Topic 4.3: Fats

Total Fat and Saturated Fat DRI

AMDR: %%20-35%%% of total calories from fat

* less than %%10% of total calories%% comes from %%saturated fat%%

Trans Fat World Health Organization

* %%less than 1%%% of total calories comes from %%trans-fatty acids%%

Cholesterol DRI

* %%as low as possible%% while consuming a nutritionally adequate diet
* the 2019 Canadian dietary guidelines do not provide intake for dietary cholesterol

functions of Dietary Fat

1. %%supply a concentrated nutrient of energy%%
* 9kcal/g
2. %%supply fat-soluble nutrients%%
* essential fatty acids (linoleic acid and a-linolenic acid)
* vit. A, D, E and K
3. %%increase the flavour and palatability foods%%
4. %%contribute to satiety%%
5. %%provide building blocks of cell membranes%%
* fats give cell membranes flexibility
6. %%body fat provides protection%%

lipids

* a family of __organic compounds__ soluble in *organic solvents* but not in water


1. trigylcerides (fats and oils)
2. phospholipids
3. sterols

facts about fats

* the degree of unsaturation influences the $firmness of fats at room temperature$
* saturated fats are solid (i.e., butter)
* unsaturated fats are usually liquid (i.e., oil)

triglycerides

* monoglycerides
* diglycerides
* triglycerides $(95$

fat variety

1. saturated fats
2. unsaturated fats
* monounsaturated
* polyunsaturated
* “cis form”
* “trans” form

saturated fatty acids

* have a %%maximum number of hydrogen%% possible
* %%solid%% at room temperature

unsaturated fatty acids

* %%less hydrogen%% are unsaturated
* %%liquid%% at room temperature
* most unsaturated fats come from %%plant based foods%%
* %%“monounsaturated”%% if one bond is unsaturated
* %%“polysaturated”%% if two or more bonds unsaturated

essential fatty acids (EFA)

* $polyunsaturated$
* raw materials for $eicosanoids (act like hormones)$
* affect: • Muscle contraction and relaxation • Blood vessel dilation and constriction • Blood clot formation • Blood lipid regulation • Immune response (includes inflammation)

two essential fatty acids

* linoleic acid %%(omega 6 fatty acid)%%
* alpha-linolenic acid %%(omega 3 fatty acid)%%

linoleic and linolenic acid

1. linoleic acid

* arachidonic acid


2. linolenic acid

* %%DHA%% (docosahexaenoic acid)
* EPA (eicosapentaenoic acid)

%%fish oils%% are a good source of DHA and EPA

omega-6 (ω-6) fatty acids

* linoleic acid is an $essential fatty acid$ from the $omega-6 family$


2. linoleic acid is required for:

* growth
* maintenance of healthy skin
* normal functioning of the reproductive system

omega-6 (ω-6) fatty acids continued

physiological importance of linoleic acid derivatives:

* found in cell membranes
* high amounts in $nerves and the brain$
* components involved in regulating blood pressure and blood clotting

food sources include:

* $sunflower, corn and soybean oils$

omega-3 (ω-3) fatty acids

* a-linolenic acid is an %%essential fatty acid from the omega-3 family%%
* a-linolenic acid (ALA), eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) are the primary members of the omega 3 family

omega-3 (ω-3) fatty acids continued

* physiological importance of
* a-linolenic acid:
* required as a structural component of cell membranes
* found in high concentrations in the $brain and eyes$
* a precursor for compounds that regulate blood pressure and clotting \[critical for Cardiovascular Health\]

food sources include:

* $walnuts, flax seed, canola oil, and soybeans$

fat in fish

* DHA and EPA have %%4-6 double bonds%% which gives them a very %%high degree of unsaturation%% making these fluid at cold temperatures (flexible)
* DHA and EPA form biologically active compounds to reduce blood pressure and tendency of blood to clot

benefits of fat in fish

the benefits derived from regular consumption of ω-3 fatty acids from fish sources include:


1. ↓%%risk of heart attack%%
2. ↓%%plaque formation in arteries%%
3. ↓%%incidence of high blood pressure%%
4. ↓%%risk of stroke%%
5. %%protection against irregular heart beat & sudden
death%%

modifying fats

* unsaturated fats are unstable
* turn rancid with time, oxygen and heat
* the solution is $“hydrogenation”$

hydrogenation

* a process by which $hydrogen is added to liquid unsaturated fats$ making them more saturated and solid
* shelf life, cooking properties, and taste are improved

drawbacks of hydrogentation

1. hydrogenated vegetable oils have more $saturated fat$
2. hydrogenation changes the structure of the unsaturated fatty acids, converts some fats into trans fats

trans orientation

* Cis-fatty acid (U shaped)
* Trans fatty acid (Linear)

trans fatty acids

* trans fatty acids raise %%LDL blood cholesterol%% levels more than dietary cholesterol, saturated fats or %%any other type of fat%%
* trans fats are preferred for use in margarine, snack foods, bakery products, and fried foods; they are more stable and have longer shelf life

recommendations for trans fats

1. Health Canada

* %%no safe level of trans fat%%
* recommends Canadians consume %%as little trans fats%% as possible
* %%research 2% ↑ intake = 23% ↑ CVD%%
* %%banned partially hydrogenated oils%% (PHOs) in order to reduce risk of CVD for Canadians (2018)

phospholipids

* components of cell membranes
* consist of a glycerol backbone with two fatty acids and a compound that contains phosphate

sterols

* large complicated %%ring carbon molecules%%
* sterols are found in both plant and animal foods
* chole**sterol** found *only* in %%animal products%%
* tasteless, odorless, clear liquid contained in lean and fat animal products

cholesterol fats and functions

1. %%found in every cell in your body%% (cell membranes)

* serves as the building block for %%estrogen, vitamin D and testosterone%%
* major component of %%nerves and the brain%%
* cannot be used for energy
* examples of cholesterol: butter, egg yolks, meat, whole milk, and poultry

cholesterol intake

no evidence that cholesterol is required in the diet


1. %%body produces enough cholesterol%%

* serum cholesterol comes from two sources
* 2/3 produced by the liver
* 1/3 comes from the diet


2. %%If diet is cholesterol free, people do not develop a cholesterol deficiency%%

* thus cholesterol is *not* an essential nutrient
* no recommended level of cholesterol intake
* blood cholesterol levels do increase as consumption increases, %%so intake should be minimal%%

phytosterols

plant based

* sterol ring structure


* stigmasterol

trends lead to revised thinking

1. people lose weight on

* high or low fat diets
* high or low carbohydrate diets
* high or low protein diets


2. weight depends on

* dietary changes & acceptability of these changes

Mediterranean Diet

* %%40% of calories from fat,%% mostly monounsaturated fat
* followers of the Mediterranean diet are

• physically active

• normal weight or lean

• have low rates of heart disease & cancer

• have a %%long life expectancy%%

choosing fats

low vs. regular fat food

* contain %%less fat than regular%%
* products may not contain good fat