Food and diet

Spice for mice

“Research shows that the curry spice turmeric can help prevent heart failure and repair damaged hearts”, the Daily Mail reported today.

The newspaper says that the researchers behind this study on mice hope that the findings could apply to humans too.

The spice turmeric contains a substance called curcumin, which has long been used in Asian medicine and is linked to health benefits. Heart failure, where the heart loses its ability to pump blood around the body, is caused by the damage caused by heart attack or disease.

This animal study found that curcumin reduced heart enlargement and scarring in laboratory mice. The authors of the study are quoted as suggesting that the spice may have healed the damaged hearts by switching off the genes that cause the heart to become enlarged and scarred. They also warn that eating curry may not be the answer as many dishes are high in fat and that “the benefits are not strengthened by eating more curcumin”.

Whether these findings apply to humans is not investigated in this study, and until human trials take place, it would be advisable to consider turmeric as an ingredient that adds flavour and colour to food rather than one with any health benefits.

Where did the story come from?

Hong-Liang Li, from the Division of Cardiology at the University of Toronto, and colleagues from other organisations in Canada, the US and the UK carried out the research. The study was supported in part by grants from the Heart and Stroke Foundation of Ontario. The study was published in the peer-reviewed medical journal: The Journal of Clinical Investigation .

What kind of scientific study was this?

In this experimental, laboratory study the researchers tested the effect that the chemical curcumin, responsible for the yellow colour of the spice turmeric, has on cultured rat heart cells and on the hearts of live mice.

The researchers aimed to test the theory that curcumin reduces heart enlargement and scarring by affecting a  process called 'histone acetylation'. This is a process that changes the structure of the protein part of chromosomes (linear threads of DNA and protein which transmit genetic information and are contained within all cell nuclei).

The research article reported on eight parts to this complex study, three of which used live mice. Each part of the study built on the results of the previous part. The study started by exposing newborn rat heart muscle cells to a chemical that can cause heart enlargement. After 48 hours' culture, cells which had been treated with curcumin showed a reduction in the usual protein synthesis and an increase in cell size that would usually be expected.

The researchers then carried out the same test in live mice and performed several experiments that looked at the acetylation of histones, a possible way in which the spice was having its effect.

Finally they divided 24 live mice into two groups; a group which was fed the spice three times a day and a group which received a placebo. All the mice had a band fitted around the aorta, the main artery from the heart; this provided an imitation model of heart failure by putting added strain on the heart. Various aspects of heart function were then measured (such as blood pressure and heart muscle thickness) to test if the spice could reduce these indicators of heart failure.

What were the results of the study?

The researchers report that curcumin reduced heart enlargement and scarring in mice. They also report that they identified biochemical changes which support their idea that curcumin has an effect on histone acetylation and signalling pathways that rely on histone acetylation.

What interpretations did the researchers draw from these results?

The researchers conclude that the study shows, for the first time, that curcumin protects against the overgrowth of heart muscle cells in laboratory studies and in live mice. They suggest that curcumin protected the mice hearts from cardiac hypertrophy, inflammation and fibrosis by interrupting the biological pathways that change proteins, the binding of DNA and the pathways that signal these activities.

They go on to say that these findings support the idea that curcumin could protect against cardiac hypertrophy and heart failure.

What does the NHS Knowledge Service make of this study?

This appears to be a well-conducted study investigating the effects of a common food ingredient in mice. However, several major issues remain unresolved, particularly the question of whether the findings apply to humans. Also unknown are the the ideal dose for the chemical, how it works, and whether it will have any harmful effects.

Despite the authors’ suggestion that the spice may have preventive and therapeutic benefits in humans, it would seem wise to wait for human studies before taking action.

Sir Muir Gray adds...

If you enjoy spicy foods keep up the intake; but if you have heart disease it is better to rely on walking more, stopping smoking, and taking the treatment prescribed.

NHS Attribution