Fat Facts: The Real Story On Cholesterol & Fats!

For the past two decades, low fat, low cholesterol is the mantra of those trying to lose weight, prevent cancer and avoid heart disease. In light of recent studies however, this view is outdated.
    3/16/2004 - For the past two decades, low fat, low cholesterol is the mantra of those trying to lose weight, prevent cancer and avoid heart disease. In light of recent studies however, this view is outdated.

Detailed research - particularly that done at Harvard - shows that the total amount of fat in the diet, whether high or low, has no real link with disease. Rather, what really matters is the type of fat in the diet. There are bad fats that increase the risk for certain diseases and good fats that lower the risk. The key is to substitute good fats for bad fats.

Furthermore, low fat diets do not offer an advantage in losing body fat, and in fact are often counterproductive as they cause an increase in muscle loss when compared to high-protein/moderate-fat diets like the Metabolic Diet. The Metabolic Diet and its two main derivatives, the Anabolic Solution and the Radical Diet, use a low-carbohydrate approach to optimize your body's anabolic and lipolytichormones to give you the body you want.

How about cholesterol? How bad it is depends on where it is. As it turns out, dietary cholesterolis bad for your heart but it is not the total villain in the picture. The bigger villain is blood cholesterol--the cholesterol circulating in your blood.

High blood cholesterol levels greatly increase the risk for heart disease. But surprisingly, the amount of cholesterol in food is not very strongly linked to cholesterol levels in the blood. What greatly affects blood cholesterol is the mix of fats in the diet.


Dietary Fats

Type of Fat Main Source State at Room Temperature Effect on Cholesterol Levels
Monounsaturated Olives; olive oil, canola oil, peanut oil; cashews, almonds, peanuts, and most other nuts; avocados Liquid Lowers LDL; raises HDL
Polyunsaturated Corn, soybean, safflower, and cottonseed oils; fish Liquid Lowers LDL; raises HDL
Saturated Whole milk, butter, cheese, and ice cream; red meat; chocolate; coconuts, coconut milk, and coconut oil Solid Raises both LDL and HDL
Trans Most margarines; vegetable shortening; partially hydrogenated vegetable oil; deep-fried chips; many fast foods; most commercial baked goods Solid or semi-solid Raises LDL

Too much cholesterol in the blood, though, can lead to problems. In the 1960s and 70s, scientists established a link between high blood cholesterol levels and heart disease. Deposits of cholesterol can build up inside arteries. These deposits, called plaque, can narrow an artery enough to slow or block blood flow. This narrowing process, called atherosclerosis, commonly occurs in arteries that nourish the heart (the coronary arteries).

When one or more sections of heart muscle fail to get the blood, and thus the oxygen and nutrients, they need, the result may be the chest pain known as angina. In addition, plaque can rupture, causing blood clots that may lead to heart attack, stroke, or sudden death. Fortunately, the buildup of cholesterol can be slowed, stopped, and possibly even reversed.

Cholesterol-carrying lipoproteins play a central role the development of atherosclerotic plaque and cardiovascular disease.

The two main types basically work in opposite directions:

Low-density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body. When there is too much LDL cholesterol in the blood, it can be deposited on the walls of the coronary arteries. Because of this, LDL cholesterol is often referred to as the 'bad' cholesterol.

High-density lipoproteins (HDL) carry cholesterol from the blood back to the liver, which processes the cholesterol for elimination from the body. HDL makes it less likely that excess cholesterol in the blood will be deposited in the coronary arteries, which is why HDL cholesterol is often referred to as the 'good' cholesterol.

When you have your cholesterol checked, the results will indicate your total blood cholesterol level. If you fasted overnight before giving a blood sample, the test results should also include separate counts or your HDL and LDL. In general, the higher your LDL and the lower your HDL, the greater your risk for atherosclerosis and heart disease.

For adults age 20 years or over, the most recent federal guidelines - From the National Cholesterol Education Program - Recommend the following target levels.

