Kin 232- Dietary fats and health

What is dietary fat?

Fat in the food we eat

Why is dietary fat important? (3)

1. Dense source of energy 2. Provides essential fats 3. Rich source of Vitamins A, D, E, K (fat-soluble vitamins)

How many kcals/g fat?

9Kcal/g fat (highest kcal/g source, good to help ppl gain weight)

What do fats do to food?

Makes food highly palatable!

Which type of fat is highly processed/ not good?

Trans fats

What are the three main types of lipids?

Triglycerides (TG), sterols, phospholipids

What are triglycerides made up of?

One glycerol molecule & three fatty acids

What are the different types of fatty acids found in triglycerides?

Saturated fatty acids, cis monounsaturated fatty acids, cis polyunsaturated fatty acids, and trans fatty acids

What type of fatty acid is being removed from the food system?

Trans fatty acids

What are two types of cis polyunsaturated fatty acids?

Omega-3 fatty acids and omega-6 fatty acids

What is an example of a sterol?

Cholesterol

What is an example of a phospholipid?

Lecithin

What happens in the mouth for fat digestion?

Mechanical & chemical breakdown → chewing & enzyme lingual lipase → initiates breakdown of triglycerides into diglycerides and free fatty acids

What happens in the small intestine for fat digestion?

Partially broken down droplets arrive → Bile salts emulsify fats, enhancing their surface area for further digestion → Pancreatic lipase breaks the units into free fatty acids, glycerol, cholesterol & phospholipids for absorption

What happens to the breakdown products of fats?

Repackaged as chylomicrons within intestinal cells (enterocytes) to help with transport, large chylomicrons enter the lymphatic system before being released into the bloodstream

Where do fatty acids go?

delivered to adipose tissue for storage or muscle cells for energy

Where are phospholipids found in food?

Found naturally in some foods (eggs, liver), added to others as emulsifiers (salad dressings)

What are phospholipids composed of?

Fatty acids, a phosphate group and a glycerol backbone (some may include alcohol as part of their structure)

Where are phospholipids found in the body?

In all biological membranes in the body → allow absorption of substances across the cell membrane (controls what does in and out of the cell), maintain membrane fluidity and integrity

What are the 3 different types of sterols, and which one is the most common?

Animal Sterols, Plant Sterols & Fungi Sterols → Animal sterols = most common

What are some examples of animal sterols?

Cholesterol found in eggs, meat, poultry, cheese, milk

Can sterols be synthesized in the body?

Yes → we are not dependent on dietary sources

What do sterols do in the body?

structural component of cell membranes; aids in the repair and formation of new cells; necessary for synthesizing steroid hormones (e.g., testosterone) and bile acids

What do plant sterols do?

similar in structure to cholesterol (*animal sterol), interfere with the body's absorption of cholesterol in the intestines → interference can help lower LDL cholesterol levels and may contribute to improved heart health (Ex of PS: becel, flora, pro-active)

What are Lipoproteins/ what is their role?

Particles in the bloodstream that transport cholesterol, triglycerides, & other fats (lipids) throughout the body, they differ in density and function, and they play distinct roles in cholesterol transport and metabolism

What are the 3 different types of lipoproteins?

VLDL → very low density lipoprotein, LDL → Low density lipoprotein, HDL → High density lipoproteins

Where are VLDL produced, & what do they do?

Produced by the liver, carries cholesterol and TG from the liver to other tissues in the body where they are needed, once it delivers TG to the cells, it becomes LDL

What do LDLs do?

"bad cholesterol" → carries cholesterol to tissues that need it (e.g. to build cell membranes, produce hormones), excess LDL in the blood can deposit cholesterol in the walls of arteries, forming plaques → causing atherosclerosis (hardening of the arteries → ↑BP), increasing the risk of heart attacks & strokes/TMAs

What do HDL do?

"Good cholesterol" → scavenger molecule, collects excess cholesterol from the bloodstream, tissues, and plaques in arteries, transports it back to the liver for recycling (to make bile acids or new cholesterol) or elimination from the body

What's typically on a blood panel in BC for lipids?

