Download DIETARY FAT

Dietary Reference Intakes
for
Total Fat, Fatty Acids and
Cholesterol for Adults
Paula R. Trumbo
DIETARY FAT
•
•
•
•
•
•
•
Total Fat
Saturated Fat
Monounsaturated fatty acids
n-6 Polyunsaturated fatty acids
n-3 Polyunsaturated fatty acids
Trans fatty acids
Cholesterol
200-01
1
Total Fat
• No recommended intake level set for
children and adults
• No defined dose response data to suggest a
specific recommended intake level (for either
meeting requirements or disease risk
reduction)
• The % of energy consumed as fat can vary
greatly while still meeting daily energy needs
• AI for infants based on average intake from
human milk and complementary foods
200-01
Saturated, Monounsaturated,
Trans Fatty Acids or Cholesterol
• No recommended intake levels
• Synthesized at adequate levels for
biochemical/physiological needs
(saturated and monounsaturated fatty
acids, and cholesterol)
• No known beneficial role in preventing
chronic diseases or deficiency symptoms
(saturated and trans fat and cholesterol)
2
n-6 Polyunsaturated Fatty Acids
Linoleic Acid
• Required
• A precursor to arachidonic acid – substrate for
eicosanoid production
• Component of membrane structural lipids
• Important in cell signaling pathways
Linoleic Acid is Required
n-6 PUFA Deficiency Characterized by:
• Rough, scaly skin, rash dermatitis,
increased transepidermal water loss
• Elevated eicosatrienoic acid: arachidonic
ratio (triene:tetraene ratio)
3
Elevated triene : tetraene ratio
With inadequate n-6 PUFA intake:
Arachidonic acid
Inhibition of desaturation of oleic acid
Synthesis of eicosatrienoic acid from Oleic acid
Signs of EFA deficiency
Triene
: tetraene ratio >0.4 (Goodgame et al., 1978, Holman, 1960;
C20:3 n-9 : C20:4 n-6
Jeppesen et al., 2000)
0.2 (Holman et al., 1991; Jeppensen et al., 1998)
EAR/RDA Not Set for Linoleic
Acid
Lack of dose-response studies in
“healthy” individuals
4
AI for Linoleic Acid
• AI is based on the median intake of linoleic acid
by different gender and life stage groups in the
United States, where the presence of n–6
polyunsaturated fatty acid deficiency is
nonexistent in the U.S. and Canada.
• AI set for infants based on average intake from
human milk and complementary foods
Criteria and AIs* for Linoleic Acid (g/d)
Life Stage
Criterion
0-6 m
7-12 m
1-3 y
4-8 y
9-13 y
14-18 y
19 - 50 y
> 50 y
Milk intake
Milk + other foods
Median intake
Median intake
Median intake
Median intake
Median intake
Median intake
Pregnancy
Lactation
Median intake
Median intake
Male
4.4
4.6
7
10
12
16
17
14
Female
4.4
4.6
7
10
10
11
12
11
13
13
*Assumed adequate to prevent EFA deficiency (rare in the U.S. and
Canada)
200-01
5
n-3 Polyunsaturated Fatty Acids
α-Linolenic Acid
• Required
• Play an important role in structural
membrane lipids
• Modulates the metabolism of n-6 PUFA and
influence the balance of n-6 and n-3 fatty acid
derived eicosanoids
n-3 PUFA Deficiency
• Data are from case reports of patients
receiving parenteral nutrition
• Clinical deficiency signs : peripheral
neuropathy and blurred vision (Holman
et al., 1982), scaly and hemorrhagic
dermatitis, hemorrhagic folliculitis of the
scalp, impaired wound healing and
growth retardation (Bjerve, 1989)
6
EAR/RDA Not Set for αLinolenic Acid
Lack of dose-response studies in
“healthy” individuals
AI for n-3 PUFA
• AI is based on the median intakes of α-linolenic
acid in the United States where the presence of n-3
polyunsaturated fatty acid (PUFA) deficiency in
nonexistent.