Recommended Target Levels:

  • Total cholesterol less than 200 milligrams per deciliter (mg/dl)
  • HDL cholesterol levels greater than 40 mg/dl
  • LDL cholesterol levels less than 100 mg/dl


Dietary Fat, Dietary Cholesterol & Blood Cholesterol

How much cholesterol you'll have in your blood will depend not so much on total fat you consume butthe type of fat you have had. Cholesterol in the diet contributes too but not as much as people supposed. Egg, for example, had proven to be not as bad as once thought in so far as heart fitness is concerned.

Moderate consumption like one a day does not increase heart disease risk in healthy individuals. While it's true that egg yolks have a lot of cholesterol and, therefore may slightly affect blood cholesterollevels, eggs also contain nutrients that may help lower the risk for heart disease, including protein, vitamins B12 and D, riboflavin, and folate.


The Villains: Bad Dietary Fats

Saturated Fats. Saturated fats are mainly animal fats. They are found in meat, seafood, whole-milk dairy products (cheese, milk, and ice cream), poultry skin, and egg yolks. Some plant foods are also high in saturated fats, including coconut and coconut oil, palm oil, and palm kernel oil. While saturated fats raise total blood cholesterol levels more than dietary cholesterol does, they tend to raise both the 'good' HDL and the 'bad' LDL cholesterol.

Trans Fats. Trans fatty acids are fats produced by heating liquid vegetable oils in the presence of hydrogen. This process is known as hydrogenation. The more hydrogenated an oil is, the harder it will be at room temperature. For example, a spreadable tub margarine is less hydrogenated and so has fewer trans fats than a stick margarine.

Most of the trans fats in the American diet are found in commercially prepared baked goods, margarines, snack foods, and processed foods. Commercially prepared fried foods, like French fries and onion rings, also contain a good deal of trans fat.

Trans fats are worse for cholesterol levels than saturated fats because they not only raise LDL (bad) cholesterol, but also lower HDL (good) cholesterol.


The Heroes: Good Dietary Fats

Unsaturated fats are found in products derived from plant sources, such as vegetable oils, nuts, and seeds. There are two main categories: polyunsaturated fats (which are found in high concentrations in sunflower, corn, and soybean oils) and monounsaturated fats (which are found in high concentrations in canola, peanut, and olive oils).

In studies in which polyunsaturated and monounsaturated fats were eaten in place of carbohydrates (in low-carb diets like the Metabolic Diet), these good fats decreased LDL levels and increased HDL levels.

Percentage of Specific Types of Fat in Common Oils and Fats*
Oils
Saturated
Mono-unsaturated
Poly-unsaturated
Trans
Canola
7
58
29
0
Safflower
9
12
74
0
Sunflower
10
20
66
0
Corn
13
24
60
0
Olive
13
72
8
0
Soybean
16
44
37
0
Peanut
17
49
32
0
Palm
50
37
10
0
Coconut
87
6
2
0
Cooking Fats
Shortening
22
29
29
18
Lard
39
44
11
1
Butter
60
26
5
5
Margarine/Spreads
70% Soybean Oil, Stick
18
2
29
23
67% Corn & Soybean Oil Spread, Tub
16
27
44
11
48% Soybean Oil Spread, Tub
17
24
49
8
60% Sunflower, Soybean, and Canola Oil Spread, Tub
18
22
54
5

* Values expressed as percent of total fat; data are from analyses at Harvard School of Public Health Lipid Laboratory and U.S.D.A. publications.


Dietary Fats & Heart Disease - Beyond The '30%' Recommendation

Many health agencies, including the American Dietetic Association, the American Diabetes Association, and the American Heart Association, recommend limiting fat intake to 30% or less of total daily calories as a means of preventing disease. However, there is no good evidence for any particular 'optimal' amount of total fat in a healthy diet.

The relation of fat intake to health is one of the areas that Harvard researchers have examined in detail over the last 20 years in two large studies. The Nurses' Health Study and the Health Professionals Follow-up Study have found no link between the overall percentage of calories from fat and any important health outcome, including cancer, heart disease, and weight gain.

