The Facts on Fats
Your user's guide to the lipids in your life

Lisa Goldman

Dietary fat. Drop this phrase into conversation and people glance away guiltily or giggle nervously, thinking of their poor coronary arteries. We know we eat too much fat, but we also know we have to have some fat in our diets. So how much is enough? How much is too much? And what kinds of fat should we eat?

Having said that our bodies need some fat, we hasten to add that they need less than many of us eat — and far less of the types we love to overindulge in. “Fat adds flavour and texture to foods,” says Heather McColl, a registered dietitian in Vancouver, “but this doesn’t mean eating a lot of greasy burgers and potato chips. Instead, we need fat from quality sources such as fatty fish, peanut butter and lean protein foods.”

About 25% to 30% of our daily caloric intake should come from fat, which translates to about 65 grams of fat or less for women and 90 grams or less for men. But which fats should we enjoy — and in what proportions — and which should we avoid?

Healthy fats are crucial to us. Too much fat, especially of the dangerous types, can contribute to weight gain and obesity, heart disease, diabetes, cancer, sleep apnea, gallstones and osteoarthritis “If we can lower our bad and ugly fats and replace them with the good types, we’ll be healthier,” says Dr. Bruce Holub, a leading lipid researcher and a professor emeritus of nutritional sciences at the University of Guelph in Ontario. Read on to find out how. 

The good

Unsaturated fats (monounsaturated and polyunsaturated fats) should be a staple part of your diet. These fats give us energy. They help regulate our heart rate, blood pressure and central nervous system and carry the fat-soluble vitamins (A, D, E and K). They also protect vital organs such as the liver and kidneys and help maintain healthy skin and hair. These fats can lower your risk of heart disease by reducing “bad” blood cholesterol and raising “good” cholesterol (see “Cholesterol,” below).

Monounsaturated and polyunsaturated fats are found in vegetable oils (olive, peanut, canola, safflower), as well as in avocados, nuts and seeds. Most vegetable oils (and animal fats) contain a mix of different fats, but are referred to as saturated, monounsaturated or polyunsaturated depending on which fat is dominant. The fat composition of your extra-virgin olive oil, for example, is 13% saturated, 72% monounsaturated and 8% polyunsaturated, so this oil is considered a monounsaturate. Some experts recommend a fat balance of 37% monounsaturated, 33% polyunsaturated and 30% saturated.

Other polyunsaturates are the omega-3 fatty acids. These lipids abound in fish, especially deep-coloured fatty varieties such as anchovies, sardines, salmon and herring. They also occur, in lesser quality, in plant foods such as English walnuts, flaxseed and corn oil. Omega-3s cut inflammation, lower “bad” cholesterol, raise “good” cholesterol and decrease the risk of blood clots.

“Omega-3s are the No. 1 added ingredient in the food industry right now. Fish oil is being added to yogourt and milk,” says Holub. A good thing, since the average Canadian consumes only one serving of fish every 10 days, which won’t supply the one to three grams of omega-3s recommended per day. (That would require two to three servings of fatty fish per week.) “There’s now an appreciation that even a minor consumption of omega-3s has profound health benefits, especially for the brain and the cardiovascular system. It’s good for you, both above and below the neck,” says Holub.

The bad

Too much saturated fat is a major culprit when it comes to lipids that do more harm than good, but we do need a small amount in our diets. Specifically, we need this fat to give us energy, aid in hormone and cell-membrane production and help boost the immune system. These lipids are crucial for developing babies — breast milk has plenty. Usually solid at room temperature, these fats occur in whole milk, cream, butter, cheese, lard, red meat and processed meats such as hot dogs and salami. They’re also plentiful in tropical oils such as coconut and palm, but even soybean oil is 16% saturated fat. Eaten in excess, saturated fats can push blood cholesterol levels too high — particularly levels of “bad” cholesterol.

How saturated can a fat get? Well, coconut oil tops the list at 87%, while butter is 60% saturated, palm oil 50% and lard 39%. One tablespoon of oil or solid fat contains about 14 grams of fat and about 125 calories.

The recommendation is to keep saturated fat to no more than 10% of total calories. “Those with high blood cholesterol levels are advised to keep saturated fat to 7% or less of total calories,” McColl says. Trans fats (see “The Ugly,” below) should be kept to under two grams a day.

The ugly

Trans fats are modern abominations made by incorporating hydrogen into heated vegetable oils to render them more stable and increase their shelf life. They’re found in hard margarine, shortening, commercial baked goods, candy bars and deep-fried restaurant foods such as french fries and onion rings, as well as snacks and convenience foods. They promote the buildup of cholesterol-rich deposits on artery walls and raise “bad” cholesterol while lowering the “good.”

“These are now regarded as many times worse than saturated fats in the promotion of heart disease,” Holub says. They’re so harmful that countries such as Denmark and cities such as New York have moved for bans on trans fats in products and fast food. The Canadian government has a task force in place to reduce trans fats, but has yet to ban them.

