This is the second monthly newsletter, and like the first, it deals with nutrition - specifically the different types of fat in our diet. However, the newsletters will deal with a wide range of topics, including disease prevention, physical activity, aging well and many other subjects. You can contact me at firstname.lastname@example.org. I welcome your comments and suggestions!
For many years, researchers focused on the total amount of fat in the diet, but now it's clear that the type of fat we eat is more important to heart health, and many other aspects of our health, than just the overall amount.
Every living cell in the body needs essential fatty acids (polyunsaturated fats). They are essential for rebuilding and producing new cells. They are also necessary for the production and balance of prostaglandins, hormone-like substances, which regulate all body systems and functions, including the cardiovascular, immune, reproductive, and central nervous systems. Essential fatty acids are found in high amounts in the brain where they assist in the transmission of nerve impulses; they are necessary for normal brain function. Japanese researchers have verified that a deficiency of essential fatty acids can result in an impaired ability to learn and recall information.
Fats -The different types
Fats are named according to their chemical structure, which determines how they affect our health (see box). The basic types in our diet are:
- saturated fat
- trans fatty acids, or partially hydrogenated fats/oils
- monounsaturated fats
- polyunsaturated fats which include
- omega-3 fatty acids - ALA (alpha linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)
- omega-6 - linoleic acid.
The body can make some of the fats it needs, but the two polyunsaturated fats, omega-3 and omega-6 are "essential" - meaning that they have to come from our diet.
To better understand why omega-3 fatty acids are so vital to health, let's focus on each individual fatty acid and its function. EPA, plays a critical role in cell membranes and in other body functions and structures. DHA is found in high concentration in the grey matter of the brain and the retina of the eyes, and is instrumental in the function of brain cell membranes, which are important for the transmission of brain signals.
Minimize your consumption of saturated fat
It's been clear for quite some time that our saturated fat intake should be low - a maximum of 10% of our daily calories, including trans fats (see below). Saturated fat is found in animal foods such as beef, pork and lamb as well as full-fat dairy products like whole milk and cheese. It is the main dietary contributor to elevated LDL (low density lipoprotein) cholesterol, the "bad" kind, which increases the risk of heart disease, and other health problems.
Try to avoid trans fats entirely
Even worse for our health are trans fatty (or "partially hydrogenated") acids. The advantages of these fats for manufacturers and restaurants are their long shelf life, "buttery" taste and texture, and stability for deep frying. But even at 1 - 3% of total calorie consumption, trans fats can significantly increase the risk of heart disease.
Monounsaturated fats are beneficial
Monounsaturated fatty acids such as olive and canola oil, are effective in lowering LDL cholesterol. The oleic acid found, for example, in olive oil, reduces blood pressure.
Essential fatty acids are anti-inflammatory in nature, and researchers think that they could have a beneficial effect on diseases which are low-grade systemic inflammatory conditions, such as heart disease, stroke, diabetes mellitus, hypertension and cancer, psoriasis, eczema and rheumatoid arthritis.
Omega-3 fatty acids - EPA and DHA, the super stars
EPA and DHA probably have numerous health benefits - some are clear, other evidence is preliminary.
- They lower the risk of heart disease, including heart attacks and arrhythmias (if consumption is started before the arrhythmia exists).
- There is some evidence that fish (and EPA and DHA) consumption may slow the rate of cognitive decline in early Alzheimer's disease. While it's not certain that this is a cause and effect relationship, it makes sense because DHA found in high concentration in the grey matter of the brain.
- Consuming fish (and EPA and DHA) also may reduce the risk of colorectal cancer - the 3rd leading cancer in both men and women in Canada and the US.
- There is preliminary evidence that eating fish (and EPA and DHA) may reduce the risk of some eye diseases, by reducing inflammation, including macular degeneration (which is the leading cause of blindness in older people); however, it's too soon to recommend EPA and DHA for this reason.
Omega-6 fats are essential, but in moderation
Many researchers believe that before industrialization, about 200 years ago, we used to eat equal amounts of omega-6 and omega-3 fats. However, now, we tend to eat far more omega-6 fats since they are readily available in vegetable oils. There is some evidence that this imbalance increases the risk of some cancers - at least in mice.
