Can 2 apples a day help keep the doctor away?

"Core Blimey eating two apples a day boosts health of your heart by slashing high levels of cholesterol," reports The Sun.

The story is based on a small trial that found that eating 2 apples a day for 8 weeks can slightly reduce high cholesterol levels, by up to 4%. Apples are high in fibre and polyphenols (chemicals thought to have various health benefits).

The trial included 40 healthy volunteers with slightly raised cholesterol. When they ate 2 apples a day for 8 weeks, total cholesterol and LDL ("bad") cholesterol levels reduced slightly compared with when they consumed the same number of calories from apple juice concentrate mixed with water.

It's important to note that after eating the apples their cholesterol levels were still higher than what is considered to be healthy. Eating apples should not be seen as a substitute for cholesterol-lowering drugs such as statins for people who need them.

Eating apples contributes to our recommended 5 fruit or vegetables a day. Achieving this target will help to ensure adequate vitamin and mineral intake, to reduce the risk of bowel cancer and to help maintain a healthy weight.

Where did the story come from?

The study was carried out by researchers from the University of Reading, and the Fondazione Edmund Mach in Italy. It received internal funding grant from the European Union, and a grant from AGER (Agribusiness and research) – an organisation funded by banking institutions and supporting research in the Italian food industry. The study was published in the peer-reviewed medical journal The American Journal of Clinical Nutrition.

The media in general have reported the study accurately and included expert opinion advising against trading in statins for apples.

What kind of research was this?

This was a randomised crossover trial comparing apple consumption with calorie-matched apple juice. Participants switched from fruit to juice halfway through the trial. As the same people were exposed to both interventions, this reduces the risk of patient variation affecting the results and means a smaller number of participants can be involved. However, in this case there were only 40 participants, so the results may not be representative of what would be seen in the population as a whole.

What did the research involve?

The researchers recruited 23 women and 17 men from Reading who had slightly high cholesterol. For 2 weeks before the study started, they were asked to avoid apples, apple juice and any probiotics such as live yoghurts. They were then split into 2 groups. The first was asked to consume 2 apples a day for 8 weeks. This was followed by a "washout" period of no apples for 4 weeks and then an apple substitute for 8 weeks.

The apple substitute had the same number of calories as the fresh apples but was made up of apple juice concentrate and water. The second group consumed the apple substitute for the first 8 weeks, had the 4 week washout and then ate 2 apples a day for 8 weeks. Apples are high in fibre and polyphenols (chemicals thought to have various health benefits).

What were the basic results?

After 8 weeks, the group on 2 apples a day had better cholesterol readings compared with the group on apple juice:

• total cholesterol level was lower, at 5.89mmol/L compared to 6.11mmol/L
• LDL ("bad") cholesterol was slightly lower at 3.72mmol/L compared to 3.86mmol/L
• triglyceride (another type of fat) level was also slightly improved at 1.17mmol/L versus 1.3mmol/L

Eating apples had no effect on HDL ("good") cholesterol, blood pressure or other markers of heart health.

How did the researchers interpret the results?

The researchers say their "findings show clear cause and effect between inclusion of 2 Renetta Canada apples into normal diets and improved CVD [cardiovascular disease] risk factors". They recommend that further studies look into the mechanisms behind their protective effect and work out the optimal number of apples to be consumed a day.

Conclusion

This small study has found that eating 2 apples a day may be beneficial in terms of reducing total cholesterol, LDL ("bad") cholesterol and triglyceride levels. The effect was quite small and the participants' cholesterol levels remained higher than what is considered to be healthy – i.e. less than 5mmol/L for total cholesterol and 3mmol/L or less for LDL cholesterol.

That said, any reduction is likely to be worth it in terms of reducing the risk of cardiovascular disease such as heart attack or stroke. However, eating apples should not be seen as an alternative to statins, which have been shown to have a much greater effect in lowering cholesterol.

Though the study was a randomised controlled trial, there are some limitations such as the small number of participants and the short length of the trial. It is not clear whether further reductions in cholesterol levels would occur over a longer period of time. There were some suggestions of different effects in women compared with men, but there were not enough participants to be sure.

Nevertheless, eating apples is not only likely to reduce cholesterol, but also contributes to the consumption of dietary fibre, which reduces the risk of bowel cancer. Consuming a variety of fruit and vegetables to achieve our 5 a day is likely to be better than focusing on just the 1 fruit.