Grapefruit - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 359

Pectin
Pectin is a soluble fiber that has been proved in animal
studies to slow down the progression of atherosclerosis.
In one study, animals fed with a high-cholesterol diet
plus grapefruit pectin had 24% narrowing of their arteries
compared to animals fed high-cholesterol diet but without
grapefruit pectin, which had 45% narrowing (Cerda et al.,
1994). Researchers found that both red and blond grapefruit
types are capable of reducing blood levels of low-density
lipoprotein or LDL (“bad”) cholesterol, while the red grape-
fruit is known to also lower triglycerides. On the basis of
these benefits, the researchers concluded that adding fresh
red grapefruit to the diet could be beneficial for persons
with high cholesterol, especially those who also have high
triglycerides.

(Hakim et al., 2000). MCP significantly decreased tumor
metastasis to the lung by more than 90% in mice (Platt and
Raz, 1992; Spreen and Enten, 2009).
Grapefruit juice was found to contain compounds which
protect the human body against lung and colon cancer. Re-
searchers concluded that drinking three glasses of grape-
fruit juice a day reduced the activity of an enzyme that ac-
tivates cancer-causing chemicals found in tobacco smoke,
whereas in rats whose colons were injected with carcino-
gens, grapefruit and its isolated bioactive compounds (api-
genin, hesperidin, limonin, narrigin, narigenin, nobiletin)
increased the suicide (apoptosis) of cancer cells and also
increased the production of normal colon cells (Turner et al.,
2004). Researchers also confirmed that grapefruit may help
to prevent weight gain by lowering insulin levels.
Frequent drinking of grapefruit juice was found to re-
duce formation of calcium oxalate kidney stones. This was
demonstrated through a study where women were given
500-1,000 ml of grapefruit, apple, or orange juice daily
and found that their urinary pH value and citric acid excre-
tion increased, significantly dropping their risk of forming
calcium oxalate stones (Honow et al., 2003).
Grapefruit juice significantly increases the production
and activity of liver detoxification enzymes responsible for
preparing toxic compounds for elimination from the body
(Hahn-Obercyger et al., 2005). The liver clears out tox-
ins, including carcinogens, using a two-step process called
Phase I and Phase II detoxification. Grapefruit works in
both phases to enhance the liver's ability to remove cancer-
causing toxins (Hahn-Obercyger et al., 2005).
It was reported by Rouseff et al. (1987) and Lu et al.
(2006) that cultivars of citrus juice from the United States
and China are richest in flavonone glycosides (naringin,
hesperidin and neohesperidin). Rouseff et al. (1987) re-
ported 720 mg/liter of neohesperdin in C. paradisi ('K-
Early' tangelo). The flavonoids narigin and hesperidin are
found mainly in the peel (albedo, membrane, and pith)
of citrus fruits (Lu et al., 2006). Hot water or treatment
with base can remove these. These flavonoids are reported
to have therapeutic benefits in treating capillary diseases
(blood vessel fragility and permeability complaints) and
also function as anticarcinogens. Naringenin is found con-
centrated in grapefruit and helps to repair damaged DNA
in human prostate cancer cells (cell line LNCaP). It helps
restore damaged DNA by inducing two enzymes that re-
pair DNA during the replication stage. These enzymes,
8-oxoguanine-DNA glycosylase and DNA polymerase
beta, are both involved in the DNA base excision repair
pathway (Gao et al., 2006). Unlike other cancers, prostate

Health benefits
Grapefruit is among the alkaline foods recommended to use
in potentially eliminating cancer. Other fruits include avo-
cados, lemons, and limes (Crowell, 1999). Recent findings
show that a substance called modified citrus pectin (MCP),
citrus peel compound (d-limonene), provides powerful can-
cer protection (Spreen and Enten, 2009). It is commonly
used as a gelling agent for canning foods and making jel-
lies. Pectin that has not been modified cannot be absorbed
by the digestive system, whereas modified pectin can be
absorbed right into the bloodstream (Crowell, 1999). MCP
is on the FDA's list of ingredients that are generally rec-
ognized as safe and is available in capsules or a powder
(Spreen and Enten, 2009).
For cancer cells to spread, or metastasize, they must first
clump together, and galectins on their surface are thought
to be responsible for much of this clumping potential. Re-
search shows that MCP is particularly rich in galactose,
which binds to the surface of cancer cells, and as a result,
MCP can block cancer cells from grouping together and
spreading (UNCTAD, 2009).
A 2007 study examined the clinical benefits of MCP in
patients with advanced solid tumors (LEF, 2010). An earlier
study examined MCP's effectiveness against prostate can-
cer metastasis in rats and found that while the oral MCP did
not affect primary tumor growth, it significantly reduced
metastases when compared to control animals (Vigushin
et al., 1998). A human study examined the effect of MCP
on prostate specific antigen (PSA) doubling time in seven
prostate cancer patients (PSA is an enzymatic tumor marker
and its doubling time tends to reflect the speed at which the
cancer is growing). They found that four of seven patients
exhibited more than 30% lengthening of PSA doubling time