• Approximately 10 percent of the AI can come
from longer n-3 PUFAs (EPA and DHA)
• AI for α-linolenic acid for infants based on
average intake from human milk and
complementary foods
• EPA and DHA not considered essential
7
Criteria and AIs* for n-3 or α-Linolenic Acid
(g/day)
Life Stage
Criterion
Male
0-6 m
7-12 m
1-3 y
4-8 y
9-13 y
14-18 y
19 +
Pregnancy
Lactation
Milk intake
Milk + other foods
Median intake
Median intake
Median intake
Median intake
Median intake
Median intake
Median intake
0.5
0.5
0.7
0.9
1.2
1.6
1.6
Female
0.5
0.5
0.7
0.9
1.0
1.1
1.1
1.4
1.3
*Assumed adequate to prevent EFA deficiency (rare in the U.S. and
Canada)
200-01
No ULs Set for
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•
•
•
•
•
•
Total Fat
Saturated Fat
Monounsaturated Fat
n-6 Polyunsaturated Fats
n-3 Polyunsaturated Fats
Trans Fat
Cholesterol
WHY?
200-01
8
• There are no UL’s set for Total Fat, Fatty
Acids and Cholesterol because there are
insufficient data to use the model of risk
assessment to set a UL for total fat,
monounsaturated fatty acids, and n-6 and n3 polyunsaturated fatty acids
Dietary Reference Intakes
UL
RDA
AI
0.5
0.
5
Risk of excess
Risk of inadequacy
EAR
Observed level of intake
Increase
196-02
9
Calculated Changes in Serum LDL Cholesterol
Concentration in Response to Percent Change in
Dietary Saturated Fatty Acids
Change in LDL Cholesterol (mg/dl)
60
Mensink and Katan (1992)
Hegsted et al. (1993)
Clarke et al. (1997)
Mean
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
Saturated Fatty Acids (% energy)
Trans Fatty Acid and Saturated Fat
Intake and LDL:HDL Cholesterol Ratio
____ TFA
- - - - SFA
10
Increasing Intake of Cholesterol on
Serum Total Cholesterol
3
Defined Diets (Data from Table 1)
Self-Selected Diets (Data from Table 2)
Change in Serum TC (mmol/L)
2.5
Linear (Defined Diets (Data from Table 1))
Linear (Self-Selected Diets (Data from Table 2))
2
1.5
y = 0.0008x + 0.1737
R 2 = 0.1844
1
y = 0.0004x + 0.0108
R 2 = 0.1942
0.5
0
-0.5
-1
0
200
400
600
800
1000
1200
Change in Dietary Cholesterol (mg/d)
The UL should be 0-2%
• For cholesterol, this would be
recommending a vegetarian diet
• For trans fat, this would require the
reformulation of a number of foods
• For saturated fat, this would be difficult
to achieve
11
Fatty Acid Composition of Common Fats and Oils
Canola Oil
Flaxseed Oil
SFA
Walnut Oil
MUFA
Corn Oil
Omega-6
Omega-3
Olive Oil
Peanut Oil
Beef Tallow
Butter (dry basis)
0%
20%
40%
60%
80%
Fatty Acid content normalized to 100%
100%
Ref: USDA Nutrient Database, release 15
Minimum Saturated Fat (%) Intake Needed for
Levels of n-3 and n-6 Fatty Acids
Non-vegetarian Menu
Vegetarian Menu
n-3 = 0.6%
n-3 = 1.2%
n-3 = 0.6%
n-3 = 1.2%
Total Fat (%)
n-6 = 5%
n-6 = 10%
n-6 = 5%
n-6 = 10%
20
2.8
2.7
2.7
2.6
25
3.6
3.2
3.6
3.2
30
4.3
3.9
4.3
3.9
35
5.0
4.5
4.9
4.5
The requirements for n-3 and n-6 fatty acid intake can
be met with low levels of saturated fat intake (3-5%)
12
Recommendation
Minimize Saturated and Trans
Fatty Acid and Cholesterol
Consumption while Consuming
a Nutritionally Adequate Diet
200-01
Acceptable Macronutrient