Cholesterol, LDL, HDL, Chol/HDL (risk ratio), Non-HDL, TG

What are the recommendations/findings for dietary cholesterol?

Research shows that dietary cholesterol (e.g., from eggs → 2/day is fine) has a minimal impact on blood cholesterol levels for most people, but individuals with CVD, diabetes, or familial hypercholesterolemia should still limit dietary cholesterol

What significantly raises LDL & VLDL?

Saturated fats, trans fats, and sugary foods

What are 2 recommended diets to lower cholesterol?

NCEP Step II Diet: Low-fat (<30% of total calories), low-cholesterol diet (< 200mg/day) with strict limits on saturated fat (<7% of daily calories), Portfolio Diet: Plant-based approach featuring nuts, soy, soluble fibre, and plant sterols (similar to Mediterranean diet)

What are saturated fats?

A type of fat molecule that has no double bonds between carbon atoms in its fatty acid chains, meaning it is "saturated" with hydrogen atoms (no fluidity/flexibly)

What are animal and plant sources of saturated fats?

A → Red meat, poultry skin, butter, cheese, and full-fat dairy, P → Coconut oil, palm oil, and cocoa butter

What are the physical and stability characteristics of Saturated fats?

physical → typically solid at room temperature, Stability → More resistant to oxidation compared to unsaturated fats, which means they have a longer shelf life + are better to cook with

How do saturated fats affect cholesterol?

↑ LDL cholesterol, may contribute to ↑ risk of cardiovascular diseases when consumed in excess over time

What are the dietary guidelines for saturated fats?

Limit saturated fat intake to less than 10% of total daily calories (may be an exception when in comes to SF in dairy → new research showing different effects with SF in dairy)

Cochrane Review: Saturated Fat & CVD Risk?

Reduction in Saturated Fat → 21% reduction in the risk of CVD (including heart disease and strokes), Impact on Cholesterol: Lowering saturated fat typically reduces serum total cholesterol levels, which is associated with a reduced risk of cardiovascular events

Cochrane Review: Healthy Population vs. At-Risk Individuals?

Both healthy and at higher risk individuals (e.g. those with hypertension, high cholesterol, or diabetes) benefit from reducing saturated fat intake; health benefits arose from replacing saturated fats with polyunsaturated fat or starchy foods (have fibre)

Cochrane Review: Replacement of fat matters?

The health benefits of reducing saturated fat are more pronounced when these fats are replaced with healthier options, such as polyunsaturated fats (found in fish, nuts, and vegetable oils) or whole grains VS replacing saturated fats with refined carbohydrates or sugars

What are Polyunsaturated fats (PUFAs)?

Fatty acids that contain carbon-carbon double bonds, not completely saturated with hydrogen atoms (more fluidity)

Polyunsaturated fats: what are essential fats?

Needed for optimal health, but generally in smaller quantities compared to other macronutrients

What are the functions of Polyunsaturated fats (3)?

Epithelial Cell Function, Regulation of Gene Expression, Synthesis of Eicosanoids

PUFAS: Epithelial cell function?

Essential fatty acids play a role in maintaining the integrity and function of epithelial cells, which line blood vessels and organs

PUFAS: Regulation of Gene Expression?

Fatty acids are involved in the regulation of gene expression, impacting various physiological processes

PUFAS: Synthesis of Eicosanoids?

PUFAs are precursors to eicosanoids (signalling molecules that can modulate pain, inflammation, and other bodily functions)

2 main types of Polyunsaturated fats?

Omega 3 & Omega 6

What are the 3 main Omega-3s?

EPA, DHA & ALA

What do omega-3s do, and what are examples of foods with them?

Anti-inflammatory - important for brain and heart health, found in Fatty fish, flax and walnuts

What are the dietary recommendations for ALA (Alpha-Linolenic Acid)?

About 1.1g/d for women and 1.6g/d for men (1tbsp flax = 2.4g ALA)

What are the dietary recommendations for EPA & DHA?

Specific daily values aren't set, but consuming 2 servings of fatty fish per week (like salmon, mackerel, or sardines) is recommended

What is the main Omega-6?

Linoleic Acid

Dietary recommendations for Omega-6/Linoleic Acid?

