FATS AND BLOOD CHOLESTEROL
As well as being a highly concentrated source of energy and a carrier for fat-soluble vitamins, fats provide food with a pleasant mouth feel and carry many of the flavours that make certain dishes taste delicious. Current dietary guidelines advise people to eat less saturated fat to help improve blood cholesterol levels, a major risk factor for heart disease and stroke. Will simply eating less saturated fat improve your blood cholesterol or is it more complicated than that?
WHAT IS CHOLESTEROL? Cholesterol is a kind of fat that is a part of all of our body’s cells. It is essential for many metabolic processes, including the production of hormones (e.g., oestrogen and testosterone), vitamin D and bile for digesting fat, and absorbing fat-soluble vitamins from foods. It is produced by the liver and also made by most cells in the body.
WHERE DOES CHOLESTEROL IN FOODS COME FROM? Cholesterol is only found in animal foods like meat, poultry, seafood, dairy and eggs. Plant foods like fruits, vegetables, legumes and grains do not contain any cholesterol in their natural state.
WHAT ABOUT BLOOD CHOLESTEROL? Cholesterol is carried around in the blood by little “couriers” called lipoproteins, which include:
- LDL cholesterol Low density lipoprotein (LDL) cholesterol, takes cholesterol from the liver to the rest of the body’s organs. When levels are too high, cholesterol can build up in the walls of blood vessels, eventually blocking them. Having high levels of LDL in the blood is therefore a risk factor for heart disease and stroke. Aim for an LDL cholesterol level less than 2.0 mmol/L (77 mg/dL).
- HDL cholesterol High density lipoprotein (HDL) cholesterol, seems to protect against cardiovascular disease because it clears cholesterol from our blood vessels and helps in its removal from the body. Having low levels of HDL in the blood is therefore a risk factor for heart disease and stroke. Aim for a HDL cholesterol level of at least 1.0 mmol/L (39 mg/dL).
The main nutrients in food that cause LDL cholesterol levels to rise are saturated and trans-fats, not cholesterol. However, if you eat a diet high in saturated fat, eating high cholesterol foods can raise some people’s blood cholesterol levels by an additional 10-20%. On the other hand, polyunsaturated and monounsaturated fats can help lower LDL cholesterol levels and raise HDL cholesterol.
The Heart Foundation currently recommends that we consume less than 10% of energy from saturated fat and less than 1% of energy from trans-fat. Dietary Guidelines recommend we consume 20-35% of energy from fat in total. Therefore, the optimal ratio for saturated and trans fats to unsaturated fats is no more than 1 : 2, or 0.5 if you prefer (this is what we use for recipes in GI News). In other words, for every gram of saturated fat, make sure you consume 2 or more grams of poly or monounsaturated fat.
It is of course important to note that no one has, or is, recommending complete avoidance of saturated fat, or foods high in saturated fat – it’s the balance that counts. It is therefore ok to enjoy butter instead of margarine as long as you have olive oil, fatty fish, nuts, seeds, etc…to balance it out.
- Reversing Diabetes (Murdoch Books), Dr Alan Barclay
- Heart Foundation: Saturated and trans fat
- Serum Triglycerides and Atherosclerotic Cardiovascular Disease: Insights from Clinical and Genetic Studies
Alan Barclay, PhD is a consultant dietitian and chef (Cert III). He worked for Diabetes Australia (NSW) from 1998–2014 . He is author/co-author of more than 30 scientific publications, and author/co-author of The good Carbs Cookbook (Murdoch Books), Reversing Diabetes (Murdoch Books), The Low GI Diet: Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment, New York).