About 30% of our calories should come from fat, but saturated fat and trans fatty acids combined should make up no more than 10% of our calories. However, do keep in mind that trans fats should be avoided as completely as possible. At the opposite extreme, diets with less than 20% of calories from fat tend to be high in carbohydrates which can raise triglyceride levels and keep down HDL (high density lipoprotein) cholesterol - both risks for heart disease.
Salmon is the best source of EPA and DHA; other fish that contain good amounts include rainbow trout, sardines, flounder, sole and tuna. Two servings a week is recommended. Fish-oil pills are a reasonably good substitute for fish. If you're a vegetarian, look for food or supplements with DHA from algal oil.
Finally, keep in mind that omega-6 fats are essential - we need them in our diet - but the balance between them and omega-3s is important.
To understand the different types of fats, it helps to think of them as being like Tinkertoys. Like all organic compounds, they are based on carbon.
- Most carbon atoms in fat molecules are connected to hydrogen atoms; when all the carbon atoms are bonded to hydrogen, a fat is "saturated."
- Trans fatty acids are created when hydrogen is added to the molecules of an ordinary liquid vegetable oil. This process makes these "partially hydrogenated" fats solid or semisolid at room temperature, for example in some margarines and the fats used in many commercial baked goods and restaurant deep-frying.
- If one ("mono") carbon is instead hooked to a fellow carbon atom, that's "monounsaturated"; canola oil and olive oil, for example, are high in monounsaturated fats.
- If several ("poly") carbon atoms are bonded to carbon instead of hydrogen, the fat is "polyunsaturated" - like the main ingredients in soybean or corn oil and fish oil.
- Polyunsaturated fatty acids come in two varieties, named for where their first unsaturated (carbon-carbon) bond appears in their long Tinkertoy-like chains. Chemists count from the end of the chain - hence "omega" - the end of the Greek alphabet - so polyunsaturated fats are either omega-3 or omega-6.
- Omega-3 fatty acids include EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid), both found in fish, and ALA (alpha linolenic acid) found, for example, in leafy green vegetables, nuts, soy oil and flaxseed.2
- Omega-6 - LA (linoleic acid) - is readily available in vegetable oils.
The suggestions and recommendations in this newsletter are not intended to be prescriptive or diagnostic. The information is accurate and up to date to our knowledge, but we are not responsible for any errors in our sources of information.
1. Strong hearts: unraveling the latest research. Tufts University Health & Nutrition Letter 2005;23(3):S1-4.
2. Studies find new omega-3 benefits. But are you getting the right healthy fats? Tufts University Health & Nutrition News Letter 2007;25(5):4-5.
3. Mozaffarian D, Katan MB, Ascherio A et al. Trans fatty acids and cardiovascular disease. N Engl J Med 2006;354:1601-1613.
4. McDonald B. Monounsaturated fatty acids and heart health. CMAJ 1991;145:473.
5. Terés S, Barceló-Coblijn G, Benet M et al. Oleic acid content is responsible for the reduction in blood pressure induced by
olive oil. PNAS 2008;105:13811-13816.
6. Das UN. Can essential fatty acids reduce the burden of disease(s)? Lipids Health Dis 2008;7:9 doi:10.1186/1476-511X-7-9.
7. Liebman B. Omega medicine? Is fish oil good for what ails you? Nutrition Action Health Letter 2007;34(8):3-6.
8. Fish, omega-3s show promise as early dementia defense. Tufts Health & Nutrition Letter 2008;25(11):1-2.
9. Consuming fish and omega-3s reduces risk of colorectal cancer. Tufts Health & Nutrition Letter 2008;26(6):1-2.
10. Colorectal cancer facts and figures. Public Health Agency of Canada 2009;
11. Are fish-oil pills as good as eating fish for omega-3s? Tufts University Health & Nutrition Letter 2008;27(1):6.
These newsletters will help you make better choices for better health. The choices that you make today can either have a positive or negative impact on your overall health. Begin by choosing better. It is a step toward longevity.
Ramilas Healing Arts Clinic