Nutritional Characteristics of Potatoes - The Potato: Botany, Production and Uses - page 312

advocate a “consume in moderation” policy, a
minority recommends that potatoes be eaten
sparingly (Willett and Stampfer, 2003). This
change in attitudes seems to be driven in large
part by efforts to determine the cause of the
alarming surge in obesity and diabetes, with
some scientists asserting that carbohydrate con-
sumption is responsible, although this is a highly
contentious issue among nutritionists. A well-
publicized epidemiological study reported that
potatoes of all types, not just French fries and
chips, were primary contributors to weight gain
(Mozaffarian et al ., 2011). Notably, while obesity
in the USA has been increasing rapidly (CDC,
2013), potato consumption has undergone a
significant decrease, and is less than half of that
reported in at least ten other countries (Fig .
18.1 ). Moreover, the USA and Mexico are the
first and second most obese countries (OECD,
2013) yet rank 44th and 105th in potato con-
sumption in the most recent FAO data (FAO,
2009). If, indeed, potatoes are a major contribu-
tor to obesity, it is interesting to note that obesity
has not been problematic in European countries
during periods where potato consumption was
far higher than the present day. For example,
German annual potato consumption in 1900
was 628 lbs per person and over 300 lbs in the
1950s (Heinzelmann, 2008). Such statistics by
no means prove that potatoes do not contribute
to obesity, but they are interesting to note and
may suggest other factors are at play that are not
accounted for in simplistic explanations that po-
tatoes are a primary contributor.
The glycemic index is a measure of how
quickly blood sugar increases following con-
sumption of a food. Foods including potatoes,
rice, and bread typically have high glycemic
index values, which has contributed to a nega-
tive perception of potatoes. How potatoes are
prepared and what they are eaten with markedly
influences glycemic values; some cultivars give
much lower values than others (Fernandes et al .,
2005). A “modest” association between potato
consumption and the risk of type 2 diabetes has
been reported (Halton et al ., 2006), while a Jap-
anese study reported a diet rich in vegetables in-
cluding potatoes was associated with a reduced
risk (Morimoto et al ., 2012). The percentage of
the US population with diabetes soared to 8.9%
in 2011 ( Fig. 18.1c ; Center for Disease Control
(CDC)). From the 1970s until the mid-1990s,

the percentage varied by less than 1%, until be-
ginning a steep rise starting around 1995, about
the same time potato consumption started de-
creasing.
Potatoes contain bioactive compounds, and
two human feeding studies with purple potatoes
reported positive effects of potato supplementa-
tion. One study found pigmented potatoes re-
duced inflammation and DNA damage in adult
males fed 150 g of potato a day for 6 weeks (Kas-
par et al ., 2011). In another trial, subjects aver-
aging 54 years in age had a significant drop in
blood pressure without weight gain after con-
suming purple potatoes (Vinson et al ., 2012).
Twenty Canadian breeding lines were evaluated
for phenolic content, and extracts mildly in-
creased low-density lipoprotein (LDL) choles-
terol uptake in liver HepG2 cells and protected
cortical neurons against cell death. Interestingly,
the unknown bioactive components were not
dependent on potato pigmentation (Ji et al .,
2012). Extracts from purple potatoes inhibited
prostate cancer cell proliferation in a cell culture
study (Reddivari et al ., 2007b). Other cell culture
studies also reported that potatoes had inhibi-
tory effects on cancer growth (Lee et al ., 2004;
Madiwale et al ., 2012).
Unlike the complexities of interpreting epi-
demiological studies or determining the perfect
diet, assessing the nutritional content of pota-
toes is straightforward, and is the focus of the
rest of this chapter. Some foods are said to
provide “empty calories”, meaning they provide
calories but little nutritive value. Potatoes are a
nutrient-dense food; relative to the amount of
calories consumed per serving, an equal or
greater amount of the recommended daily al-
lowance for various vitamins and minerals is
provided. Figure 18.2 shows the percentage of
recommended daily values of various nutrients
in 100 g of baked potato with skin, which would
provide 87 calories, or 4% of the daily value
(data from USDA SR- 21: http://www.ars.usda.
gov/Services/docs.htm?docid=18880 ) . As seen,
this portion of potatoes provides a greater
amount of various nutrients than it does calories.
Furthermore, potatoes also provide carotenoids
and phenolics, especially pigmented potatoes.
While such compounds do not have recom-
mended daily allowances like vitamins and min-
erals, they are none the less important for health,
as discussed below. Many of the small molecules