For decades, the mantra for healthy eating has been “eat a low-fat, low-cholesterol diet.” Touted as a way to lose weight and prevent heart disease and other chronic conditions, millions of people have followed this advice. Seeing a tremendous marketing opportunity, food companies re-engineered thousands of foods to be low-fat or fat-free. The low-fat approach to eating may have made a difference for the occasional individual, but as a nation, it has nether helped us control our weight nor become healthier. In the 1960s, fats and oils supplied Americans with about 45 percent of their calories. About 13 percent of the population was obese and less than one percent had type 2 diabetes. Today, Americans take in less fat, getting about 33 percent of calories from fats and oils; yet 34 percent of the population is obese, and eight percent has diabetes (mostly type 2). (Source: Harvard School of Public Health).
Research has shown that the total amount of fat in your diet isn’t linked with weight or disease. What actually matters is the type of fat in your diet. Trans fats and saturated fats increase your risk of cardiovascular disease, while monounsaturated and polyunsaturated fats do just the opposite. But then you ask, “what about cholesterol in food?” The answer is, for most people the mix of fats in their diets influences cholesterol in their bloodstreams far more than cholesterol in food.
Almost all foods contain some fat. Even foods like carrots and lettuce contain small amounts of fat. That’s a testament to how important fats are for your health and well-being. Fat provides a terrific source of energy for your body as well as a great depot for storing it. It is an important part of cell membranes, helping govern what gets into and out of your cells. Your body uses cholesterol as the starting point to make estrogen, testosterone, vitamin D, and other vital compounds. Fats are also biologically active molecules that can influence how your muscles respond to insulin. Also, different types of fats can fire-up or cool down inflammation in your body.
Your body packages fat and cholesterol into tiny protein-covered particles called lipoproteins in order to get them into your blood stream. Some of these lipoproteins are big and fluffy, and others are small and dense. However, the most important ones to remember for your health and well-being are low-density lipoproteins, high-density lipoproteins, and triglycerides as explained below.
Low-density lipoproteins (LDL) carry cholesterol from your liver to the rest of your body. Your cells latch onto these particles and extract fat and cholesterol from them. When there is too much LDL cholesterol in your blood, these particles can form deposits in the walls of your coronary arteries and other arteries throughout your body. These deposits, called plaque can cause your arteries to narrow and limit blood flow, resulting in a heart attack or stroke. Thus, LDL cholesterol is called your bad cholesterol.
High-density lipoproteins (HDL) scavenge cholesterol from your bloodstream, your LDL, and your artery walls and ferry it back to your liver for disposal. Thus, HDL cholesterol is referred to as your good cholesterol.
Triglycerides comprise most of the fat that you eat and that travels through your bloodstream. Because triglycerides are your body’s main vehicle for transporting fats to your cells, they are essential for good health. However, an excess of triglycerides can be unhealthy.
The type of fat in your diet determines to a large extent the amount of total and LDL cholesterol in your bloodstream. Cholesterol in food matters too, but not nearly as much. You can basically break the fats in your diet into three categories; good, bad, and very bad.
Good Fats
Unsaturated fats are called good fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles.
Unsaturated fats are predominantly found in foods derived from plants, such as vegetable oils, nuts, and seeds. They are liquid at room temperature.
Furthermore, there are two types of unsaturated fats: monounsaturated and polyunsaturated. Monounsaturated fats are found in high concentrations in canola, peanut, and olive oil, in avocados, nuts like almonds, hazelnuts, and pecans, and seeds such as pumpkin and sesame. Polyunsaturated fats are found in high concentrations in sunflower, corn, soybean and flaxseed oil. They also are found in foods such as walnuts, flaxseeds and fish.
Research has shown that replacing carbohydrates in your diet with good fats reduces harmful levels of LDL and increases protective HDL in your bloodstream. A randomized trial called the Optimal Macronutrient Intake Trial for Heart Health showed that replacing a carbohydrate-rich diet with one rich in unsaturated fat - predominantly monounsaturated fats - lowers blood pressure, improves lipid levels, and reduces the estimated cardiovascular risk.
Bad Fats
Saturated fats are called bad fats because they increase your total cholesterol level by elevating harmful LDL. Your body can produce all the saturated fat that it needs, so you don’t have to get any from your diet. In the US and other developed countries, saturated fats come mainly from meat, seafood, poultry with skin, and whole-milk dairy products. A few plant sources, such as coconuts and coconut oil, palm oil and palm kernel oil, also are high in saturated fats.
As general rule it’s good to keep your intake of saturated fats as low as possible. Saturated fats are found in many foods, including vegetable oils that are mainly unsaturated fats, so you can’t completely eliminate them from your diet. Because red meat and dairy fat are the main sources of saturated fats for most people, minimizing them in your diet is the primary way to reduce your intake of saturated fat.
Very Bad Fats
Trans fatty acids, more commonly known as trans fats, are made by heating liquid vegetable oils in the presence of hydrogen gas, - a process called hydrogenation. Partially hydrogenating vegetable oils makes them more stable and less likely to spoil. It also converts the oil into a solid which makes transportation easier. Partially hydrogenated oils can also withstand repeated heating without breaking down, making them ideal for frying fast foods. This is reason partially hydrogenated oils have been a mainstay in restaurants and the food industry.
Trans fats are worse for cholesterol levels than saturated fats because they raise bad LDL and lower good HDL. They also increase inflammation, an over-activity of the immune system that is associated with heart disease, stroke, diabetes, and other chronic conditions. Even small amounts of trans fats in your diet can have harmful health effects. For every extra two percent of daily calories from trans fat (the amount in a medium order of fast food French fries) the risk of coronary heart disease increases by 23 percent. It is estimated that eliminating trans fats from the US food supply would prevent between six and 19 percent of heart attacks and heart attack-related deaths (more than 200,000) each year.
Recommendations for Fat in Your Diet
Are you confused at this point about the type of fats and their varied effects on your health? If so remember the basic message to replace the bad fats in your diet with the good fats. Here are some suggestions to help you limit the bad fats in your diet.
- Eliminate trans fats from partially hydrogenated oils. Check food labels for the presence of trans fats and avoid fried fast foods.
- Limit your intake of saturated fats by cutting back on red meat and full-fat dairy products. When possible replace red meat with poultry, fish, beans, and nuts. Also, try switching from whole milk and other full-fat dairy foods to lower-fat versions.
- Use liquid vegetable oils rich in polyunsaturated and monounsaturated fats in place of butter in your cooking and at the table.
- Eat one or more sources of omega-3 fats every day. Excellent sources are fish, walnuts, canola or soybean oil, ground flax seeds and flax seed oil.
