Vitamins in Fleshy Fruits - Fruit Ripening: Physiology, Signalling and Genomics - page 128

discovery. This led to the identifi cation of
13 organic micronutrients that are required
in the human diet and which are therefore
classifi ed as vitamins (Fitzpatrick et al. ,
2012). They comprise fat-soluble vitamins
(vitamins A, D, E and K) and water-soluble
vitamins (vitamin B complex: B1, B2, B3,
B5, B6, B8, B9 and B12 and vitamin C). A
wealth of studies has also underscored the
prominent role played by micronutrients,
including vitamins, in promoting human
health. This led to the establishment of
recommendations for minimum intake per
day, the recommended daily allowance
(RDA), for each vitamin in order to avoid
vitamin defi ciency (Table 8.1). The RDA
may vary according to the needs of the
individuals, which may depend on their
age and physiological stage: for most
vitamins, the requirements are not the
same for children and adults or for
lactating females and adult males. The
RDA for several vitamins is regularly
updated according to advances in food and
nutrition research. As an example, the RDA
for vitamin C was recently revised (in
2000) in the USA from the previous recom-
mendation of 60 to 120 mg day -1 for breast-
feeding women. The prevention of vitamin
defi ciency diseases, among others, led to
the recent establishment of dietary
guidelines by various national govern-
ments and by the FAO/WHO (2004). These
guidelines recommend eating fi ve or more
servings of fruits and vegetables a day,
including two to four servings of fruit (a
fruit serving is equal to one piece of apple
or a half cup of sliced fruit, for example).
Whilst these objectives can easily be
reached in western countries, in which a
variety of fruits and vegetables are
available for diversifying the staple diet,
the intake of food with high micronutrient
density is more problematic for popu-
lations subsisting mostly on grain- or tuber-
based diets. As an alternative, food can be
biofortifi ed with vitamins. However, it has
been shown, for example for vitamin C,
that supplements are less effi cient than
vitamins taken from plant products (Inoue

et al. , 2008), probably because of the
synergistic effect between vitamins and
other phytonutrients.
Due to the wide diversity of fl eshy fruit
species, the broad climatic conditions in
which they can grow and the large
variability in their micronutrient com-
position, a large panel of fl eshy fruits can
provide appreciable levels of vitamins in
many parts of the world (Table 8.1). As an
example, the recommended fi ve servings of
fruits and vegetables may provide >200 mg
of vitamin C, which is the RDA proposed
by some authors for preventing cancer
(Levine et al. , 1996). Fruits such as mango,
avocado and guava can be major sources of
vitamin A, vitamins E and K, and vitamin
C, respectively. In addition, fruits less rich
in vitamins but available all year round in
many countries, like tomato, may cover a
signifi cant part of the recommended intake
for several vitamins. For a given species,
wide variations in vitamin content are
usually found by screening cultivated
germplasm or related species, thus pro-
viding potential targets for improving fruit
vitamin content by genetic means. As well
as the widespread cultivated fl eshy fruit
species shown in Table 8.1, biochemical
screening has revealed the high micro-
nutrient density of other fl eshy fruit
species found in the wild and/or cultivated
locally (e.g. Amazonian fruits; Rodriguez-
Amaya, 1999; Justi et al. , 2000). These
fruits can become important sources of
vitamins locally or can be exploited for
their nutritional value, as is the case for the
Amazonian fruits acerola ( Malpighia
glabra ) and camu-camu ( Myrceria dubia ),
which are rich in vitamin C (Justi et al. ,
2000; Badejo et al. , 2009). Additional
factors affecting fruit nutritional value that
need to be considered are which part of the
fruit is edible (for example, vitamin C
accumulates mostly in the peel in many
fruit species), preharvest environmental
conditions and cultural practices (for
example, increasing light intensity will
increase both provitamin A and vitamin C
content, whilst high nitrogen may reduce