The Good and the Bad - Fats

The term “good fats” and “bad fats” can be misleading as both are used in the body for different processes but too much of the “bad fats” could potentially lead to adverse health outcomes. In this article I want to look at the three main fat categories; monounsaturated fats, polyunsaturated fats and saturated fats. I want to talk there roles in the body and what foods contain them.

Monounsaturated fats

It is recommended that the fats we should consume more of are both monounsaturated and polyunsaturated fats. Monounsaturated fats are fat molecules that have one unsaturated double carbon bond in the chemical molecule hence giving them the “mono” title. Found in foods such as olive oil, avocados, almonds, hazelnuts, pecans, sesame seeds and pumpkin seeds, monounsaturated fats can be extremely healthy for us in a well balanced diet. Remember that each gram of fat contains 9 calories so it’s important not to overeat any fats. Recommendations for monounsaturated fat consumption is about 10-20% of your daily calories (total fat intake equals 20-30% of overall intake), so for example, a 2000 calorie intake would consume about 22-44g of monounsaturated fats. Monounsaturated fats are good for two reasons; firstly they help boost HDL levels in the body. HDL (high density lipoprotein) has the ability to pick up LDL (lower density lipoprotein) in the blood and shuttle it back to the liver like a big fluffy uber. Secondly, is has the ability to lower blood concentrations of LDL through an increase in expression of LDL receptors on the liver. This in turn helps to reduce the risk of heart disease.

Polyunsaturated fats

Polyunsaturated fats are split into two sub groups (there is a third but I will leave that for today). You have the omega 3s which are found in fish (such as salmon and tuna), walnuts, pine nuts, flaxseeds and sunflower seeds (not as active as the seafood sources). The second group are the omega 6s which are plant based oils found in soybean, sunflower, flaxseed, safflower, grapeseed and poppyseed. Most people get enough omega 6s in their diet but it is recommended that two portions of fish are consumed a week, with one of them being an oily fish, to get enough omega 3s in the diet. I feel this should be the minimal amount of fish (especially oily) you try and consume a week. Fish in general is low in saturated fat and high in protein. Anybody looking for body composition changes or keeping a healthy weight should look at fish as a good dietary requirement. Health benefits of polyunsaturated fats are plentiful. They have strong anti-inflammatory properties which in turn will reduce disease risk. Inflammation plays a role in heart disease by causing damage to the artery walls. Polyunsaturated fats also have the same ability as monounsaturated fats by reducing LDL levels in the blood and even though they lower HDL levels, it decreases LDL levels more substantially, which in turn increases the HDL:LDL ratio. Healthy levels of HDL cholesterol in men is 1 mmol/L or above and for women it’s 1.2 mmol/L or above, and as for LDL levels for men and women it’s 4 mmol/L or below. Total cholesterol to HDL cholesterol ratio should be a score of 6 or below.

Saturated Fats

Known as the “bad fats” saturated fats have the opposite effect on cholesterol in the body compared to both monounsaturated and polyunsaturated. Saturated fat can decrease the expression of LDL receptors on the liver which in turn increases the amount in the blood. The increase of LDL is important for the formation of atherosclerosis which can then lead to heart disease or a heart attack. The LDL particle is small and can burrow it’s way into small gaps within the artery walls causing the start of atherosclerosis formation. Decreasing the amount of LDL in the blood will decease this incidence as much (some amount of atherosclerosis is a natural part of ageing) or slow the rate down. Also increasing foods that increase HDL levels is also a good way to slow down atherosclerotic build up. If you would like for information on saturated fats and how they can cause heart disease I have shared a link at the end of this article.

Foods that are high in saturated fats are red and processed meats, cakes, biscuits, pastries, cheese and butter. All the foods that taste good right! The NHS guidelines state that men between the ages of 19-64 shouldn’t consume more than 30g of saturated fats a day, and for women the number is no more than 20g a day. Remember the notion of “everything in moderation”.

Trans Fats

Trans fats are made when liquid oils are turned into solid fats, like margarine. They are used in processed foods, fried foods and can be found naturally in some meat and dairy. They have a similar effect as saturated fats by raising LDL cholesterol in the blood, however it lowers the “good cholesterol” HDL which is not good. This in turn can lead to high cholesterol and cardiovascular disease. There is also some evidence to suggest that high intake of trans fats could lead to some cancers and diabetes.

The NHS website states that adults shouldn’t consume more than 5g of trans fats a day.

Final Thoughts

My own personal dietary advice would be to structure your diet around monounsaturated and polyunsaturated fats with small amounts of saturated fats, and even smaller amounts of the trans fats. Consuming monounsaturated and polyunsaturated fats will give you the best results in regards to lower cholesterol, lower risk of cardiovascular disease, and lower risk of cancers and diabetes.

Saturated Fatty Acids and Risk of Coronary Heart Disease: Modulation by Replacement Nutrients.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943062/