Fruits’ fiber for life

The Mediterranean Diet is considered a pattern of eating with nine components: vegetables, legumes, fruits and nuts, cereals (whole grains), fish, olive oil, dairy products, meats, and alcohol. Last week we discussed a study that suggests that it's the overall pattern - not one specific component - that contributes to reduced cellular aging. Nevertheless, research continues into the effects of the specific components in an effort to understand how those individual nine points contribute to the diet as a whole.

In Spain, an ongoing study known as PREDIMED (Prevención con Dieta Mediterránea) (in English: Prevention with the Mediterranean Diet) yields today's insights into the role of fiber in the Mediterranean Diet (Am J Clin Nutr 2014;100:1498-1507).

Between 2003 and 2009, the PREDIMED study authors recruited over 8,000 total participants: men between the ages of 55 and 80 and women 60 to 80 who were at increased risk of cardiovascular disease. They had no active heart disease at the start of the study, but they either had type 2 diabetes or had at least 3 risk factors for heart disease (these include things like smoking, high blood pressure, poor cholesterol scores, overweight or obesity, or family history of heart disease). The participants responded to detailed dietary questionnaires on a yearly basis and also provided blood samples for lab testing.

For this analysis, the researchers analyzed the dietary and health records of over 7,200 of the PREDIMED participants over a period of 5.9 years (on average). They compared the dietary fiber intakes of those who died during the study period with those who did not. They also broke down the analysis by the cause of death as well as the sources of fiber, including vegetables, fruits, and whole grains.

Those participants with the most fiber of all types in their diet were 37% less likely to die from any cause than those with the least fiber in their diet. More interesting, however, is that the separate analyses of the different sources of fiber showed that while more fiber from fruit meant a lower risk of death, the same was not true of fiber from vegetables or from whole grains. Intrigued, the researchers compared low-glycemic-index fruits (such as cherries or grapefruit) with high-glycemic-index fruits (such as cantaloupe, watermelon, or pineapple), with no significant difference seen between the two types.

The researchers note that the Spanish population ate mostly white bread, so their intake of whole grains was fairly low, while their vegetable intake at the start of the study was already very high. This might affect the tendency for fruit intake to be the significant factor in their risk of death. That said, those individuals who increased their intake of fruit over the course of the study did have a reduced risk of death when compared to those whose intake of fruit remained low throughout, which suggests that it is indeed the fruit that was the significant factor.

What this means for you

Fruit is great for you for more reasons than just the fiber: they're a good source of many vitamins, including antioxidants, and make great snacks. Make fruit a larger part of your life with our tips on how to eat more fruit.

First posted: December 17, 2014