HerbalEGram: Volume 14, Issue 1, January 2017 |
Editor’s Note: Each
month, HerbalEGram highlights a conventional food and briefly explores its
history, traditional uses, nutritional profile, and modern medicinal research.
We also feature a nutritious recipe for an easy-to-prepare dish with each
article to encourage readers to experience the extensive benefits of these
whole foods. With this series, we hope our readers will gain a new appreciation
for the foods they see at the supermarket and frequently include in their
diets.
The basic materials for this series were compiled
by dietetic interns from Texas State University in San Marcos and the
University of Texas at Austin through the American Botanical Council’s (ABC’s)
Dietetic Internship Program, led by ABC Education Coordinator Jenny Perez. We would like to acknowledge Jenny Perez, ABC Special
Projects Director Gayle Engels, and ABC Chief Science Officer Stefan Gafner,
PhD, for their contributions to this project.
By Hannah
Baumana and Lisa Carriggb
a HerbalGram Associate Editor
b ABC Dietetics
Intern (TSU, 2016)
Overview
Sesamum indicum (Pedaliaceae) is an annual
flowering plant with fuzzy, slender, oblong leaves that are arranged opposite
to one another on the stem.1,2 The plant reaches an average of two
to four feet (0.6-1.2 meters) in height and produces small, bell-shaped pink,
violet, or white flowers arranged closely to the stem. The plant produces
oblong seed capsules that contain many small oval-shaped seeds.1 There
are three color varieties of seeds: black, white, and red/brown. Sesamum indicum grows in well-drained
soil in warm or hot climates and does not tolerate frost or poorly draining soil.
It is, however, a robust plant that will grow in poor soil, drought, and high
heat conditions where most other crops will not.3
While the leaves of the plant are also edible, the
sesame plant is grown primarily for its seeds, and the oil
 pressed from the
seeds is an important commercial and medicinal product. Sesame seeds are
possibly one of the oldest seed crops known to humankind. The exact origins of
domestication are uncertain, but it is believed that sesame originated in
Africa, and its cultivation and use spread to Egypt, India, the Middle East,
and China.3 Currently, S. indicum is cultivated in dry tropical
and subtropical regions of Asia, Africa, and South America.1,4,5Phytochemicals and Constituents
Although small in size, the sesame seed is densely
packed with nutrients. Sesame seeds are rich in protein (approximately 20-25% by
weight) and oil (approximately 50% by weight). Sesame additionally contains
fiber, vitamin E, thiamine, riboflavin, niacin, and minerals, such as copper,
zinc, magnesium, phosphorus, iron, and calcium.6 Sesame oil contains
approximately 38% monounsaturated fat (MUFA) and approximately 44%
polyunsaturated fat (PUFA).7 The unsaturated fatty acids oleic acid
and linoleic acid account for the majority of the oil weight of the seed (more
than 800 g/kg). Sesame seeds are low in saturated fat.8 PUFAs have
anti-inflammatory, antithrombotic, anti-arrhythmic, lipid-lowering, and
vasodilatory properties.9,10
Sesame seed may be of particular interest to those
who follow vegetarian or vegan diets due to its amino acid and calcium contents.
Unusual for a plant-based protein source, sesame has a mostly complete amino
acid profile, missing only lysine. Sesame is rich in the amino acid methionine,
which is often the missing amino acid in legume-based diets.11 Calcium
is one of the predominant minerals found in sesame, along with manganese,
phosphorus, and iron. One ounce (28 grams) of whole toasted sesame seeds
contains approximately 28% of the daily value of calcium based on a 2,000-calorie
diet. In comparison, one cup of nonfat dairy milk contains approximately 31% of
the daily value of calcium. However, the bioavailability of the calcium content
in plant foods is very different than that of animal-based products. Although
the whole sesame seed contains a high amount of calcium, the degree to which
the body is able to absorb this calcium is not well-studied.
