Transcript 1. Introduction to Natural Products Chemistry

4.1 Fats in Health and Commerce
RA Macahig
FM Dayrit
Introduction
•
Fats used to be a relatively uninteresting group of natural
products. However, they have recently returned to
prominence, particularly in two major areas of application:
o
As dietary fats: in nutrition and physiology
o
As biofuels
•
Fats occupy a metabolic position that covers both
“primary” and “secondary” metabolism. In this discussion,
we ignore this academic distinction.
•
This discussion is divided into the following sections:
1. Fats in the diet
2. Fats and biological membranes
3. Coconut and other oils
4. Biofuel future?
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1. Fats in the diet*
“To eat, or not to eat - fat is the question.”
- from the Introduction
Many of the dietary regulations being promoted in the US (e.g.,
USDA and FDA), as well as the fad diets (e.g., Atkins diet) are
erroneous. Despite its highly advanced food industry and high
levels of healthcare, the US is suffering from an epidemic of a
number of diseases and health conditions, such as coronary heart
disease, stroke, diabetes, obesity, immune dysfunction, and
mental illness.
* (from: Mary Enig*, Know your Fats: The Complete Primer for Understanding the Nutrition of
Fats, Oils, and Cholesterol, Bethesda Press, USA, 2000. Mary Enig is a biochemist and
nutritionist. She holds a Ph.D. in Nutritional Sciences from the University of Maryland and is a
Fellow of the American College of Nutrition. She has authored many journal articles on fats and
oils, and nutrient/drug interactions.)
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Interrelationships among Carbohydrates, Proteins and Fat in
Human Metabolism
Protein
Fat
Carbohydrate
Amino Acids
Glycogen
Triglycerides
Glycerol
Lactic acid
Glucose
Fatty Acids
Pyruvate
• Protein Fat
• Carbo  Protein
• Carbo  Fat
• Fat  Protein
• Pr, Carbo, Fat  Energy
Acetyl CoA
Krebs Cycle (TCA)
and Electron
Transport System
CO2, H2O, ATP
(http://www.faqs.org/nutrition/Met-Obe/Metabolism.html)
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Role of Fats in the diet and its impact on health
• Are saturated fats a risk factor for CHD?
Observed 15-year death rates per
100 men compared with death
rates from coronary heart disease
predicted from the multiple
regression on the ratio of
monounsaturated to saturated
fatty acids in the diets of
the cohorts: Seven Countries
Study (Keys et al. 1986).
Key to symbols: A: US railroad men; C: Crevalcore (Italy); D:, Dalmatia (Yugoslavia); E:, East
Finland; G: Corfu (Greece); H: Zutphen (Holland); K: Crete (Greece); M: Montegiorgio (Italy); R:
Rome railroad men; S: Slavonia (Yugoslavia); T: Tanushimaru (Japan); W: West Finland; U:
Ushibuka (Japan); V: Velika Krsna (Yugoslavia); Z: Zrenjanin (Yugoslavia)..
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• Coronary heart
disease (CHD): There
is no relationship
between the intake of
saturated fat from
coconut oil with
CHD.
“Vascular disease is uncommon in
both populations and there is no
evidence of the high saturated fat
intake having a harmful effect in
these populations.”
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• Cancer: High levels of
polyunsaturated fats are
correlated with higher
incidence of cancer.
Epidemiological data
suggest that coconut oil
is the most cancer
reducing oil.
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Role of Fats in the diet and its impact on health
• Immune dysfunction: Lipids play an important role in the
regulation of immune function. Diets high in omega-6 fatty
acids and partially hydrogenated fats have been reported to
adversely alter immune function. Diets high in coconut oil or
fish oil have been reported to improve immune response by
decreasing pro-inflammatory cytokines.
• Alzheimers: Axona® is an MCT oil (C8 and
C10) for the management of epilepsy and
Alzheimer's disease. MCTs produce ketones
which are an alternative energy source for
glucose in the brain. Coconut oil is also being
promoted for this ailment.
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Role of Fats in the diet and its impact on health
American dietary fat intake: 1930 vs 1985
Type of fat
1930
1985
% change*
Saturated
Monounsaturated
Polyunsaturated
Total
59 g (48%)
50 g (40%)
15 g (12%)
124 g
62 g (38%)
68 g (41%)
34 g (21%)
164 g
-21%
+2.5%
+75%
+32%
The biggest shifts in the American diet with regard to fats and oils since
WW II have been:
• The dramatic increase in consumption of polyunsaturated fats. Much
of this was pushed by the US soy bean industry lobby.
• The dramatic increase in consumption of unnatural fats and oils,
mainly partially hydrogenated fats and oils which produced trans-fats,
and more recently, synthetic fats, such as Olestra™.