Essential but should be consumed in balance with omega-3s to avoid promoting inflammation, common in Western diets, found in Vegetable oils e.g. sunflower + corn oil

Omega-3 Index biomarker of long-term omega-3 FA status → what is it/what is a good level?

Blot spot analysis, 8 and over → good level

Inflammation?

Body's natural response to injury or infection. It involves immune cells, blood vessels, and molecular mediators (everyone has a little bit)

Acute Inflammation?

Short-term response, typically beneficial (e.g., redness, heat, swelling) → not concerning

Chronic Inflammation?

Prolonged, low-grade inflammation that can last for months or years, often without a clear trigger → concerning, hard to figure out the cause

Diet influences on inflammation?

Diets high in refined carbohydrates & saturated fats may exacerbate inflammation, diets rich in fruits, vegetables, whole grains, and omega-3 fatty acids can help reduce inflammation

How to lower inflammation using diet?

Mediterranean diet → Emphasizes healthy fats (olive oil, nuts), lean proteins, and a variety of fruits and vegetables, linked to reduced inflammation and lower disease risk

Chronic inflammation & disease links (5)?

1. CVD - atherosclerosis (build up of plaque in arteries), leading to heart attacks and strokes 2. Metabolic Disorders - Ex: obesity and type 2 diabetes associated with chronic low-grade inflammation, affecting insulin sensitivity 3. Cancer - Inflammation can promote tumour growth and metastasis. Certain inflammatory markers are used to assess cancer risk 4. Neurodegenerative Diseases - Ex: Alzheimer's disease → associated with chronic inflammation in the brain, contributing to neurodegeneration 5. Arthritis and Joint Disorders - Chronic inflammation plays a role in conditions like osteoarthritis and rheumatoid arthritis, causing pain and joint damage

What are the 4 fat-soluble vitamins?

A, D, E, K - absorption enhanced by fats

Vit A: Function, RDA, Found in?

F: Vision, teeth, bones, skin, RDA: M = 900mcg, W= 700mcg, Found in: Liver, fish, sweet potato, carrot, pumpkin seeds

Vit D: Function, RDA, Found in?

F: Bones, muscles, immunity, RDA: 600IU, Found in: Small amounts in fish & fortified foods

Vit E: Function, RDA, Found in?

F: Antioxidant, Skin, Immune system, RDA: 15mg, Found in: Sunflower seeds, almonds, fish

Vit K: Function, RDA, Found in?

F: Bones, Blood clotting, RDA: M = 120mcg, W=90mcg, Found in: Dark green leafy vegetable (k1)

Recommendations for dietary fat intake?

1. Limit the amount of fat to 20 - 35% total energy or have a small amount (2 to 3 Tbsp) of healthy fat each day and (<10% total energy from saturated fat /day), 2. Increase intake of polyunsaturated fats

How to limit amount of fat?

Replace most saturated fat with mono and polyunsaturated fat, Aim to steam, roast, boil or bake foods where possible to limit fat use, Flavour food with garlic, lemon, vinegars, herbs and spices rather than extra fats

How to increase polyunsaturated fats?

Eat fish twice per week, Chia, ground flax, nuts, seeds on salads, cereal etc. 1-2 tbsps. per day, consider an EPA / DHA supplement (FDA recommends not exceeding 2g/day DHA and EPA as supplements)

Body fat types (4)?

Adipose Tissue, Subcutaneous fat, Visceral fat, Intramuscular triglycerides

Adipose tissue: location, function, health consideration?

L: throughout body, F: Primary fat storage, insulation, cushioning, HC: Excess can lead to obesity & related diseases

Subcutaneous fat: location, function, health consideration?

L: under the skin, F: Insulation & energy reserve, HC: Considered less harmful than visceral fat

Visceral fat: location, function, health consideration?

L: Around organs/midsection, F: Protection of organs, HC: Linked to higher risk of metabolic syndrome & heart disease

Intramuscular Triglycerides: location, function, health consideration?

L: Within muscle tissue, F: Readily available energy source during exercise, HC: Excess may indicate insulin resistance

When is fat good for fuel vs carbs?

