A high-fat diet is often associated with an increased risk of heart disease, but the findings from a new study presented at the recent Experimental Biology 2011 conference in Washington, D.C, reported that a lard-rich, high-fat diet for a very short period can protect the heart from heart attacks and result in less tissue damage when heart attacks occur.
The researchers, from the University of Cincinnati, observed that short term (acute) feeding resulted in cardio-protection, whilst more chronic feeding (over six weeks) resulted in no protection – indicating that short ‘splurges’ are crucial to the impact.
“Acute high fat feeding elicits a cardio-protective effect and preserves cardiac function in a mouse model,” explained the authors, led by Lauren Haar from the department of systems biology and physiology at the University of Cincinnati.
“However, cardio-protection was not observed after more chronic feeding (6 weeks), indicating that this effect is independent of any potential chronic effects of high fat feeding (serum cholesterol range, obesity, diabetes etc),” added the authors.
High fat risk?
Approximately one million Americans suffer a heart attack each year, 400,000 of which are fatal. A leading cause of such heart attacks atherosclerosis, a process in which cholesterol builds up in the arteries, blocking blood flow to the heart.
Although long term high-fat diets are clearly associated with increased risk of heart disease, the authors noted that clinical evidence also suggests that people with high cholesterol levels may have better survival rates following heart attacks than those with lower levels. However the mechanism for such a phenomenon is unclear.
The new tested this study tested the idea that short term (acute) high fat feeding sets off a systematic signalling cascade that offers cardio-protection and improves in vivo myocardial function following heart attack.
The researchers established test groups comprised of seven male mice. Haar said that female mice were not included in order to eliminate the effects of estrogen and metabolism of fat.
Each group was fed a lard-based high-fat diet, with 60 percent of the calories coming from saturated fat, for 24 hours, one-, two-, or six weeks. At the same time a group received a standard grain and vegetable-based diet.
After the feeding periods the researchers induced ischemic injury in the hearts of the mice, similar to what humans experience during a heart attack.
The researchers found that the injury to the heart tissue among the mice that received the high-fat for shorter ‘splurges’ (24 hours, one- and two-weeks) was reduced by 70 percent compared to the group fed a high-fat diet for six weeks.
Chronic (six week) high fat feeding was shown to result in larger injury to the heart, as were control fed animals.
In addition the researchers found that mice fed a high-fat diet for 24 hours, then returned to a control diet for 24 hours prior to heart attack experienced a prolonged or ‘late phase’ protection against injury. They said this indicates that short-term high fat feeding in animal models could preserve cardiac function.
Haar explained that the new study adds to an existing body of research which has found that certain people with high cholesterol levels have better survival rates after heart injury or heart failure than patients with lower cholesterol levels. However, the reason for this phenomenon remains unclear.
However, the results of the current study have led the team to investigate why the cardiac protection goes away over time, in more detail by considering whether a genetic component might be involved.
“We hope that additional studies, which are now underway, will lead us to understand why the cardio-protective effect occurs and why it goes away over time … This understanding will provide us with better insights into the interaction between diet, health and heart diseases,” explained Haar.
Presented at Experimental Biology 2011 (April 9-13)
“Acute high fat feeding influences cardiac function and confers cardioprotection against ischemic injury”
Authors: L. Haar, X. Ren, Y. Liu, M. Jiang, S. Koch, M. Tranter, J. Rubinstein, W.K. Jones