They stayed alive on sweet potatoes, a rich source of calories, vitamin A and beta carotene.
People who eat carotene-rich food also have lower risk of heart disease and arthritis.
Dr. Chew said the AREDS study researchers recommend replacing the beta-carotene in supplements with lutein and zeaxanthin.
Beta carotene exists in the yellow, green and red pigmenting agents found in many fruits and vegetables.
Supplements of beta-carotene, which is a precursor of the antioxidant vitamin A, should be used with caution, however.
One proven risk reducer is a blend of high doses of vitamins C and E, beta carotene and zinc.
Beta-carotene is turned by the body into vitamin A, which is thought to be crucial in preventing serious disease.
The gene converts the compound phytoene into lycopene, which in turn is involved in the production of alpha and beta-carotene.
However, some analyses have suggested that beta-carotene, vitamin A and vitamin E supplements may shorten life rather than extend it.
The research on beta carotene supplements, however, particularly when it comes to heart disease prevention, has not shown the same benefits.
In the case of lung cancer, studies suggest that beta carotene supplementation may actually increase your risk, even if you don't smoke.
Professor Peter Bramley at the University of London, working with colleagues in Japan and Germany, has developed the tomatoes which are rich in beta-carotene.
The only disease where a beta carotene supplement may help is in the prevention or slowing of age-related macular degeneration and the associated vision loss.
Two studies found that beta-carotene supplements increased the risk of lung cancer in people who smoked more than one pack a day and drank heavily.
Initially fruit intake was boosted by half a portion a day on average - and children had slightly increased levels of beta carotene and vitamin C.
By contrast, high doses of antioxidants such as beta carotene or vitamin E slightly boosted the death rate in trials, a giant Danish study found last year.
While a 2006 French study found that people with diets high in beta-carotene had a slower decline in lung function over an eight-year period, heavy smokers and drinkers may not benefit.
Since experimental evidence has suggested that antioxidants consumed orally, such as beta carotene, can reduce signs of sun-related skin damage, the study also looked at whether a daily 30-milligram beta carotene supplement could protect against skin aging.
The researchers said that increasing the amount of beta-carotene, and other carotenoids, in foods was generally though to be more effective than taking supplements in the form of pills, as other nutrients in the food act alongside the carotenoids.
In particular, it is important to regularly consume dark green leafy vegetables including spinach, romaine lettuce, or kale which are good sources of vitamin K, E, and C, as well as beta-carotene rich, orange-colored vegetables such as carrots, sweet potatoes, and squash.
The latest part of the study, which involved about 4, 000 participants, also looked at the effect of replacing beta-carotene in the supplements formulation with lutein and zeaxanthin because of studies that found former smokers who take beta-carotene have a higher incidence of lung cancer.
Beta carotene is a type of carotenoid, a plant pigment that is a provitamin for vitamin A. During its digestion and metabolism, a percentage is converted to vitamin A, a fat-soluble vitamin that is important for vision, growth and development, and healthy immune and reproductive function.
It is a very potent antioxidant, and numerous research studies have found an association between greater intake of beta carotene-containing fruits and vegetables and a reduced risk of disease including heart disease, diabetes, osteoporosis, age-related macular degeneration (the leading cause of blindness in older Americans) and even certain types of cancers.
Many eye-vitamin formulations currently on the market are based on research conducted by the National Institutes of Health in a project called Age-Related Eye Disease Study, or AREDS. The first phase of the clinical trial, completed in 2001, found that a specific combination of vitamins C and E, along with beta-carotene and zinc, reduced the risk of age-related macular degeneration by as much as 25%.
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