When your fats are measured by your doctor, they usually measure triglycerides, total cholesterol, LDL, HDL and the ratio between them. The tests do not measure individual levels of essential fatty acids such as the omega series, this is only done with a more elaborate micronutrient test. But what are the idea levels and what do they mean?
These are an ester of three fatty acids combined with glycerol – they are a major energy source in the body and blood stream. When the body requires fatty acids as an energy source, the hormone glucagon signals the breakdown of the triglycerides by lipase to release free fatty acids then following further breakdown – glucose. These fats are the first to be used up when we expend energy so drop in the blood stream when we fast. Ideally our fasting triglyceride levels should be < 1.7 mmol/l.
We tend to think that cholesterol is bad but it is actually essential for all animal life. It is an vital structural component of animal cell membranes that is required to maintain both structural integrity and fluidity. It serves as a building block for the synthesis of steroid hormones made in the adrenal glands (cortisol and aldosterone), bile acids, vitamin D as well as the sex hormones progesterone, estrogens, and testosterone. Ideally the blood level of total cholesterol should be <5 mmol/l or if you have other cardiac risk factors such as diabetes, high blood pressure or family history <4 mmol/l.
Cholesterol can be absorbed directly from the gut from animal sources or can be made by many cells in our body but mainly those in the liver with the help of the enzyme HMG-CoA reductase (the target for statins). Cholesterol is transported around the body in the lipoproteins. A lipoprotein with a low protein : cholesterol ratio is called a low density lipoprotein (LDL), one with a high protein : cholesterol ratio is a high density lipoprotein (HDL). Ideally blood levels of LDL should be <3.4 mmol/l, HDL should be >1.6 mmol/l.
When we have too much cholesterol in our bodies either through excessive dietary intake of unsaturated facts or unregulated synthesis, excess LDL begin to appear in the blood. These LDL molecules are then oxidised and taken up by macrophages, which become engorged and form foam cells. These foam cells become trapped in the walls of blood vessels and contribute to atherosclerotic plaque formation. These plaques are the main causes of heart attacks, strokes, peripheral vascular disease and many other degenerative disorders hence why LDL cholesterol is known as the bad” cholesterol”. On the other hand, HDL transport cholesterol back to the liver, either for excretion or for other tissues that synthesise hormones. Large numbers of HDL particles correlates with better health outcomes and lower risk of vascular disease and hence its nick name – “good cholesterol”.
The trouble is, in a western society the levels of cholesterol in bad fats are usually too high compared to good fats.
What can we do to lower total cholesterol and LDL?
As well as increasing total energy uptake with physical activity, diet plays a role in blood cholesterol levels. Total energy intake should be reduced so the body not having to cope with all these excess energy stores. Fasting a day a week is a good way to get your body to reverse the process of energy storage and encourage energy consumption.
Reducing the consumption of high energy foods such as saturated and trans-fats is important. All fatty foods contain different proportions of saturated and unsaturated fat but examples of foods containing a high proportion of saturated fat include animal fat products such as cream, cheese, butter, ghee, suet, tallow, lard, pastries, and fatty meats. Certain vegetable products have high saturated fat content, such as coconut oil, cottonseed oil, palm kernel oil and chocolate (primarily from its cocoa butter). Many prepared foods are high in saturated fat content, such as pizza, dairy desserts, bacon and sausage. Many fried, fast foods are high in trans-fats. Reducing the intake of these is important but is not the only answer.
Replacing dietary carbohydrates with monounsaturated and polyunsaturated fats has been shown to lower serum LDL and total cholesterol levels and increase serum HDL levels, while replacing carbohydrates with saturated fat was shown to increase HDL, LDL, and total cholesterol levels. Trans fats have been shown to reduce levels of HDL while increasing levels of LDL.
So we need to reduce our carbohydrate and saturated fat intake and increase our intake of monounsaturated and polyunsaturated fats, but what are they:
Polyunsaturated fats mainly consist of the omega 3 and 6 series of fats. As well as a source of energy, they are essential for maintaining a healthy immunity, brain function, skin and joints as well as may other vital biochemical and inflammatory pathways. They cannot be synthesized by our bodies so have to be ingested (like vitamins) and for this reason they are known as essential fatty acids.
The more common varieties of omega 3 essential fatty acids include:
- The short chain omega 3 fatty acid – alpha-linolenic acid (ALA): found in chia, flaxseed, nuts (notably walnuts), healthy vegetables and some unprocessed vegetable oils.
- The long chain omega-3 fatty acids – eicosapentaenoic acid (EPA) and docosahexaeonic acid (DHA): found in fish oils, fish, algae, krill, and some meat from animals which eaten grass (eg venison and lamb). If needed, the long chain omega 3’s can be made, by the body, from the short chain varieties.
The more common varieties of omega 6 essential fatty acids include:
- Linoleic acid (LA)
- Gamma linoleic acid (GLA)
- Di Homo gamma linoleic acid (DGLA)
- Arachidonic acid (AA)
- Dietary sources of Omega 6 oils include nuts (particularly walnuts), grape seed oil, soya, flaxseed, most vegetable oils and oily vegetables such as avocado.
Monounsaturated fats mainly consist of the omega 7 and 9 series of fatty acids. These can be made in the body or ingested so are not completely classed as essential. Adequate intake is still important as they protect our cells as they have antioxidant as well as DNA repair properties. Monounsaturated fats are found in high fat fruits (Kiwi’s) and nuts such as olives, avocados, cashews, whole grain wheat, oatmeal and popcorn. High concentrations are also found in vegetable oils particularly olive oil, canola oil, grapeseed oil, groundnut oil (peanut oil), sesame oil, corn oil, safflower oil, almond oil, sunflower oil, hemp oil, tea-oil Camellia, and avocado oil.
The different varieties of omega 7 fats include:
- Palmitoleic acid and vaccenic acid found in macadamia nut oil and sea buckthorn oil.
The different varieties of omega 9 fats include:
- Erucic acid, which is found in rapeseed, wallflower seed, and mustard seed.
- Oleic acid which is a main component of olive oil, macadamia oil which in particular has been shown to reduce blood saturated fat levels and lower the incidence of atherosclerosis, diabetes, inflammatory and autoimmune diseases, skin wrinkling and skin ageing.
We are becoming deficient in fatty acids
Several studies have shown that, in the west, we are becoming increasing deficient in essential fatty acids particularly the omega-3 series. We are eating less fish and the animals we eat are less likely to have eaten grass or insects. For example, an analysis of individuals who have bought the online Micronutrient test via cancernet.co.uk were published in the National Cancer Research Conference in Liverpool 2012. It was concerning that the results showed that 95% patients had sub-optimal levels in one or both of the long chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaeonic acid (DHA) or the short chain omega 3 alpha-linolenic acid (ALA) [Thomas et al 2012)