Consuming high amounts of beta-carotene's less well-known antioxidant cousin, alpha-carotene, in fruits and vegetables can lower the risk of dying from all causes, including heart disease and cancer.
Both nutrients are called carotenoids - named after carrots - because of the red, yellow and orange colouring they lend to a range of produce. Once consumed, both alpha- and beta-carotene are converted by the body to vitamin A, although that process is believed to unfold more efficiently with beta-carotene than with alpha-carotene.
There are a host of yellow-orange foods such as carrots, sweet potatoes, pumpkin and winter squash, and mango and cantaloupe are rich in alpha-carotene, as are some dark-green foods such as broccoli, green beans, green peas, spinach, turnip greens, collards, Brussels sprouts, kiwi, spinach and leaf lettuce.
The researchers studied 15,318 American adults, 20 years of age or older, who took part in the Third National Health and Nutrition Examination Survey. All underwent a medical exam between 1988 and 1994, during which time blood samples were taken. Participants were tracked for a 14-year period through 2006. By that point, more than 3,800 participants had died. Most people - regardless of lifestyle habits, demographics or overall health risks - had fewer life-limiting health troubles as their blood concentrations of alpha-carotene rose. The effect was dramatic, with risks falling from 23 to 39 percent as an individual's alpha-carotene levels climbed.
Blood analyses revealed that, compared with those who had blood alpha-carotene levels of between 0 and 1 micrograms per decilitre (mcg/dL), those falling in the range of between 2 and 3 mcg/dL faced a 23 percent lower risk of death from all causes. Risk of death for those with alpha-carotene blood levels in the range of between 4 and 5 mcg/dL, between 6 and 8 mcg/dL, and 9 mcg/dL or above dropped 27 percent, 34 percent and 39 percent, respectively, versus those in the 0 to 1 mcg/dL range.
The researchers also linked higher blood alpha-carotene levels to a lower risk for dying from the two top killers: cardiovascular disease or cancer. While more research is needed, the findings generally suggest that eating more fruits and vegetables can help lower your risk for premature death.