Distribution Range (AMDR)
Range of Intakes for an EnergyYielding Macronutrient that is
Associated with Reduced Risk of
Chronic Disease while Providing
Adequate Intakes of Essential
Nutrients
13
Endpoints Considered
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•
•
•
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Coronary heart disease (LDL, HDL, TG)
Stroke
Diabetes
Cancer
Obesity
Nutritional adequacy at low and high intake
levels
Macronutrients and Chronic Disease
The is a continuum in increased/decreased
intake, and risk of chronic disease
Macronutrients (fat and carbohydrate) and
interrelated
Not possible to set a defined level for % of
energy
14
Results of Meta-analyses Total Fat, TAG, HDL-C
50
ΔTAG = 40.22 -1.32 (%Dietary Fat), R2 = 0.34, p < 0.0001
40
30
Change from baseline (%)
20
10
0
10
20
30
40
50
-10
60
Total Fat in Diet
(% of energy)
-20
-30
-40
ΔHDL = -17.2 + 0.45 (%Dietary Fat), R2 = 0.29, p < 0.0008
-50
% change in TC:HDL-C ratio
Relationship between Changes in Total Fat
Intake and TC:HDL-C Ratio
25
20
15
10
5
0
-5
-10
-15
-20
-25
R2 =
0.3779
10
15
20
25
30
35
40
45
50
Dietary Total Fat (% en)
15
AMDR for Fat and Carbohydrate
• High fat/low carbohydrate
• Increased energy intake, increased saturated fat
intake = increased weight gain and CHD risk
• Low fat/high carbohydrate
• Reduced HDL, increased total cholesterol:HDL ratio
and triglycerides = increased risk of CHD
N-6 Polyunsaturated Fats
• AMDR set at 5-10 % of energy intake for linoleic
acid
– Lower boundary meets the AI recommendation
– Individual dietary intakes of linoleic acid in North
America rarely exceed 10% energy
– Epidemiological evidence for safety of intakes greater
than 10% of energy is lacking
– High intakes of linoleic acid create a pro-oxidant state
that may pre-dispose an individual to several chronic
diseases – CHD and cancer
16
Omega-3 Fatty Acids
• EPA and DHA appear to beneficial for heart
disease
• Concern about setting a separate AMDR for EPA
and DHA because of
-potential adverse effects at unknown levels
-Supplement industry provide EPA and DHA
to fill the void between current intake and
beneficial levels
AMDR for α-Linolenic Acid
• AMDR set at 0.6 to 1.2 % of energy intake
– Approximately 10% of the range can be
consumed as EPA and/or DHA
– Lower boundary of the range meets the AI for
α–linolenic acid
– Upper boundary represents the highest levels of
α-linolenic acid intake consumed in the form of
foods by individuals in North America
17
Acceptable Macronutrient Distribution Ranges
Range (percent of energy)
Macronutrient
1-3 yrs
4-18 yrs
Adults
Fat
30-40
25-35
20-35
n-6 linoleic acid
5-10
5-10
5-10
n-3
α-linolenic acid
Carbohydrate
0.6-1.2
0.6-1.2
0.6-1.2
45-65
45-65
45-65
Protein
5-20
10-30
10-35
*Approximately 10% of the total can come from longerchain n-3 fatty acids.
Example of Amount by Weight of
Macronutrients in a 2,000 kcal Diet
Nutrient
AMDR
Fat
20–35%
Linoleic acid
5–10%
α-Linolenic acid 0.6–1.2%
Protein
10–35%
Carbohydrate
45–65%
Selected Amount
30%
7%
0.8%
15%
55%
Amount for
2,000 kcal
67 g
16 g
1.8 g
75 g
275 g
18