Other constituents present in sesame include oxalic
and phytic acids.7 These compounds may interfere with the absorption
of certain nutrients. In addition, consuming high amounts of oxalates, which
are derivatives of oxalic acid, may be problematic for individuals with a
history of oxalate kidney stones.
While sesame has robust macronutrient and micronutrient profiles, other
bioactive compounds present in the plant that have caught the attention of
researchers. These compounds include phytosterols and a group of antioxidants
known as lignans.9 Antioxidants are substances that can prevent or
slow down the damage that reactive oxygen species (ROSs) can inflict on cells.
Phytosterols possess similar chemical structures to cholesterol, which is not
found in plants. When present in sufficient amounts in the diet, phytosterols
have been shown to reduce cholesterol levels in the blood. The fat-soluble
lignans (e.g., sesamin, sesaminol,
sesamolinol, and sesamolin) are the most-studied compounds in the sesame
plant. Lignan glycosides, in which a sugar molecule is attached to a lignan,
are also present in sesame, but are found only in the whole seed, and not in
sesame oil. Although the lignan glycosides have no direct antioxidant role,
these compounds within sesame seeds can be converted in the body to form sesaminol and thereby function as antioxidants.12
Historical and Commercial Uses
The use of sesame as a food, medicine, and
component of spiritual or ritual practices dates back more than 4,000 years in
Egypt and the Middle East, spreading from these regions to India and Europe.1
In the Hindu tradition, the sesame seed represents immortality. In the
Babylonian Empire (located in present-day Iraq; 18th century to 6th century
BCE), sesame oil was used to make perfumes and medicine. Records reveal that
ancient Egyptians also used sesame as a medicine, and the oil was used for
ceremonial purification in 1500 BCE. Europeans first encountered sesame seeds
when they were imported from India during the first century CE, and sesame
seeds were brought to the United States from Africa in the 17th century.
Various preparations of the plant have been used
for medicinal purposes. In Ayurveda, a traditional medicine system of India
that has been practiced for millennia, powdered seeds were given orally in
combination with
 a warm sitz bath containing a handful of bruised seeds for
treatment of amenorrhea and dysmenorrhea.2 Topically, a poultice of seeds
was applied to ulcers, burns, and scalds, and sesame seed paste was combined
with ghee (clarified butter) to treat bleeding hemorrhoids. Sesame oil was
commonly used as a base for perfumed oils for anointing the body and hair, and
traditionally used as a hair wash to promote hair growth.
In traditional Chinese medicine, sesame is known as
a yin tonic, which moistens dry tissues and increases body fluids. Due to these
properties, the seeds were used to promote lactation in breastfeeding mothers.13
In Europe, the oil was rubbed onto eyelids or dropped into eyes for eye
complaints and also used internally for treating gonorrhea. The leaves of the
sesame plant were decocted and consumed to resolve bowel afflictions, such as
dysentery and cholera.2
In addition to its traditional medicinal uses, S.
indicum continues to be an important food and lends itself to being
prepared and used in a wide variety of ways. Grown predominately for sesame
oil, the seeds themselves can be eaten raw or roasted.14 When the
seeds are hulled, they can be easily crushed into a flour or ground further
into a paste. Hulled seeds are widely used in their ground form as a paste in
Eastern Mediterranean and Middle Eastern cuisines. In Europe and North America,
the seeds are mainly used for bakery products, such as sesame seed buns.
In most cultures, the seeds have traditionally been
roasted or baked before consumption or prior to oil extraction, a practice that
enhances the sweet, nutty flavor and aroma of the seed and produces darker-colored
oil. Traditionally, the sesame seeds are cold-pressed for oil. In European and
North American cultures, a hot-pressed and refined oil is more highly desired, since
this creates a colorless and neutral oil, which is better suited for cooking
and use in salad dressing.14 The young leaves of the plant can be
eaten in stews, a practice seen in Africa today.5 In Korea, the
leaves are used to make a kind of wrap eaten with meats and other vegetables. The
sesame cake (leftover plant material after the oil has been removed from the
seeds) is used for livestock feed and can serve as a subsistence food in times
of scarcity.2 In African and Asian cuisines, the seeds are used in
both sweet and savory dishes. With globalization, many cultural foods have
traveled from their continents of origin to become commonly consumed in the United
States and elsewhere. For example, tahini, or ground sesame seed paste, has
emerged from the Middle Eastern culinary tradition as a familiar grocery store
item in the United States.13
Modern Research
Current research investigating the potential
efficacy of S. indicum and its constituents covers a wide range of applications.
