Healthnotes Newswire (February 28, 2008)—We all know that what we eat affects our weight, cholesterol, heart health, and so on. Now new evidence suggests that your diet may also affect your liver: A study found that cutting down on fast food and excessive calories may improve liver function.

In this study, 18 people agreed to increase their weight by 5 to 15% by eating at least two fast-food meals per day, doubling their daily calories, and adopting a sedentary lifestyle for four weeks. After one week, the majority of the people developed significantly higher levels of a liver function test called alanine aminotransferase, or ALT, compared with their previous dietary habits and with a control group of people who made no changes in their diet. The fast food group also experienced increased triglyceride levels, weight gain, and increased insulin resistance.

Fredrik Nystrom, MD, PhD, the study’s lead author and a professor at the Department of Medical and Health Sciences at the University Hospital of Linkoping in Linkoping, Sweden, believes that the change in the liver test was caused by following the high-fast-food diet and increasing calories but, more specifically, from increased carbohydrate and sugar intake.

When a person has a medical checkup, the doctor often orders blood work that measures a variety of body functions including liver function. Abnormal liver function tests are not an unusual finding in a doctor’s office and there is some evidence to suggest that the prevalence of these abnormalities is increasing. Elevated levels of certain enzymes may indicate liver injury or inflammation which, if they persist for long periods of time, can lead to cirrhosis of the liver. Common causes of elevated liver enzymes are thought to be drinking too much alcohol and using certain medications.

With this new information, Nystrom and colleagues make the point that a week of overindulgent eating and being sedentary has the capacity to affect liver function. And while alcohol consumption can create a similar picture, the elevation in lab tests may not be from alcohol but rather excessive food. “We suggest that in the clinical evaluation of [people] with elevated ALT, physicians should include not only questions about alcohol intake, but also explore whether recent excessive food intake has occurred,” they concluded.

Healthy lifetsyle tips

In fact, moderate drinking has been associated with heart health and longevity, as have the other points on this list:

• Eating generous amounts of fruits (2 servings daily), vegetables (4 servings daily), whole grains (3.4 servings daily), legumes (.5 servings weekly), and fish (2.5 servings weekly)

• Drinking moderate amounts of alcohol (2.5 drinks weekly)

• Maintaining a healthy body weight

• Exercising regularly (for best results, according to one study, 40 minutes of daily walking or biking plus one hour of additional physical activity each week—but talk to your doctor before beginning a new exercise regimen)

• Not smoking

The new study suggests that “limiting sugar and carbohydrates” may be added to these tips, though more research is needed to understand which amounts and sources pose the most risk.

(Gut doi:10.1136/gut.2007.131797)