Study Notes on Dietary Fat and Health

High intakes of saturated and trans fats increase the risk of heart and artery disease.
High fat intakes are also linked with a higher risk of developing some types of cancer.
Obesity is connected to the overconsumption of high-energy density, fatty foods.
Examples of high-fat foods include butter, margarine, potato chips, other fried snacks, and donuts, all of which can contribute to chronic diseases.

A table captures recommendations for dietary fat intake for healthy adults:
- Saturated Fat Intake: Less than or equal to 10% of total calorie intake per day (DRI).
- Trans Fat Intake: Limit to less than or equal to 1% of total calories per day (WHO).
- Linoleic Acid Intake: 5 to 10% of total calories per day (DRI); WHO recommends 0.6 to 1.2% of total calories.
- Cholesterol Intake: As low as possible while ensuring adequate total energy intake (DRI).
These recommendations are informed by scientific evidence linking fat, saturated fat, trans fats, polyunsaturated fats, and cholesterol with chronic disease risk.

The AMDR provides general guidelines:
- Total Fat Intake: Should be between 20 to 35% of total daily energy intake.
By adhering to the AMDR, one is likely to meet recommendations for saturated fat, trans fat, and cholesterol.
Suggestions for healthy oils include those high in polyunsaturated fatty acids, such as sunflower and canola, and to eat fish regularly to meet polyunsaturated fatty acid recommendations.

Lipoproteins are responsible for transporting fat in the bloodstream:
- Chylomicrons: Carry lipids from the intestines to the liver.
- Very Low-Density Lipoproteins (VLDL): Carry triglycerides and lipids from the liver to body cells.
- Low-Density Lipoproteins (LDL): Transport cholesterol and lipids to tissues. Formed from VLDLs after donating triglycerides.
- High-Density Lipoproteins (HDL): Carry cholesterol away from tissues to the liver for disposal.
LDL and HDL levels are both significant risk factors for heart disease.

Composition and density of lipoproteins are critical to their health implications:
- LDL Composition: High in lipids (about 80% lipid to 20% protein) and especially high in cholesterol. Elevated LDL levels correlate with higher cardiovascular disease (CVD) risk. Often referred to as "bad cholesterol"—this terminology can be misleading.
- HDL Composition: Higher in protein (approximately equal parts lipid and protein) and lower in cholesterol compared to LDL. Higher HDL levels are correlated with lower CVD risk, often labeled as "good cholesterol"—again, this label can be misleading as both are essentially the same compound but in different proportions.

There is a significant distinction between dietary cholesterol and blood cholesterol:
- Foods like eggs, beef, poultry, cheese, and milk contain cholesterol, while plant foods do not.
- Blood cholesterol levels are influenced more significantly by saturated and trans fats than by dietary cholesterol itself.
- The body regulates blood cholesterol: high dietary cholesterol may lead to a reduction in internal cholesterol production, depending on an individual’s genetics.

Recommendations to manage cholesterol levels include:
- Limit intake of saturated and trans fats. Aim for saturated fat intake of 5% to 6% of calorie intake and trans fats below 1%.
- Increase the consumption of vegetables, fruits, whole grains, and nuts to decrease the intake of high-fat foods.
- Regular physical activity is effective in raising HDL levels; however, there are no specific dietary measures proven to effectively raise HDL.
Foods high in dietary cholesterol can still be part of a balanced diet without negatively impacting blood cholesterol, especially if lower fat options are chosen.

Two essential polyunsaturated fatty acids:
- Linoleic Acid: 18 carbon omega-6 fatty acid.
- Linolenic Acid: 18 carbon omega-3 fatty acid.
These fatty acids are vital as they cannot be synthesized by the body and serve numerous essential functions, including:
- Providing raw materials for eicosanoids (regulatory compounds for various body functions).
- Forming parts of cell membranes and are necessary for brain and nervous system health.
- Supporting growth, vision, and immune functions.

Omega-3 Fatty Acids: Sourced from fatty fish (mackerel, salmon, anchovies, herring, sardines, tuna), recommended intake is 350 to 425 grams of fish each week.
Omega-6 Fatty Acids: Found in seeds, nuts, vegetable oils (corn, soybean, safflower, sunflower), and cold-water fish.
Nutritional products such as omega-three eggs are also available, produced from hens fed omega-three fatty acids.

Fish oil supplements are generally not recommended due to potential risks:
- They may contain high levels of vitamins, such as vitamin A, posing a risk to pregnant women.
- They could raise LDL cholesterol levels and affect bleeding times.
- Possible contaminants from fish livers and skins include heavy metals and toxins.

Trans fats are created through hydrogenation and are commonly found in partially hydrogenated oils, mainly from processed foods.
Health risks associated with trans fats include:
- Raising LDL cholesterol and lowering HDL cholesterol.
- Causing inflammation in the body.
Trans fats were banned in Canada in 2020 due to their negative impacts on heart health.

Five actions for utilizing healthier oils:
- Choose unsaturated oils like canola and olive oil; these can replace saturated fats in cooking.
- Stock nonstick cookware and consider using an oil sprayer to minimize oil usage in dishes.
- Select fresh ingredients over processed snacks to reduce overall fat intake.

Follow the AMDR for fat: 20% to 35% of total energy intake.
Select foods with lower saturated fat and higher polyunsaturated fat content.
Include fatty fish and nuts for omega-3 and omega-6 fats.
Limit added fats in cooking and condiments.
Choose low-fat meats and dairy products for health benefits without raising blood cholesterol levels.