GOOD FATS, BAD FATS

Always remember that with fats, oils really ain't oils. But which are the good ones and why? Which are the bad ones and why? How do I know?... Read on….

WHAT ARE FATTY ACIDS?

Essential fatty acids (EFA's), or 'good' fats, are necessary for mammalian life. They should never be confused with the saturated (or 'bad') fats. Saturated fats are those found in milk, cream, butter, red meats, cheese and margarine (which contain trans fat or 'hydrogenated' oils). These 'bad' fats are the ones associated with chronic diseases, such as diabetes, and contribute to the hardening of arteries, raising blood pressure and increasing body fat.

Essential fatty acids, on the other hand, are required by our bodies for reproduction, healthy skin and hair, wound healing,and the health of our brain, eyes and many other glands, tissues and functions. They also help to lower blood triglycerides (body's storage form of fats), lower blood cholesterol, reduce platelet aggregation (a process of blood cells clumping together), provide the body with energy and burn fats. They also provide components for nerve cells, cell membranes and prostaglandins (hormone like structures). Prostaglandins play a vital role in the regulation of tissue function, cell signalling (or 'communication'), gene transcription (process by which DNA is copied); and act as natural anti-inflammatories in conditions such as arthritis, colitis and other inflammatory disorders. EFA's help to protect the body against heart disease, cancer and many other chronic diseases. EFA's are also required for the proper assimilation of the fat-soluble vitamins A, D, E and K. To absorb (and provide) such vitamins, the body requires at least 25g of 'good' fat per day.

They are termed 'essential' as your body cannot make them. They must be ingested through our diet.

There are two basic categories of EFA's: Omega-3 and Omega-6. Both of these we cannot live without.
  • Omega-6 EFA's include linoleic (LA) and gamma-linolenic acids (GLA); found in raw nuts, seeds, legumes and sesame and soybean oil. Omega-6 EFA's also include arachidonic acid (A A) and dihomogamma linolenic acid (DGLA)
  • Omega-3 EFA's include alpha-linolenic (ALA) and eicosapentaenoic acid (EPA); found in fresh deepwater fish, fish oils, certain vegetable oils (eg: canola, walnut, soybean and flaxseed). Omega-3 EFA's also include docosahexanoic acid (DHA)

TYPES OF FATS

Saturated fats are found in most animal products and processed foods. They are also found in some vegetable fats such as cocoa butter, coconut and palm oil. They pack on excess weight and shoot up blood cholesterol and are often indicated in chronic diseases such as heart disease and cancer.

Polyunsaturated fats are found in some vegetable oils. They lower HDL (or the 'good' cholesterol) as well as LDL ('bad') cholesterol and oxidise more rapidly, so have an increased need for antioxidants (eg: vitamin E) to keep them from becoming rancid. These are generally more unstable than the monounsaturates, especially at high temperatures so are not as useful for cooking.

Monounsaturated fats lower cholesterol, but leave HDL's alone. They are found in peanut and olive oils and avocados. They contain a diverse range of natural antioxidants to help guard against oxidation. They are generally safer than the polyunsaturates to use when cooking, as they are more stable at higher temperatures.

Trans-monounsaturated fatty acids are found in fairly low levels in the fats of ruminant animals such as cattle, sheep and goats. They are also found as hydrogenated oils in margarine.

Always ensure you are ingesting sufficient fat-soluble antioxidants (eg: vitamin E) to prevent your body's cells from free radical damage (eg: saturated fat oxidation).

Fatty acids are either saturated (solid at room temperature) or unsaturated (liquid at room temp). EFA's are all unsaturated.

So what about dairy? Dairy sources do provide the fat-soluble vitamins, but they also contain saturated fats. Thus, it is wise to limit these to a maximum of 10g/day and to utilise other sources.

Easy ways to incorporate more EFA's, and less of the saturated or unwanted fats into your diet include:
  • Limiting your intake of animal products
  • Increasing nuts, seeds, legumes and dark green leafy vegies
  • Choosing fish and skinless poultry
  • Lean cuts rather than fat laden meats.
In our diet, they are needed in proportion with one another - taking any one of them in isolation can lead to deficiences of the other/s. The recommended ratio of omega-6: omega-3 is 4:1.