What they have found to be important is the type of fat in the diet. There are clear links between the different types of dietary fats and heart disease. Logically, most of the influence that fat intake has on heart disease is due to its effect on blood cholesterol levels.

Of the bad fats - saturated and trans fats - trans fats are far worse when it comes to heart disease. The Nurses' Health Study found that replacing only 30 calories (7 grams) of carbohydrates every day with 30 calories (4 grams) of trans fats nearly doubled the risk for heart disease. Saturated fats increased risk as well, but not nearly as much.

For the good fats, there is consistent evidence that high intake of either monounsaturated or polyunsaturated fat lowers the risk for heart disease. In the Nurses' Health Study, Harvard researchers found that replacing 80 calories of carbohydrates with 80 calories of either polyunsaturated or monounsaturated fats lowered the risk for heart disease by about 30 to 40 percent.

Fish, an important source of the polyunsaturated fat known as omega-3, has received much attention in the past for its potential to lower heart disease risk. And there have been some studies to back this up, although not all have shown consistent benefits. One recent large trial, however, found that by getting 1 gram per day of omega-3 fatty acids over a 3.5 year period, patients who had previous suffered heart attacks could lower their risk of dying from heart disease by 25 percent.

(To get that amount of omega-3 fatty acids would require the equivalent of 1 daily serving of fatty fish, such as mackerel, salmon, sardines, or swordfish.) Although more research is needed, adding fish to the diet may help protect you from heart disease, and it doesn't have any known risks. The American Heart Association currently recommends that everyone eat at least two servings of fish a week.


Dietary Fat & Obesity

It is a common belief that the more fat you eat, the more body fat you put on, and the more weight you gain. This belief has been bolstered by much of the nutrition advice given to people over the past decade, which has focused on lowering total fat intake while increasing carbohydrate intake. However, current data show that this advice has been misguided. While total fat intake nationwide has dropped over the last decade, rates of obesity have increased steeply.

Most studies show that over the short term, a low-fat diet does result in weight loss. But many diets show such benefits over the short term. On the other hand, low-fat diets appear to offer no substantial advantages over diets with fat levels close to the national average.

Although more research is needed, a prudent recommendation for losing weight or maintain a healthy weight is to be mindful of the amount of food you eat in relation to the amount of calories you burn in a day. Exercising regularly is especially beneficial.


The Bottom Line - Recommendations For Fat Intake

Although the different types of fat have a varied - and admittedly confusing - effect on health and disease, the basic message is simple: limit the bad fats and replace them with good fats. Try to reduce both the trans and saturated fats in your diet as much as possible and replace them with polyunsaturated and monounsaturated fats.

The trickiest of these to attack are the trans fats. That's because they lurk in many different types of foods and aren't always included on the food label. But as awareness about trans fats increases, more 'trans-fat' free products are becoming available.

This is particularly so in Europe, but many items are also making their appearance in the North America, including trans-fat free margarine (which may also be labeled as 'non-hydrogenated' margarine). Such labeling of trans fat content has long been up to the food maker's discretion.

However, a report on trans fats from the Institute of Medicine concluding that there is no safe level of trans fats in the diet has finally prompted the (US) Food and Drug Administration to require that trans fats be listed as part of the Nutrition Facts food label. This decision came after several years of hearings, comments, and negotiations.

Until labels listing trans fats appear, which will probably take a year or more, it will take some detective work to determine if a food contains trans fats. Check the ingredient list for 'hydrogenated oils.' The higher up these are listed, the more trans fats the food contains.

Tips For Lowering Trans Fat Intake:

  • Choose liquid vegetable oils or a soft tub margarine that is contains little or no trans fats.

  • Reduce intake of commercially prepared baked goods, snack foods, and processed foods, including fast foods.

  • When foods containing hydrogenated or partially hydrogenated oils can't be avoided, choose products that list the hydrogenated oils near the end of the ingredient list.

Source:

http://www.hsph.harvard.edu/nutritionsource/fats.html

Be sure to also check out:
The Truth About Fast Foods!