Fat → good for a long time, light to carry (not stored with H2O, 9kcal/g, Carbs → good for a short time (sprint), 4kcal/g

What are the ketogenic diet recommendations?

Overall: ↑ fat, ↓ carbs, Fat = 70-80%, Carbs = 5-10%, Protein = 20-25%, Total carbs per day = 20-25g

What are Ketones?

metabolic substrates produced in the liver in response to

starvation / very low carb intake, an alternative energy source for various tissues, including the brain

What are the 3 types of ketone bodies?

1. Acetoacetate 2. B-hydroxybutyrate 3. Acetone

Acetoacetate?

first ketone body produced, which can be converted into the others (measured in urine)

B-hydroxybutyrate?

used as a primary energy source by tissues, including the brain (circulation + urine)

Acetone?

by-product that is less commonly used for energy; it can be detected in breath and urine

How do fatty acids turn into ketones?

Fatty acids → Acetyl-CoA → Ketones → circulation

What are normal and ketosis ketone levels?

Normal= 0.5mmol/L, Ketosis= > 1mmol/L

What is ketosis?

A normal metabolic state that occurs with a ketogenic diet or fasting, generally safe for healthy individuals

What is ketoacidosis?

A dangerous condition that can occur in uncontrolled diabetes (T1), where ketone levels rise significantly, leading to a dangerous drop in blood pH (can lead to diabetic coma)

What is the body's initial response to ketosis?

↓ circulating glucose, subsequently insulin ↓ allows for increased mobilization of fat, ↑ catecholamines (e.g. epinephrine) and cortisol = ↑ Glycogenolysis and Lipolysis (breakdown of glycogen & fat)

What is the body's response to ketosis 2-3 days in?

↑ gluconeogenesis (glucose from non-carb source) from protein breakdown and glycerol from lipolysis, liver glycogen stores are typically depleted after 2-3 days, gluconeogenesis from protein is necessary, body will prioritize minimizing muscle loss by transitioning to ketones as the primary fuel source

5 adaptations to the ketogenic diet?

1. Adaptation ~3 weeks - some ppl will adapt faster 2. ↑ Ketogenesis provides fuel for the brain can derive a significant portion of its energy from ketones (up to 70% or more) 3. Lipolysis continues - producing glycerol + fatty acids. Fatty acids can be used directly for energy or converted into ketones 4. Gluconeogenesis continues - primarily from glycerol as ↓ rate of protein breakdown (need a small amount of glucose always) 5. Thyroid hormone T3 falls = ↓ metabolic rate (a natural response as the body adjusts to a different metabolic state)

What happens if you accidentally eat more carbs than recommended on the ketogenic diet?

lost progress very quickly- leave ketosis

Who might the ketogenic diet be useful for?

Drug-resistant epilepsy - shown to significantly reduce seizure frequency and severity, Obesity: can promote weight loss and fat loss, particularly visceral fat, by reducing appetite and increasing fat oxidation (last report + need an exit strategy), T2 Diabetes: helps improve blood sugar control and insulin sensitivity, leading to better management of diabetes, Metabolic Syndrome: Individuals with components of metabolic syndrome (e.g., high blood pressure, high triglycerides) may benefit from improved markers through weight loss and reduced insulin resistance, Polycystic Ovarian Syndrome (PCOS): may help improve insulin levels and symptoms Fitness Enthusiasts: Fat utilization during prolonged low-moderate intensity exercise (body builders)

Who is a ketogenic diet not advisable for?

Under 18 without medical supervision, Immunocompromised, Individuals with a history of an eating disorder (could cause a spiral - extremely restrictive), Ppl with a history of poor discipline, Athletes who are relying on high-intensity effort for their sport

What dies is often better for weight loss?

Mediterranean diet with a focus on less sugar and a calorie reduction may be the most sustainable and effective approach for weight loss

Ketogenic diet & Sports performance?

Not a strategy to manipulate body weight - a longer-term approach is favoured with modified carbs - not zero, depends on the athlete - elite (need glucose) versus sub max (might work?, Depends on the event - Marathon (26km) versus ultra marathon (50k), Individual tolerance

Dietary fat recommendations for contribution of total energy intake?

should contribute 20-35% total energy intake (<10% from saturated fat)