose, and particularly high fructose corn syrup, which is an additive in a lot of foods. It makes its way into the gut, where the bacteria turn it into acetate, and that gets delivered to the rest of the body.
The other major source of acetate is alcohol. We’ve been really interested in this for a number of years. When we drink alcohol, we can get high blood alcohol levels. Our livers try to sober us up. They do that by converting all that alcohol into acetate.
Having just a single drink can cause your blood acetate level to double. Multiple drinks can cause blood acetate levels to rise to 20 times higher than normal. Chronic alcoholics always have high blood alcohol and would therefore always have high blood acetate levels, too. And if you think about people that combine sugars and alcohol — rum and coke, for example — it creates what we think is a perfect storm for the progression of cancers, with very high amounts of acetate being made from the high fructose corn syrup in the coke and alcohol in the rum.
At the moment, we do not think that high amounts of acetate actually cause cancer. It’s more that if there is a cancer forming in the body, it may be using acetate as a nutrient source. That is what we have been researching, and what we received funding for.
What are you finding out?
We set out to see if eliminating the ability of a cancer cell to use acetate can prevent tumor growth. Sure enough, we found that when we engineer cancer cells so that they cannot use acetate as a nutrient source, or if we treat them with a drug that blocks the ability of the cancer cell to use acetate, we can significantly decrease tumor growth and sometimes even achieve full tumor regression in our mouse models.
My lab and the Wistar Institute are now interested in developing acetate inhibitors with the hope to one day enter clinical trials with humans. The interesting part about targeting acetate is that it seems to be a universal nutrient source for nearly all cancer types, from breast, to prostate, to liver, to brain.
At the end of the day, we’re seeing how diets change blood acetate levels and how this impacts tumor metabolism. Our initial studies are showing that this could be a powerful way of limiting tumor growth.
We think diet can improve the treatments that we already have. We’re already seeing in the mouse models that if we take certain nutrients out of their diet, and we then combine that with the standard-of-care therapies — chemotherapy, radiation, immunotherapy — we’re getting much better effects, much longer remission rates. There is a lot of interest in how we can exploit customized diets to improve patient outcome because this would be at little to no cost to patients or the health-care system.
I still do not think we have a firm grasp on how our bodies break down and redistribute the foods we eat. A lot of it has to do with the inability to control diet in humans. So studying diet and how it changes us is a challenge. But with advanced technologies we are now beginning to better understand how what we eat affects not only our normal healthy tissues, but also different diseases, such as cancer.
What is your reaction to the USDA and HHS dietary guidelines?
I was pleased to see the focus on eating a variety of nutrient-dense foods. And on limiting the amount of food. I think overeating is a major issue. We’re eating too much and we’re not exercising enough. We all know it. But we don’t do it.
The other thing they talked about was limiting calories from added sugars and fat — things like the high fructose corn syrup we discussed earlier. Fortunately, the report showed that there is a trend toward more Americans abiding by this recommendation, which is great. I don’t think eliminating them is necessary. Having a can of soda once in a while is fine. But think of these added sugars as treats, and treat them as such.
The recommendation to limit alcohol to one drink a day is a step in the right direction. The dangers of alcohol are generally downplayed, and it’s so prevalent in our society. Every occasion has alcohol. Decreasing drinking is something society needs to get a better handle on.
Have you altered your own diet because of your research?
Most definitely. First and foremost, my food mantra is “anything in moderation.” For me, I’ll eat everything from a salad to a really fatty steak. Greens, pulses and grains, nuts and seeds, fresh vegetables and lots of fruit are always good. One thing I try to incorporate, probably more than most Americans, is fish. I thank Scotland for that. When I was there, I had access to phenomenal seafood. I used to eat fresh fish and shellfish all the time. Now, in my household, we eat fish at least once a week.
The last thing I have done is drastically reduce my alcohol consumption. When I was in Scotland, I did enjoy a Scotch now and then. But now I have an alcoholic drink only at celebrations or social gatherings and even then, only a single drink.