Dietary Fats: Friend or Foe?

Rose Johnson7/19/15

IntroductionDietary fats are highly maligned nutrientsHealthy fats are important to long term

health

Goals & ObjectivesIncrease awareness of the role of healthy

dietary fats Understand fats in the blood Learn the difference between

LDL/HDL/TriglyceridesDescribe categories of fats Learn the sources of good dietary fatsUnderstand relationships between dietary

fats and chronic diseaseIdentify categories of unhealthy fats

Role of Dietary FatsThe body needs some fat from food. Dietary fats:

Provides a major source of energy Helps the body absorb some vitamins and

minerals. Helps to build cell membranes

Vital exterior of each cell, and the sheaths surrounding nerves.

Other Roles for Dietary FatsBlood clottingMuscle movementInflammatory response

A Few Words About CholesterolThe mix of fats and carbohydrates in the

blood is the biggest factor on levels of cholesterol and not the amount of cholesterol eaten from food.

While it is important to limit dietary cholesterol particularly for diabetics, it is not as big a problem as problematic as once believed.

Cholesterol is used by the body in the following ways:Estrogen/TestosteroneVitamin DOther compounds

A Few Words About CholesterolLDL cholesterol in the blood stream is what is

used to determine health risk.

Fats in the BloodLow Density Lipoproteins (LDL) - Bad

Carry cholesterol from the liver to other parts of the body

Excess LDL forms plaque on arterial wallsHigh Density Lipoproteins (HDL) - Good

Scavenge cholesterol from the blood and LDL and arterial walls and carries it back to the liver for disposal

TriglyceridesIs from fat eaten from food and transports fats to cellsFats are important for health but too much is

unhealthy

Categories of Dietary FatsGood fats

Monounsaturated fatsPolyunsaturated fats

Bad fatsInclude industrial-made trans fats. Saturated fats fall somewhere in the middle

Good FatsSources:

Vegetables, nuts, seeds, and fish. Healthy fats are liquid at room temperature,

not solid. Two categories of good/beneficial fats:

MonosaturatedPolyunsaturated

Good Fats: MonounsaturatedSources:

Olive oil, peanut oil, canola oil, avocados, and most nuts, as well as high-oleic safflower and sunflower oils.

Good Fats: PolyunsaturatedTwo main types of polyunsaturated fats:

Omega-3 fatty acids Omega-6 fatty acids

Good Fats: PolyunsaturatedOmega-3 fatty acids:

May help prevent heart disease/strokeHelps reduce blood pressure, raises HDL, &

lowers triglyceridesGood Sources of omega-3 fatty acids:

Fatty fish (salmon/mackerel,/sardines)Flaxseeds, walnuts, canola oil, and soybean oil.

Good Fats: PolyunsaturatedOmega-6 fatty acids:

Helps to protect against heart disease. Good Sources of omega-6 fatty acids:

Foods rich in linoleic acidVegetable oils such as un-hydrogenated

safflower, soybean, sunflower, walnut, and corn oils.

Bad Fats: Hydrogenated OilsDiets rich in bad fats are linked to:

Increases in bad cholesterol (LDL) levelsReduces good cholesterol (HDL) levelsContribute to inflammation related to:

Heart disease Stroke Diabetes/diabetes risk factors Other chronic conditions

Bad Fats: Hydrogenated OilsTrans-Fats

Listed as Partially Hydrogenated Oil (PHO) on food labelsBy-product of a process called hydrogenation

Turns healthy oils into solids Prevent rancidity.

Healthy oils become unhealthy when processed through hydrogenation

Bad Fats: Hydrogenated OilsResearch from multiple studies show that:

Trans fats can harm health in even small amounts

For every 2% of calories from trans fat consumed daily, the risk of heart disease rises by 23%.

Bad Fats: Hydrogenated OilsPermeate the food supply:

Commercial cookies and pastries to fast-food French fries

In our snack foodsRaw PHOs are abundant in supermarkets

Think: Shortening & conventional margarine products

In Between: Saturated FatsSolid at room temperature — think cooled

bacon grease.Common sources:

Red meat, whole milk and other whole-milk dairy foods, cheese, coconut oil, and many commercially prepared baked goods and other foods.

In Between: Saturated FatsDiets rich in saturated fats can:

Drive up total cholesterolIncrease more harmful LDL cholesterol, which

prompts blockages to form in arteries in the heart and elsewhere in the body.

Some health experts recommend limiting saturated fat to under 10% of calories daily

In Between: Saturated FatsExceptions

Tropical Oils Palm oil Coconut oil

Have been found to lower bad cholesterol levels (LDL)

Dietary Fat & DiseaseHeart Disease

Recent study of persons following a Mediterranean diet with extra-virgin olive oil or nuts, both rich sources of unsaturated fat, reduced the incidence of major cardiovascular events amongst patients with diabetes or other risk factors over a 4.8-year follow-up

Dietary Fat & DiseaseOther outcome from the study:

low-fat diets are losing credibility, and that incorporating healthy fats – such as those included in the Mediterranean diet – can improve heart health

Dietary Fat & DiseaseMediterranean diets including the following

guidelines were considered effective: High intake of olive oil, nuts, vegetables, fruits, and

mainly whole grain cereals– Moderate intake of fish and poultry– Low intake of dairy products, red meat, processed meats, and sweets– Wine in moderation, consumed with meals

Dietary Fat & DiseaseBreast cancer

Currently no clear evidence links any specific type of fat with cancer incidence

Colon cancerRecent & better studies contradict past studies

and revealed no significant association between fats and colon cancer

Dietary Fat & DiseaseProstate Cancer

Connection between prostate cancer and dietary fats is unclear

More research is needed to determine any connections between fats and prostate cancer

Dietary Fat & DiseaseOther chronic conditions

Preliminary findings do not offer sufficient evidence to suggest modifying dietary fat recommendations for conditions such as: Depression Osteoporosis Age-related memory loss Cognitive decline Macular degeneration

http://www.hsph.harvard.edu/nutritionsource/dietary-fat-and-disease/

Causes for ConfusionGuidance related to intake of dietary fats can

be confusing with some bodies research conflicting with others making it difficult to make good decisions about fats. Let’s examine a couple examples.

http://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good

Causes for ConfusionOne meta-analysis of 21 studies said that

there was not enough evidence to conclude that saturated fat increases the risk of heart disease, but that replacing saturated fat with polyunsaturated fat may indeed reduce risk of heart disease.

http://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good

Causes for ConfusionTwo other major studies narrowed the

prescription slightly, concluding that replacing saturated fat with polyunsaturated fats like vegetable oils or high-fiber carbohydrates is the best bet for reducing the risk of heart disease, but replacing saturated fat with highly processed carbohydrates could do the opposite.

http://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good

ConclusionWhere Do We Go From Here?

Focus on choosing foods with healthy fatsKeep portion sizes moderateDon’t fixate on fat percentages

http://www.hsph.harvard.edu/nutritionsource/healthy-fats/#tropical-oils

References:Harvard School of Public HealthThe Truth About Fats: The Good, The Bad, and The In-Betweenhttp://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good

Dietary Fat and Diseasehttp://www.hsph.harvard.edu/nutritionsource/dietary-fat-and-disease/

Cholesterolhttp://www.hsph.harvard.edu/nutritionsource/cholesterol/

Fats and Cholesterolhttp://www.hsph.harvard.edu/nutritionsource/fats-and-cholesterol-1/