Research on sesame’s lignan content and inherent antioxidant potential is most
prolific, specifically on the synergy of action of the lignans in combination
with vitamin E.8 Additionally, there were a number of studies on S.
indicum published in 2016, adding to the body of evidence on the efficacy
of therapeutic use and effective dosage.
Cardiovascular Disease Risk Factors and Serum Lipid Profile
Oxidative stress and inflammation play a large role
in the development and progression of atherosclerosis. A cardioprotective diet
and exercise are an important part of prevention and treatment. Two types of
fats, polyunsaturated and monounsaturated fatty acids, are present in the
sesame plant and have been reported to lower cholesterol. Other potential
mechanisms for the cardioprotective effects of sesame have been described, and
sesame oil may have multiple constituents that affect the atherogenic process
in various ways.15
The fat-soluble lignans in sesame may affect fat in
the bloodstream and the ability of the liver to process fat, particularly
triglycerides. A group of researchers cultivated a sesame variety that
contained two times more sesamin and sesamolin than conventional sesame to observe
the effect of these two compounds on health parameters.16 The
results showed that consumption of these seeds compared to seeds of a
conventional sesame variety effectively increased activity of enzymes located
in the liver and involved in fatty acid oxidation. This increase was correlated
with a decrease in serum triglyceride levels. The researchers noted that it is
unclear if these effects are solely a result of the difference in concentration
in the fat-soluble lignans or if other compounds may be involved in the
observed physiological activity of the seeds.
A 2016 systematic review examined scientific literature
to discern the effect of dietary intake of sesame seed and its derivatives on
the lipid profile and blood pressure of hypertensive and dyslipidemic
individuals.6 Of the seven studies that fit the review criteria,
most were not randomized, and those that were did not describe the blinding of
participants or personnel. Five clinical trials on patients diagnosed with
hypertension found significant results for the reduction in both systolic blood
pressure (SBP) and/or diastolic blood pressure (DBP). Of the three studies that
included a lipid profile, two found significant reductions in total cholesterol
(TC) and low density lipoprotein cholesterol (LDL-c) levels and one found a
significant increase in high density lipoprotein cholesterol (HDL-c)
concentrations in the sesame treatment groups.
The dosage and administration of sesame to
medicated hypertensive patients varied across studies. Positive outcomes for
SBP (reduction by approximately 3%) and DBP (reduction by approximately 2%)
were noted with as little as 7.6 grams per day of encapsulated black sesame
flour, the use of sesame oil for 45-60 days, or 60 grams of encapsulated
sesamin taken for four weeks.
Two studies examining the use of sesame flour in
individuals with dyslipidemia found that it positively impacted lipid profiles.
The exact mechanisms are still being studied. The reviewers noted, however,
that further research with low risk of bias is necessary to obtain more
conclusive results, since the seven clinical trials reviewed contained a high
risk of bias.6
Both sesame seed and sesame oil have been studied
for their cardioprotective benefits. Daily supplementation with sesame oil was
shown to increase flow-mediated dilation levels, suggestive of an improvement
in the vascular function, after meals when compared to supplementation with
corn (Zea mays, Poaceae) or olive (Olea europaea, Oleaceae) oils in
hypertensive men receiving medication.17 Furthermore, a randomized,
double-blind, placebo-controlled trial showed supplementation with sesame paste
ground from unhulled seeds improved lipid profiles and atherogenic lipid
parameters in patients receiving treatment for type 2 diabetes.18 The
researchers concluded that in addition to drug treatment, dietary modification
using functional foods, such as sesame seeds, may have beneficial effects for
the prevention of cardiovascular and diabetes complications. Additionally, a
study using a substitution of 35 grams per day of sesame oil as the only edible
oil for 45 days in hypertensive women resulted in significant decrease in serum
TC, and SBP and DBP. However, this study was uncontrolled.19
Neurodegenerative
Conditions
While the underlying mechanisms remain unclear, sesame’s strong
antioxidant capacity may be protective against neurodegenerative disorders.