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Fats and Obesity
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Fats and Obesity
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Role of Fats in the diet and its impact on health
Unnatural Fats in the Modern Diet
CO2H
CO2H
• Trans- fatty acids are not metabolized in
the same way as natural cis- fatty acids.
• Trans- fatty acids alter the characteristics
of membranes where they are incorporated.
• Developmental effects in infants.
• Change in reproductive functions.
• Trans- fatty acids are present processed food products (snack
chips, crackers, cookies, donuts, cakes, artificial coffee
creamers) that use partially hydrogenated oils.
• Shortenings and margarines with partially hydrogenated oils
have 25-50% trans-fatty acids.
9
9
Oleic acid, C18:1 cis-9
Elaicic acid, C18:1 trans-9
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Role of Fats in the diet and its impact on health
• trans-Fatty acids in the diet, created from partially
hydrogenating vegetable oils, have been implicated as
causing or exacerbating most of our modern diseases,
including heart disease, cancer, diabetes, obesity, immune
dysfunction and bone loss. (Mary Enig, Trans Fatty Acids in the Food Supply: A
Comprehensive Report Covering 60 Years of Research, 2nd Edition, Bethesda Press, 1995 )
• “Consumption of a solid fat rich in lauric acid gives a more
favorable serum lipoprotein pattern than consumption of
partially hydrogenated soybean oil rich in trans-fatty acids.
Thus, solid fats rich in lauric acids, such as tropical fats,
appear to be preferable to trans-fats in food manufacturing,
where hard fats are indispensable.” (de Roos et al., J. Nutr. 131 (2): 242,
2001)
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Role of Fats in the diet and its impact on health
Unnatural Oils in the American Diet
O
O
O
O
OO O
O
OO
O
O
O
O
OO
• Olestra is an artificial
sucrose polyester fat developed
by P&G to meet the “low-fat
low-calorie” craze in the US.
• Olestra is not metabolized by
the body (so it is a “zerocalorie fat”) and is excreted
unchanged (acts like an inert
solvent).
• Potential for nutritional
deficiency or imbalance,
among others. Adjunct
technology to high food
consumption.
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Role of Fats in the diet and its impact on health
Short-chain fatty acids and intestinal health
(from: Wikipedia)
• Short chain fatty acids (SCFA) are a sub-group of fatty acids with less than
eight carbons. This group includes: Acetic acid, Propionic acid, Lactic acid,
Butyric acid, Isobutyric acid, Valeric acid, Isovaleric acid, Caproic acid, and
Succinic acid.
OH
CH 3CO 2H
CH3CH 2CO 2H
CH 3CH 2CH 2CH 2CO 2H
CH3
CH3
CH3 CHCO2H
CHCH2CO2H
CH 3CH 2CH 2CO 2H
CH3
CH3
CH 3CH 2CH 2CH 2CH 2CO 2H
CHCO2H
HO 2CCH 2CH 2CO 2H .
• SCFAs are used by the intestinal mucosa or absorbed through the colonic wall
into the portal circulation (supplying the liver) that transports them into the
general circulatory system. The major SCFA in humans are butyrate,
propionate and acetate. Butyrate is the major energy source for epithelial cells
lining the colon (colonocytes); propionate is taken up by the liver; and acetate
enters the peripheral circulation to be metabolized by peripheral tissues.
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Role of Fats in the diet and its impact on health
• Collectively, SCFA have extensive physiological actions promoting health
effects, among which major functions are:
• stabilize blood glucose levels by acting on pancreatic insulin release and
liver control of glycogen breakdown
• stimulate gene expression of glucose transporters in the intestinal mucosa,
regulating glucose absorption
• provide nourishment of colonocytes, particularly by butyrate
• suppress cholesterol synthesis by the liver and reduce blood levels of LDL
cholesterol and triglycerides responsible for atherosclerosis
• lower colonic pH (i.e., raises the acidity level in the colon) which protects
the lining from formation of colonic polyps and increases absorption of
dietary minerals
• stimulate production of T helper cells, antibodies, leukocytes, cytokines
and lymph mechanisms having crucial roles in immune protection
• improve barrier properties of the colonic mucosal layer, inhibiting
inflammatory and adhesion irritants, contributing to immune functions
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Medium-chain fatty acids: C8, C10, C12
Refs:
Bach and Babayan, Am J
Clin. Nutr.,1982, 36, 950.
CS Dayrit, “Health
Aspects of Coconut Oil,”
Proceedings of the World
Conference on Lauric
Oils, TH Applewhite (ed),
1994.
“Abstract. Medium chain fatty acids (MCFA) are readily
oxidized in the liver….MCTs increase energy expenditure, may
result in faster satiety and facilitate weight control when included
in the diet as a replacement for fats containing LCT.”
