Despite the interest in raw foods diets, little research has been
conducted about them. A small German study examined blood levels of
carotenoids in 198 strict raw foods diet followers. Carotenoids are
found in fruits and vegetables and include substances associated with a
lower risk of diseases like cancer, such as beta-carotene,
alpha-carotene, and lycopene. Study subjects ate close to 95 percent by
weight of their foods as raw foods and had followed this diet for at
least two years.
Because of their high fruit and vegetable intake, people eating a
raw foods diet would be expected to have high levels of these
carotenoids in their blood. Most study subjects, especially those eating
more than 3 1/2 pounds of fruits and vegetables per day, had blood
beta-carotene levels in the normal range. Surprisingly, however, blood
lycopene levels were below the reference values in more than
three-quarters of study subjects. This may be because the lycopene from
raw foods was not well-absorbed. Cooking foods like tomatoes, which are
a good source of lycopene, has been shown to increase lycopene
absorption. Other factors that may have affected carotenoid absorption
were the amount of fat in the subjects’ diets and whether the high
fat foods were eaten at the same meal as foods high in carotenoids.
Dietary fat provided an average of 30 percent of calories; the main
dietary sources of fat were nuts, seeds, and avocados. Dietary fats have
been shown to increase the amount of carotenoids that are absorbed in a
meal. Those subjects who ate the lowest amount of fat and oil also had
the lowest blood levels of carotenoids. For those eating a raw foods
diet to increase carotenoid absorption, especially absorption of the
carotenoid lycopene, fat intake may need to be increased. Additionally,
fat sources should be at the same meal as good sources of lycopene.
Garcia AL, Koebnick C, Dagnelie PC, et al. 2008. Long-term strict
raw food diet is associated with favourable plasma beta-carotene and low
plasma lycopene concentrations in Germans. Br J Nutr 99:1293-1300.
By Reed Mangels, PhD, RD, FADA