Lecture 5: Fats Flashcards
What are the 4 types of fats?
-
Fatty acids
- Long chain of C’s and H’s with two ends -
Triglycerides
- Major form of fat in food and body
- 3 FA’s + glycerol -
Phospholipids
- Fat-related substances in all our cells
- Contain phosphorus, fatty acids, nitrogen -
Cholesterol
- Waxy lipid found in all our cells and in foods from animals
What are the 4 main categories of fatty acids?
- Saturated (full complement of hydrogen’s)
- Monounsaturated (one C=C double bond)
- Polyunsaturated (2 or more C=C double bonds)
-
Trans fatty acids (Unsaturated fatty acid where the H’s of the C=C double
bond lie on opposite sides of the C chain)
In the following name, what do the different numbers mean:
18:3n-_3_
- Number of C atoms
- Number of double bonds
- Position of first double bond from methyl end
What are essential fatty acids and give 2 kinds of them
= fatty acids that cannot be made in the Boyd but are needed for good health so must be consumed
Two kinds:
- Omega 3 fatty acids (anti-inflammatory; promotes blood thinning, artery dilation, lower blood pressure, etc)
- Omega 6 fatty acids (pro-inflammatory; promotes blood clotting, artery constriction, higher blood pressure, etc)
What are 7 functions of dietary fat?
- Provide fuel for cells
- Important for maintaining healthy skin, hair & eyes
- Precursors for hormones
- Help with good immune function
- Involved in inflammatory response (omega 3 reduces
inflammation) - Insulate organs from shock/damage
- Help control body temperature
How do fast get transported to cells?
Fat doesn’t dissolve in water/blood so it must be packaged into lipoproteins (made in the liver) for circulation.
Two kinds:
- LDL-cholesterol (low density; the “bad” one): cholesterol, triglyceride, transports cholesterol to the cells
- HDL-cholesterol (high density; the “good” one): mostly protein, picks up cholesterol from the cells and tissue and brings it back to the liver for excretion
What are the dietary recommendations for total fat and how do people in New Zealand compare?
- 15-30% of total energy (WHO/FAO Expert Consultation, 2010)
- 20-35% of total energy (Nutrient Reference Values for Australia and New Zealand)
–> it is the kind of fat intake that matters in relation to heart disease, not the amount
–> people in NZ are at the higher end of the NZ recommendations, but mostly still within range
What are dietary sources of total fat among NZ adults?
- Butter and Margarine (sandwiches and baked goods; 9%)
- Potatoes and kumara (crisps and chips; 6%)
- Bread-based dishes (6%)
- Poultry (6%)
- Beef and veal (5%)
- Milk (5%)
What are saturated fats?
- The carbon atoms in the chain hold as many hydrogen atoms as possible (full complement)
- Solid at room temperature (e.g. butter, bacon drippings)
- Sources include: (mostly animal products; whole milk, butter, cheese, red meat, chocolate, coconut, palm oil
- We all need some saturated fat (esp for hormone production) but excess consumption related to polyunsaturated fats associated with increased risk of heart disease
What are the dietary recommendations for saturated fat and how do people in New Zealand compare?
10% of total energy (including trans fats)
–> people in NZ are a bit above this, they are more between 12-14%
What are 10 sources of saturated fat among NZ adults?
- Butter and margarine
- Milk
- Bread-based dishes
- Cheese
- Potatoes, kumara and taro (chips and crisps)
- Cakes and muffins
- Poultry
- Beef and veal
- Dairy products
- Sausages and processed meats
What does the heart foundation say about dairy fat?
- Total dairy does not appear to be associated with an adverse effect on CVD or CHD and some studies suggest a beneficial effect.
- Reduced-fat dairy has been linked with reduced risk for some, but not all cardiovascular risk factors.
Recommendations:
- Choose mostly reduced-fat dairy options as part of a heart-healthy diet.
- Plant fats should be the predominant sources of fat in the diet.
What does the heart foundation say about coconut?
- 92% of fat in coconut is saturated
- Main fatty acid in coconut oil is lauric acid – this is different to
commercially produced MCTs. - Experimental research relates to coconut oil, observational studies link to coconut flesh, milk or cream.