Are all saturated fats unhealthy? (FMDayrit)
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2. Fats and biological membranes
In the past, lipids were simply considered as membrane components
and biological energy source. Today we know that the role of lipids is
much more complex. The biological membrane is made up of various
fatty acids which are ester-linked to a phosphatidyl group, such as:
Phosphatidylcholine (PC):
Phosphatidic acid (PA):
Phosphatidylinositol (PI):
Phosphatidylserine (PS):
Phosphatidylethanolamine (PE):
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2. Fats and biological membranes
Biological membranes
• Their composition and structure are not thought to have subtle
biophysical properties which result in heterogeneous membrane
domains. Membranes are also regarded as a reservoir for
precursors of molecular messengers. This could represent a
clue for understanding the molecular diversity observed in
membrane phospholipids.
• Biological membranes perform a complex multitude of tasks.
This complexity is reflected in the complexity of its
composition. For example, the human red cell which contains
only a plasma membrane contains about 300 molecular species
of glycerophospholipids formed by different long chain (C14–
C22) fatty acids.
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2. Fats and biological membranes
Lipids as functional biomolecules
Consider the role of phosphatidic acid (PA) in the cell. Its role can
be classified into three categories:
• PA is the precursor for the biosynthesis of all other acylglycerol
lipids in the cell.
• The physical properties of PA influence membrane curvature.
• PA is a signaling lipid, recruiting cytosolic proteins to
appropriate membranes.
PA concentrations are maintained at very low levels in the cell by
lipid phosphate phosphohydrolases (LPPs), which rapidly convert
PA into DAG. PA is, therefore, essential for lipid synthesis and
cell survival, yet, under normal conditions, is maintained at very
low levels in the cell.
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3. Coconut oil and other oils
The Coconut Palm (Cocos nucifera), is a member of
the family Arecaeae (palm family) and is the only
species in the genus Cocos. It is a large palm,
growing to 30 m tall.
The origin of the coconut is still undetermined. Various experts believe
that it may be native to Southeast Asia or South America. Fossils dating
more than 15 m years have been found in New Zealand and India.
Regardless of its origin, the coconut has spread across the tropics,
generally growing at 20 N/S latitude. (from: Wikipedia)
Zone 1: High coconut productivity
Zone 2: Medium
Zone 3: Low or none
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Some History, Facts and Myths
• Pre-history. Coconut oil has been traditionally used as food,
medicine and cosmetic throughout Asia and the Pacific for at
least 4,000 years.
• Spanish era. The government decrees the planting of
coconut trees throughout the Philippine islands.
• 1850. The English develop a copra milling process. Crude
coconut oil and copra are exported to the US for use as edible
oil.
• 1902. German chemist W. Normann patents (heterogeneous)
hydrogenation of vegetable oils. In 1911, Procter & Gamble
launched the first hydrogenated shortening, Crisco.
(http://en.wikipedia.org)
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Some History, Facts and Myths
• 1920-1940s. American Soybean Association (ASA) is
formed. During WW II, soya oil production is increased to
replace tropical oils which were blocked by the war.
(www.soygrowers.com)
• 1934. Henry Ford develops enamel coating for cars from
soya oil by free-radical polymerization process.
(www.thesoydailyclub.com)
• 1949. The export of US soya expands using US foreign
assistance programs. (www.soygrowers.com)
• 1987. ASA pressures US FDA to enact a “truth-inlabeling” campaign against “highly saturated tropical fats
in foods … (to) increase market share for soybean oil”.
(www.soygrowers.com)
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Some History, Facts and Myths
• 2006. In the 1990s, the Harvard School of Public Health
helped sound the alarm about trans fat and coronary heart
disease risk and advocated that it be explicitly listed on
food labels. In an updated analysis of the trans fat-heart
disease link, HSPH researchers found that removing transfats could prevent tens of thousands of heart attacks and
cardiac deaths each year in the US. (See: New England J. Med.,
April 13, 2006; ref: http://www.hsph.harvard.edu/reviews/transfats.html)
• 2006. US FDA amended its regulations to require that
trans-fatty acids be declared in the nutrition label. Further,
the agency withdrew the proposed footnote stating: “Intake
of trans-fat should be as low as possible.” This rule took
effect January 1, 2006. (http://www.cfsan.fda.gov/)
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Fats in World Commerce
(www.cyberlipid.org/glycer/glyc0005.htm)
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Are all saturated fats unhealthy? (FMDayrit)
29
Are all saturated fats unhealthy? (FMDayrit)
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4. Biofuel Future?
• Biofuels are broadly defined as fuels derived from biological
sources. These can be solid, liquid, or gas. Liquid biofuels
include bioethanol and biodiesel. Because of its use for
transportation, the biggest attention is focused on liquid
biofuels.