Antioxidant nutrients from food may play an important role in lessening the
consequences of oxidative stress in cerebral ischemia (a type of stroke) and
recirculation brain injury. Sesamin and sesamol have demonstrated the ability
to elevate levels of alpha-tocopherol (a form of vitamin E) in the plasma,
liver, and brain of rats, displaying an inhibitory effect on endogenous lipid
peroxidation as well as oxidative DNA damage in rat plasma and liver and
protective effects on hypoxia in neurons.12 Based on the strong
antioxidant activities of sesame, it could be considered neuroprotective
against cerebral ischemia and stroke, though further studies need to be
conducted in support of this.
Consumer Considerations
Although not common, there is
the potential for an allergic reaction upon consumption of sesame seeds or
sesame oil.20,21 Since allergic reactions are mainly due to protein
found in the seed, there may be no reaction or less of a reaction to the oil,
with the exception of cold-pressed oil. Cold-pressed oil may still contain
varying amounts of protein.
Individuals who are predisposed to kidney stones or
are chronically undernourished in calcium, vitamin D and phosphorus may
exercise caution and consider total dietary intake of foods high in oxalic
acid. Sesame seeds contain 1-2% oxalic acid, which may interfere with calcium,
magnesium, and protein absorption in the body.21,22 Additionally,
certain types of kidney stones are composed of oxalic acid. It is important to
note that the hull of the seed contains the highest amount of oxalic acid.23
The presence of oxalic acid can be reduced significantly through processing of
the seeds and in particular through sprouting the seeds prior to consumption.11
Cooking and toasting the seeds before consumption or pressing the seed for oil
also can reduce levels of oxalic acid and maximize the bioavailability of
sesame’s beneficial constituents.24 Additionally, some bioactive
constituents of sesame are found in highest amounts in sesame oil produced from
toasted or otherwise heated sesame seeds.
Nutrient Profile25
Macronutrient Profile: (Per 1 tablespoon
[approx. 9 grams] sesame seeds)
52 calories
1.6 g
protein
2.11
g carbohydrate
4.47
g fat
Secondary Metabolites: (Per 1 tablespoon
[approx. 9 grams] sesame seeds)
Very good source of:
Manganese:
0.22 mg (11% DV)
Good source of:
Calcium:
88 mg (8.8% DV)
Magnesium:
32 mg (8% DV)
Iron:
1.31 mg (7.2% DV)
Phosphorus:
57 mg (5.7% DV)
Also provides:
Thiamin:
0.07 mg (4.7% DV)
Dietary
Fiber: 1.1 g (4.4% DV)
Molybdenum:
2.66 mcg (3.6% DV)
Vitamin
B6: 0.07 mg (3.5% DV)
Niacin:
0.41 mg (2.1% DV)
Folate:
9 mcg (2.3% DV)
Potassium:
42 mg (1.2% DV)
Riboflavin:
0.02 mg (1.2% DV)
Trace Amounts
Vitamin
E: 0.02 mg (0.1% DV)
Vitamin
A: 1 IU (0.02% DV)
DV =
Daily Value as established by the US Food and Drug Administration, based on a
2,000-calorie diet.
Recipe: Sticky
Sesame Bars
Courtesy of Camilla
V. Saulsbury26
Ingredients:
Bars:
Chocolate
Drizzle:
Directions:
References
|
Tuesday, 14 March 2017
Food as Medicine: Sesame (Sesamum indicum, Pedaliaceae)
