If you or a loved one is scheduled for surgery anytime soon, beware. There’s a risk for heart attack and stroke during many types of surgery. This risk is generally small during noncardiovascular operations (less than 1%), but during cardiovascular operations, it can be as high as 10%!

What can you do about it? Surprisingly, according to a new study, the risk may be lowered significantly by simply changing your diet in the week before surgery.


Prior studies on mice and other animals had shown that overall calorie restriction can help the body resist stress, including the stress of surgery, but researchers at the Harvard School of Public Health in Boston wanted to see whether cutting back on certain nutrients—not just overall calories—was the real key. So they gave mice different types of diets to find out. Past research on fruit flies had showed that reducing protein, specifically, from the diet extended their lifespan better than restricting carbohydrates, so researchers made sure that one of the diets eliminated protein.

In the first part of the study, for 14 days, mice ate one of three diets—either an “unlimited” traditional diet (mice could eat as much as they wanted of protein, fat and carbohydrates)…a “limited” traditional diet made of the same nutrients but in a restricted amount…or an unlimited protein-free diet. Then, to mimic the experience of a heart attack or stroke mid-surgery, researchers blocked blood flow to the kidneys of the mice for 35 to 45 minutes and then abruptly restarted the blood flow. Next, they examined the mice to see how each fared after the “surgery.”

The protein-free group…

  • Had a strikingly better survival rate. In the week following surgery, 100% of the protein-free group survived…25% of the unlimited traditional group survived…and none of the limited traditional group survived.
  • Had about 70% less waste in their blood than both traditional groups, which indicated that their kidneys were functioning better.
  • Had a better appetite and did not lose any weight after surgery, whereas surviving mice from the unlimited traditional group lost about 6% of their weight.

So eliminating protein before the “surgery” was a big help!

In the second part of the study, the researchers wondered if the mice could get the same protection in less time. The great news is that it came very close—six days of a protein-free diet before surgery was nearly as effective as one that was two weeks long.


So what is it about eliminating protein that helped the mice? Coauthor James Mitchell, PhD, assistant professor of genetics and complex diseases at Harvard School of Public Health, explained that when mice (and humans) don’t consume the essential amino acids that protein contains, their bodies go on an alert that prepares them to resist stress—including the stress of surgery. “We can’t say for sure whether removing protein from a human’s diet before surgery will provide the same results, but we’re hopeful.”

There are, of course, some downsides to not eating any protein. For example, protein deficiency can lead to side effects that may include feeling tired and weak, losing muscle, losing hair, recovering more slowly from injury, gaining weight and potentially experiencing a spike in blood sugar (if you replace protein with carbs). But it’s unknown yet if those side effects would be evident and/or severe after just one week of going protein-free. Plus, those problems are reversible once a person starts eating protein again.

Dr. Mitchell isn’t ready to recommend any particular presurgery dietary restrictions for humans. But, personally, based on these results, if I have to go under the knife, I’m going to talk to my doctor about steering clear of protein in the one week before the operation.