A plant-based diet that includes
plenty of fresh fruits, vegetables and nuts is known to reduce the risk for
oxidative stress-related chronic diseases such as cancer and heart disease. It
is difficult to understand the role of diet in chronic diseases since more than
25,000 bioactive food constituents are known to modify the processes related to
these diseases. Bioactive food constituents derived from plant-based foods are
called phytochemicals. These phytochemicals protect the cells from damage
caused by free radicals, hence they are known as antioxidants. Benefits of
antioxidants also include health effects such as longevity, cell
maintenance and DNA repair.
So, with the objective of
developing a comprehensive food database for antioxidants, Monica Carlsen from
the University of Oslo, Norway, and her colleagues, procured 3139 food samples
globally and analyzed them for their total antioxidant content.
The researchers found that 'there
are several thousand-fold differences in antioxidant content of foods'. 'We
find that plant-based foods are generally higher in antioxidant content than
animal-based and mixed food products', say authors. They found that fruits,
nuts, chocolate and berries are 5 to 33 times higher in antioxidant content
than meat products. The results showed that berries, fruits, nuts, chocolate,
vegetables and their products had high antioxidant values.
Coffee is also high in antioxidants but the amount depended
on the type of coffee. For example, double espresso was found to be richest in
antioxidants at 16.33 mmol / 100g and single Caffe Latte was lowest at 0.89
mmol / 100g. However, antioxidants from coffee beans varied from 12.30 to 22.73
Red wine (1.78 to 3.66 mmol/100 g
antioxidant content), pomegranate juice and prepared green tea with
antioxidants at 0.57 to 2.62 mmol/100 g, as well as grape juice, prune juice
and black tea (0.75 to 1.21 mmol/100 g) are beverages rich in antioxidants; while
beers and soft drinks had the least antioxidant content.
Water does not contain
'Interestingly, the antioxidant
content in human breast milk is comparable to that in pomegranate juice,
strawberries and coffee and on average higher than the antioxidant content
observed in the commercially available infant formulas analyzed in our study'
noted the authors.
Most of the spices and herbs are
excellent sources of antioxidants. The dried herbs and some dried fruits are
potentially richer in antioxidants since the drying process leaves most of the
antioxidants intact in the dried end product.
Among the herbal and traditional
plant medicines, the sap from the tree trunk of the species Croton lechler, used in South America for wound healing
and as an antifungal, antiseptic, antiviral and anti-hemorrhagic medicine, has very high antioxidant content.
Triphala (capsule), an Ayurvedic
herbal formulation, having anti-inflammatory, antibacterial, wound healing, and
anti-cancer properties, is an
excellent source of antioxidants at 706.25 mmol / 100g.
Arjuna, another Auyrvedic formula
(146.95 mmol/ 100g), Amla (301.14 mmol /100g), and Goshuyu-tou, a traditional
Chinese kampo medicine (132.58 mmol/ 100g), have health beneficial activities
because of high antioxidant values.
Berries and their products with
their high content of phytochemicals such as flavonoids, phenolic acids, etc
are also antioxidant-rich. Dried amla (Indian gooseberry) is the richest in
antioxidants with 261.5 mmol/100 g, while some berry jams are poorest in
antioxidants at 0.5 mmol /100g. Bilberries, black currants, blackberries, goji
berries, sea buckthorn and cranberries also have high antioxidant values.
Breakfast cereals, grains and
grain products, and beans and lentils do not have much antioxidant to boast
about with buckwheat whole meal flour being highest at 2.0 mmol /100g.
Dairy products, cakes and dessert
are low in antioxidant content, in the range of 0.0 to 0.8 mmol /100g.
Similarly, 'eggs are almost devoid of antioxidants with the highest antioxidant
values found in egg yolk (0.16 mmol/100 g)', found the researchers. And so are
meat, fish, poultry and their products. But some prepared chicken and beef
products have antioxidant values between 0.5 and 1.0 mmol /100 g.
On the other hand, antioxidant
content in chocolate ranged from 0.23 in white chocolate to 14.98 mmol /100g in
dark chocolate. Antioxidant contents increased with increasing cocoa content in
Most nuts are also important
source of antioxidants. The researchers found that antioxidant content
increased in nuts with pellicle (the thin skin) compared to nuts without
pellicle. Walnut with pellicle has the highest (33.3 mmol/100 g) antioxidant
According to the researchers,
'the variation in the antioxidant values of otherwise comparable products is
large' because of reasons such as growing conditions, seasonal changes, storage
differences in manufacturing procedures and processing. Again, antioxidant-rich
food does not mean that they are good sources of antioxidants or that all
antioxidants provided in the diet are bioactive. 'Bioavailability differs
greatly from one phytochemical to another, so the most antioxidant rich foods
in our diet are not necessarily those leading to the highest concentrations of
active metabolites in target tissues. Thus a food low in antioxidant content
may have beneficial health effects due to other food components or
phytochemicals executing bioactivity through other mechanisms', they say.
They concluded - 'The ultimate
goal of this research is to combine these strategies in order to understand the
role of dietary phytochemical antioxidants in the prevention of cancer,
cardiovascular diseases, diabetes and other chronic diseases related to
Reference: Carlsen, M. H., et al. The total antioxidant content
of more than 3100 foods, beverages, spices, herbs and supplements used
worldwide. Nutrition Journal 2010, 9:3