- Studies found coconut did not raise cholesterol (total, LDL) to the same extent as butter, but increased cholesterol more than other plant oils
Recommendations:
For people in NZ it is preferable to use unsaturated plant oils rather than coconut oil as the main culinary oil.
What are two kinds of unsaturated fats and explain their difference
Monounsaturated fats:
- The carbon atoms in the chain hold two fewer hydrogen atoms (One double bond; C=C)
- Liquid at room temperature (e.g. oil)
- Sources include: olives and olive oil, canola oil, peanut oil, nuts, avocados
- Healthy sources of fat - protect against heart disease (ensure not oxidized; high fat frying)
Polyunsaturated fats:
- Carbon atoms in the chain hold even fewer hydrogen atoms than monounsaturated fatty acids (Two or more C=C bonds)
- Liquid at room temperature
- Sources include: corn, soybean, safflower and cottonseed oils, fish
- Essential fatty acids are polyunsaturated
- Healthy sources of fat - protect against heart disease (Ensure not oxidized; industrial seed oils, high fat frying)
What are the dietary recommendations for unsaturated fats?
-
MUFA: calculated from total – saturated – PUFA – trans
and may cover a wide range - POLY: 6-11% of total energy
- No RDI in NZ for mono or polyunsaturated fats but AI’s in
Aust NZ Nutrient Reference Values - Ratio of omega 6 to omega 3 may also be important; aim for more omega 3 - 5:1 may help prevent disease
What are Omega-3 fatty acids?
- Make up cell membranes in body, including eye, brain and sperm cells
- Involved in reducing blood clotting, contraction and relaxation of artery walls, and anti-inflammation
- Regular intake of eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) important for health and protection against heart disease
What are sources of Omega-3 fatty acids?
- Fatty fish – wild salmon, tuna, warehou, anchovies (EPA and
DHA aim for two serves/week) - Flax (linseed), some plant oils (canola, soybean)
- Walnuts, some other nuts, soybeans
What are the dietary recommendations for Omega-3?
- Goals range 1-2% of total energy
- Absolute recommendations vary with age and gender
- Don’t know safe upper limits of omega-3 intake for optimal health
What are Omega-6 fatty acids?
- Used in the synthesis of prostaglandins (hormone like substances)
- Deficiency is possible, but very rare
- Symptoms of deficiency include dry hair, hair loss, poor wound healing
What are the dietary recommendations for Omega-6?
- Goals range 5-8% of total energy
- Absolute recommendations vary with age and gender
- Don’t know safe upper limits of omega-6 intake for optimal health
What are dietary sources of omega-6 fatty acids?
- Nuts
- Cereals
- Whole-grain breads
- Vegetable oils
- Eggs and poultry
What are trans fatty acids?
- Created by hydrogenating plant oils
- The oils then have a higher melting point and a reduced tendency for oxidation, meaning longer shelf-life
- Oxidised fatty acids unhealthy - inflammation
- Trans fats are associated with greater risk of cardiovascular disease and have no known health benefit
- Food sources: margarine (lower in NZ than US), fast food, snack food, commercially prepared baked goods
What are the dietary recommendations for trans fats?
< 1% of total energy
What is cholesterol?
- Sterol that functions as a precursor of bile acids, steroid
hormones and vitamin D - High serum cholesterol is generally associated with cardiovascular disease (serum cholesterol increases with high saturated fat intake)
- Synthesized by body, so generally not essential to get from diet
- Dietary cholesterol only found in animal foods (e.g., eggs, beef and poultry)
What are the dietary recommendations for saturated fat and how do people in New Zealand compare?
Recommendation:
- Body produces cholesterol necessary for biochemical processes
- Population intake goal <300mg per day
- Dietary cholesterol generally not an issue unless at high risk of heart disease (often debated)
–> males are mostly higher in intake than the recommended amount (between 300-350), and females are below (between 200-300)
What are 5 ways to improve dietary fat choices?
- Avoid trans fats and balance saturated, mono, and polyunsaturated fats
- Use plant oils and avocado for cooking and dressings (be careful about oxidation from cooking and oil manufacture)
- Avoid ultra-processed foods
- Reduce processed foods and junk food
- Nuts, seeds, avocados, fish are good sources of healthy fats