OMEGA-3 FATTY ACIDS

Omega-3 fatty acids convert to EPA and DHA, both of which are found in abundance in many body tissues including the adrenal and sex glands, the retina and the brain. In the body, both EPA and DHA can be manufactured from LNA (omega-3), which is found in abundance in flax and hemp seeds. Other good sources include dark green leafy vegies, pumpkin seeds, soy, canola (rape), and walnut oils.

This conversion requires the presence of an enzyme, delta-6-desaturase. Factors that slow down this conversion include trans fatty acids and saturated fats, cholesterol and/or diets high in sugar and processed foods. Their conversion happens in the liver, so those with under-functioning livers, may also be at risk of deficiency. People low in this enzyme should supplement EPA/DHA into their diet.

In the diet, both EPA and DHA can be gained from eating cold-water fatty fish (eg: salmon, sardines, trout, mackeral, eel). EPA and DHA help to keep saturated fats and cholesterol dispersed.

When cooking fish, it is best to eat it raw, or to lightly grill or steam it with the skin intact, as the beneficial oils are located just under the skin.

Fresh and wild fish is generally superior in quality compared with farmed fish. Farmed fish are generally lower in vitamins A and D, and in LNA (omega-3) content. This is due to a more varied diet of the wild fish; whereas many farmed fish are 'fed' food that is often lacking in variety and/or nutritional value.

OMEGA-6 FATTY ACIDS

Good sources include evening primrose oil (EPO), borage and blackcurrent oils. It is also found in safflower, sunflower, corn, grape and sesame oils.

EPO, borage and blackcurrent oils also contain another fatty acid - gamma linolenic acid, or GLA. This is particularly useful for people who are deficient in the enzyme delta-6-desaturase.

GLA is made from LA (omega-6) in people who have sufficient levels of delta-6-desaturase. Those high in cholesterol, alcohol, monounsaturated + saturated fatty acids, trans fatty acids, processed vegetable oils, heated oils and/or sugar consumption are generally deficient. Other factors promoting deficiency include zinc deficiency, viral infections, aging and diabetes. People familiarising with any of this, should benefit from EPO supplementation.

Generally, simultaneous EPO and fish oil supplementation is required, as EPO works on the omega-6 pathway, whereas the fish oils work on the omega-3 pathway. Both require the delta-6-desaturase enzyme and are required in proportion to one another, so use both for the best results. Western diets tend to be rich in omega-6, but lacking in omega-3.

With EPA and DHA being enormously sensitive to light, heat and air, always ensure you buy these in opaque capsules, the darker the better. Also, be cautious of a 'fishy' taste. This usually indicates a degree of rancidity of the contained oil. Rancidity basically means the oil has started to deteriorate. Always buy oils in dark bottles or tins and in small quantities, as this helps minimise exposure to air, heat and light. Keep oils in the fridge, or in a dark place, such as a cupbord for best storage results. Also note that flavoured oils (eg: chili) have a shorter shelf life - usually about 6mths. Always look for supplements that are unrefined. If your supplement has been refined or deodorised - do not buy it.

TRANS FATTY ACIDS…why are they so bad?

Trans fats should be avoided, along with hydrogenated oils (contained in most processed foods). Diets rich in saturated oils or trans-fatty acids raise blood cholesterol, increasing the risk of heart disease. Aim to reduce the intake of saturated and trans-monounsaturated fats (found in animal fats, biscuits, pastries, margarine etc) and increase the intake of cis-monounsaturated oils (eg: olive oil) and polyunsaturated fatty acids (flax, sardines, tuna).

Trans fatty acids interfere with the bodys ability to utilise EFA's.

Hydrogenated oils (eg: margarine) raise 'bad' cholesterol (LDL's) and also lower the 'good' or protective HDL cholesterol. LDLs are often linked to chronic diseases such as heart disease. Hydrogenation refers to the addition of hydrogen molecules, which changes the natural structure.