• Biofuels is one strategy being considered to reduce greenhouse
gas emissions and increase energy security for countries
without fossil fuels.
• Many issues and concerns have been raised regarding biofuels,
such as: cost and energy of inputs: labor, fertilizer, water; food
vs. energy; and impact on biodiversity due to land conversion.
• The main concern for us in this chapter is the use of vegetable
oil and biodiesel (transesterified vegetable oil, e.g., CME).
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4. Biofuel future?
Oil yields of common crops for
biodiesel use.
Crop
kg oil/ha liters oil/ha
corn (maize)
145
172
soybean
375
446
euphorbia
440
524
sunflowers
800
952
rapeseed (Canola)
1,000
1,190
jatropha
1,590
1,892
coconut
2,260
2,689
oil palm
5,000
5,950
Algae (actual yield)
6,894
7,660
39,916
47,500
Algae (theoretical yield)
Biodiesel refers to a dieselequivalent processed fuel
consisting of short chain alkyl
(methyl or ethyl) esters, made
by transesterification of
vegetable oils or animal fats,
which can be used (alone, or
blended with conventional
diesel fuel) in unmodified
diesel-engine vehicles.
(from Wikipedia)
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4. Biofuel future?
Palm
The African Oil Palm was introduced to
Sumatra and Malaya in the early 1900s;
many of the largest palm oil plantations
are now in this area, with Malaysia
growing over 20,000 km2 and the
largest producer with 51% of world
production.
For every 100 kilograms of fruit, 22 kg
of palm oil and 1.6 kg of palm kernel oil
can be extracted. This high productivity
– as high as 7,250 L/ha/yr – has has
made it the prime source of vegetable
oil in many tropical countries and
candidate for biofuels.
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4. Biofuel Future?
Jatropha
• Jatropha (family Euphorbiaceae) is a genus of
approximately 175 succulents, shrubs and trees
(some are deciduous, like Jatropha curcas L.).
Plants from the genus natively occur in Africa,
North America, and the Caribbean. It was spread
as a valuable hedge plant to Africa and Asia by
Portuguese traders.
• Because jatropha grows well in degraded soil
and drought conditions, it is suitable for soil
and watershed restoration. Its deep root
system makes it attractive for sloping
agriculture and protection against erosion.
4.1 Fats in Health and Commerce (Dayrit)
(www.jatrophaworld.org)
34
4. Biofuel Future?
• Jatropha has medicinal properties. Jatropha oil can
be used for candles and soap and the residual cake
can be used for compost or fertilizer. However, its
most attractive property is as a source of biofuel.
• J. curcas trees, also called physic nut, produce
1600 liters of oil per hectare. The seed yields 31 to
37 % of oil which is trans-esterified with MeOH to
yield the fatty acid methyl esters.
(www.daimlerchrysler.com)
Estimated yield of Fatty Acid oils
0-0.5%
12-17%
5-6%
37-63%
19-40%
Biodiesel yield=oil yield x 0.95 (approx.)
Crop
kg oil/ha
Corn
145
Jatropha
1,590
Coconut
2,260
Palm oil
5,000
4.1 Fats in Health and Commerce (Dayrit)
litres oil/ha
172
1,892
2,689
5,950
35
(www.svlele.com)
Fatty acid composition:
Myristic acid:
Palmitic acid:
Stearic acid:
Oleic acid:
Linoleic acid:
A Mercedes-Benz CClass tested jatropha
biofuel covering
around 5,900 kms
crossing India.
4. Biofuel Future?
Partial Lifecycle Analysis of Biofuels
Note: The various inputs and
outputs can be beneficial or
harmful.
Sunlight
H2O
Land
Chemicals Transport
Labor
Energy
Fertilizer
Labor
CO2
Labor
Energy
(N,P,K)
Agricultural
production
Biofuel
production
Commercial
fuel
Blending
Water
pollution
Other
products
Biomass
O2
Waste
products
Other
products
Biomass
4.1 Fats in Health and Commerce (Dayrit)
NOx
CO2
Particulates
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4. Biofuel Future?
Algae Biofuels
Biofuels from photosynthetic algae:
• Algae can be grown using land and water unsuitable
for plant or food production, unlike some other firstand second-generation biofuel feedstocks.
• Select species of algae produce bio-oils through the
natural process of photosynthesis — requiring only
sunlight, water, carbon dioxide and N-source.
• Growing algae consume carbon dioxide; this provides
greenhouse gas mitigation benefits.
• Bio-oil produced by photosynthetic algae and the
resultant biofuel will have molecular structures that
are similar to the petroleum and refined products we
use today.
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