Cholesterol

“Cholesterol is a soft, waxy substance that is present in every cell of the body. We need it to make hormones, cells, vitamin D and the bile acids that help digest fat,” says McColl. Most Canadians can safely consume 300 milligrams of dietary cholesterol a day, but bear in mind that one large egg has about 211 milligrams and two strips of bacon 35, so it adds up fast. “If you have high blood cholesterol or are at risk for heart disease, the recommendation is to keep consumption down to less than 200 milligrams a day,” says McColl.

But the body can’t function without some cholesterol. Too-low levels have been linked to depression, accidents, suicide and violent behaviour.

LDL and HDL

Cholesterol is not soluble in blood and must therefore be be transported in part-fat/part-protein vehicles called lipoproteins. LDL cholesterol is so called because it’s
carried from the liver to various parts of the body by low-density lipoproteins (LDL). When there’s too much LDL cholesterol in the blood, it can be deposited on the walls of the coronary arteries and lead to blockages and heart disease — hence it’s bad connotation. “Good” cholesterol is the same waxy substances as “bad,” but it’s transported by high-density lipoproteins (HDL), which have the ability to pick up excess cholesterol and return it to the liver to be processed for elimination.

Each day your hard-working liver manufactures about 1,000 milligrams of cholesterol to carry out critical internal repairs and maintenance. This represents about 80% of the cholesterol in the body; the rest is absorbed from food. Too much dietary cholesterol from foods such as egg yolks, shrimp, liver and butter can elevate blood cholesterol levels, but not as much as an excess of saturated and trans fats can, Holub says.

Triglycerides

Triglycerides are the other major form of fat in the blood along with cholesterol. They consist of three molecules of fatty acids attached to an alcohol molecule called glycol. Triglycerides rise after we eat fat or drink alcohol. They can be elevated in diabetes and at very high  levels, cause inflammation of the pancreas.

In a nutshell, Holub recommends that we reduce our intake of saturated and trans fats, increase our intake of omega-3 fatty acids and maintain a balanced intake of monounsaturated and polyunsaturated fats. Always check the Nutrition Facts on product labels for total fat, saturated fat, trans fat and cholesterol.

All types of fat deliver nine calories per gram — more than twice the four grams of energy in a gram of protein or carbohydrate and two more than a gram of alcohol’s seven calories

It’s all in a day

How fast the fat adds up!

Breakfast

1 cup Muesli
            4 g (1 g saturated, 0 g trans), 0 mg cholesterol
1⁄2 cup 2% milk
            2.5 g (1.4 g saturated, 0 g trans)
            10 mg cholesterol
coffee with 2 tbsp half-and-half cream
            4 g (2 g saturated, 0 g trans), 11 mg cholesterol
1 poached egg
            5 g (2 g saturated, 0 g trans), 211 mg cholesterol
1 slice whole wheat toast
            1 g (0 g saturated, 0 g trans), 0 mg cholesterol
1 tbsp butter
            12 g (7 g saturated, 0 trans), 30 mg cholesterol

TOTAL: 28.5 g (13.4 g saturated), 262 mg cholesterol

Morning snack

blueberry muffin
TOTAL: 11 g (1.5 g saturated, 0.1 g trans), 5 mg cholesterol

Lunch

1 roast beef sandwich
            14 g (4 g saturated, 0 g trans), 51 mg cholesterol
1 tbsp regular mayonnaise
            11 g (1.5 g saturated, 0 g trans), 5 mg cholesterol
1 small serving French fries
            13 g (2.5 g saturated, 0.4 g trans), 0 mg cholesterol

TOTAL: 38 g (8 g saturated), 56 mg cholesterol

Afternoon snack

3⁄4 CUP low-fat yogourt

TOTAL: 3 g (1.5 g saturated, 0 g trans), 15 mg cholesterol

Dinner

1 cup macaroni and cheese
            17 g (7 g saturated, 0 g trans), 13 mg cholesterol
1 serving frozen meat loaf
            11 g (4.5 g saturated, 0.2 g trans), 72 mg cholesterol
1 cup romaine Lettuce with 1 tbsp Italian dressing
            3.5 g (0.5 g saturated, 0 g trans), 0 mg cholesterol
1 slice apple pie
            14 g (5 g saturated, 0 g trans), 0 mg cholesterol

TOTAL: 45.5 g (17 g saturated,g trans), 85 mg cholesterol

TOTAL fat FOR THE DAY
126 g (41.4 g saturated, 0.7 g trans), 423 mg cholesterol

To get into the recommended 65-gram zone, this woman needs to cut her daily fat intake by almost half. Good places to start? Skip the coffee cream and spread jam instead of butter on her toast. Substitute fresh fruit for the muffin and vegetable soup for the fries. A tomato-sauce pasta would be much lower in fat than mac and cheese, and she could toss the apple pie in favour of an apple. She would also be well advised to replace one of the servings of beef with an omega-3-rich fillet of fish. These steps will also help bring her saturated fat intake closer to the recommended 10-gram limit. Forgoing the egg at breakfast would bring her cholesterol down below 300 milligrams.