DEFICIENCY SIGNS AND SYMPTOMS

Omega-6

  • Eczema
  • Hair loss
  • Behavioural disturbances
  • Kidney and liver degeneration
  • Excessive loss of water through the skin
  • Susceptibility to infections
  • Slow wound healing
  • Sterility in males, miscarriage in females
  • Inflammatory conditions like arthritis
  • Heart and circulatory problems

Omega-3

  • Growth retardation
  • Weakness
  • Vision impairment + learning disability
  • Motor in-coordination
  • Tingling in arms and legs
  • Behavioural changes
  • High TAGs (fats), and blood pressure and sticky platelets
  • Tissue inflammation and oedema
  • Dry skin
  • Mental deterioration
  • Low metabolic rate
  • Immune dysfunction
EFA deficiency commonly occurs in situations of malabsorption (eg: leaky gut, Crohns disease, etc).
Deficiency of the EFA's or of the omega 3 PUFAs alone can usually be corrected by consumption of oils and foods rich in these. Aim for approximately 2% of the total dietary intake to be comprised of this (approx 5g/day for women and 7g/day for men).

BENEFITS OF EFA's

Cardiovascular health

  • Improve peripheral circulation
  • Maintain healthy cholesterol/TAG levels
  • Keep blood viscous

Pain relief

  • EPA/DHA is capable of inhibiting inflammatory mediators, providing temporary relief for joint pain, stiffness, inflammation and swelling associated with rheumatism and arthritis

Pregnancy and lactating women

  • Pregnancy and lactation increases the need for omega 3's. DHA in fish oil is essential for normal development and functioning of the retina and brain, particularly before birth. Omega 3's are necessary for normal growth and development

Enhanced general wellbeing:

  • EFA's are an important component of all cells within the body. They form the phospholipid membranes of all cells throughout the body, helping maintain stability and fluidity of cell membranes.

ASSORTED OILS

Corn oil

  • Mostly polyunsaturated
  • High in vitamin E

Sunflower

  • Polyunsaturated
  • One of the richest sources of vitamin E

Peanut

  • Monounsaturated
  • Nutty flavour and yellowish colour
  • Clouds and gels if refrigerated
  • Fairly stable
  • Contains vitamin E
  • May help blood lipid levels

Hazelnut

  • Monounsaturated
  • One of the richest vegetable oil sources of vitamin E

Soybean

  • Polyunsaturated
  • High in linoleic acid, helping lower cholesterol
  • Excellent source of lecithin, fatty acids and phytosterols
  • Unfortunately most of it is refined and partially hydrogenated, the latter of which can actually increase risk of disease - so be sure to check how it has been made before buying

Sesame

  • Both poly and monounsaturated
  • Poorest vege oil source of vitamin E
  • May help to lower cholesterol
  • Choose the unrefined and untoasted oil

Grapeseed

  • Polyunsaturated and high in vitamin E
  • High in linoleic acid

Olive

  • Monounsaturated
  • Extra virgin comes from the first pressing and is the highest quality
  • Other grades use solvent extraction and are lighter in colour/flavour

Canola

  • Monounsaturated
  • Genetic engineering of the rapeseed fathered this oil
  • Rich in monounsaturates, first produced in the 1970's
  • Often contains a blend of other oils

Macadamia

  • Australian native!! From our rainforests on the East coast
  • Lots of monounsaturates and is unique in containing high levels of palmitoleic acid

Hemp seed

  • Contains high levels of linoleic acid (LA) and linolenic acid (LNA)

Flaxseed

  • Highest level of LNA amongst all the edible seed oils
  • Particularly important for vegetarians as it's a good source of omega-3
  • Use in salads with a simple vinegarette with a dash of orange juice to soften the slightly bitter taste

Walnut

  • Unrefined so best to store in opaque containers, protected from light, oxygen and heat
  • Contains over 50% of LA and a small amount of omega-3's
Remember, no matter how good the oils are, they still contain 120 calories per tablespoon.

By
Tiina Kallio B.Hsa., ND


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