The study was presented at the American Heart Association's Scientific Sessions 2007 in Orlando, Florida this week and was carried out by Dr Benjamin D Horne, director of cardiovascular and genetic epidemiology at Intermountain Medical Center and adjunct assistant professor of biomedical informatics at the University of Utah in Salt Lake City, and his colleagues.
Horne said that:
"People who fast seem to receive a heart-protective benefit, and this appeared to also hold true in non-LDS people who fast as part of a health-conscious lifestyle."
For 30 years scientists have known that LDS members or Mormons in Utah were less likely to die of heart disease than other Americans, including non LDS residents in Utah. They had put this down to the fact it is against their religion to smoke, but also wondered if it might be due to other religious practices.
Horne and colleagues looked at the angiography records of patients who took part in the Intermountain Heart Collaborative Study between 1994 and 2002. Angiography is a type of X-ray exam that helps specialists see if there are any blockages in the heart's blood vessels.
They found 4,629 male and female patients of average age 64 whose angiography results clearly showed either that they had coronary artery disease (CAD) or that they did not. To be classed as clearly having CAD, at least 70 per cent narrowing had to be found in at least one artery. Patients whose coronary arteries showed less than 10 per cent blockage or narrowing were classed as clearly not having CAD.
The patients whose records showed their religion to be LDS had less CAD than those whose records showed another or no religion. The results showed that 61 per cent of LDS patients had CAD compared with 66 per cent of non-LDS patients.
Horne said that even after taking into account smoking status, or when they looked just at the non-smokers, they still found a lower rate of CAD in the LDS members:
"We thought this was very interesting, so we devised a survey about other behaviors associated with LDS that might bring a health benefit," explained Horne.
In the second part of the study, Horne and colleagues found that fasting was the "strongest predictor of lower heart disease risk", and the patients who fasted also had less coronary disease, said Horne.
In the second part of the study, the researchers surveyed 515 patients (also of average age 64) who underwent coronary angiography between 2004 and 2006 and asked them not only about their religious preference but more specifically about: smoking habits, fasting (skipping two consecutive meals, including drink), abstaining from tea, coffee and alcohol, taking a day of rest once a week, going to church, and giving time, money and goods to charity. These practices are all observed by LDS members, but the questions were asked of all patients.
The results of this second investigation showed that:
- Patients who fasted were significantly less likely to have a CAD diagnosis than those who did not (59 per cent of the fasting patients had arterial blockage of 70 per cent or more compared with 67 per cent of the non-fasting patients).
- People who fasted were 39 per cent less likely to be diagnosed with CAD.
- Patients who did not drink tea were less likely to have a CAD diagnosis.
- However, once fasting was factored in, the link between tea drinking and lower CAD became insignificant.
- The impact of fasting was most strongly apparent when those patients with CAD were compared with those with minimal or no CAD (less than 10 per cent arterial blockage).
- In this comparison, the odds of having a CAD diagnosis was 45 per cent lower among fasting patients.
"When you abstain from food for 24 hours or so, it reduces the constant exposure of the body to foods and glucose."
"One of the major problems in the development of the metabolic syndrome and the pathway to diabetes is that the insulin-producing beta cells become desensitized. Routine fasting may allow them to resensitize - to reset to a baseline level so they work better."
He was quick to point out the study was not suggesting diabetics should skip meals.
The researchers called for more studies based on a wider range of populations throughout the US.
The American Heart Association said those who are interested in these findings should note this was not a randomized or controlled trial, and there could be other factors that link fasting with reduced CAD not found by this study.
Click here for American Heart Association Scientific Sessions 2007.