Fats, also known as lipids, used to be considered to be unhealthy. However, it is known that many fats are beneficial and some are essential for health. Only certain fats are unhealthy.
Due to their complex history within dietary research, there are many misconceptions about fats and even literature from official sources may contain inaccuracies.
The Chemical Composition Of Fats
Lipids are biological compounds composed of carbon, hydrogen, and oxygen.
Lipids occur within the body as fats, phospholipids, and steroids.
Because the goal of this academy is to introduce you to the nutritional considerations related to fats, we’ll concentrate on saturated fats, polyunsaturated fats and mono-unsaturated fats rather than the other lipids that are present within the human body.
Structurally speaking, saturated fats, polyunsaturated fats and monounsaturated fats are very similar. However, slight adjustments to their structure have huge physiological impacts.
Saturated fats are triglyceride molecules with fatty acid chains of varying length that are that are saturated by hydrogen molecules.
This means that the fat molecule is carrying as many hydrogen atoms as possible, all atoms are joined by single bonds, and the fatty acid chains are relatively straight.
Unsaturated fats also have fatty acid chains of varying length, but the fatty acid chains are not fully saturated with hydrogen atoms; double bonds exist in the molecule.
A double bond creates a kink in the fatty acid chain that has physiological implications.
Mono-unsaturated fats have only one double bond in the entire molecule, while polyunsaturated fats have two or more.
There are lots of pictures and diagrams online which illustrate the structure of these different types of fats. Research on google images to find some.
What Are Saturated Fats?
Saturated fat is typically found in animal by-products such as red meat, butter and cheese.
Saturated fat can be identified easily, as it exists as a solid at room temperature. There is an artificial form of saturated fat known as trans fat created through a process known as hydrogenation.
This process takes an unsaturated fat (usually a vegetable oil) and saturates it with hydrogen atoms to remove the double bonds, which allows the oil to take a solid form at room temperature.
This process is often used when creating spreads, where the commercial benefit of having a solid spread disregards the health risks associated with artificially saturated fats.
The Functions of Saturated Fats
Saturated fat has some important functions in the body. For example, it is needed for healthy cell membranes and is involved in hormone synthesis.
A little saturated fat is therefore required in the diet. However, an excessive intake of saturated fat can contribute to raised cholesterol.
Many studies have indicated that saturated fats raise cholesterol which is transported to the artery wall by low density lipoproteins (LDLs) (as mentioned below) or back to the liver by high density lipoproteins (HDLs).
Damaged artery walls (by excess free radicals/ insufficient antioxidants) trap cholesterol. This contributes to:
- The hardening of the vessel walls (calcium deposits)
- Formation of Plaque
- High blood pressure
- And heart disease
Saturated fat also contributes to the formation of LDL (low-density lipoprotein), which promotes cholesterol production and transportation within cells.
Due to the health risks associated with consumption of high levels of saturated fat, official bodies currently recommended that less than 10% of calories per day be consumed in saturated fat.
This gives a daily allowance of about 20g for women and 30g for men. It is recommended that children consume less.
Some experts in nutrition contest that saturated fat is so harmful. There are also differing views about cholesterol as not all people with high cholesterol suffer from heart disease and some with low cholesterol may die from heart disease.
Research is still ongoing in this area.
Unsaturated fats can be found in many plant sources; nuts, seeds and their cold-pressed oils and to a lesser extent in legumes and dark leafy vegetables.
Common vegetable cooking oils such as canola oil, sunflower oil, olive oil and peanut oil all contain unsaturated fats. Most are not suitable for cooking at high temperatures as this destroys unsaturated bonds and makes them harmful.
Olive oil has a high level of monounsaturated fats and low levels of poly unsaturated fats.
What Are Polyunsaturated Fats?
Polyunsaturated fats are a form of unsaturated fats which consist of triacylglycerol molecules that contain at least two double bonds.
They exist as liquid at room temperature and when slightly chilled, and are found in nuts, vegetable oil and some animal foods such as eggs, meat and fish.
Common sources of polyunsaturated fats are canola oil, corn oil and sunflower oil.
The many double bonds make polyunsaturated fats delicate and prone to damage from heat and light. Damaged polyunsaturated fats may harm the body’s cells.
So buy cold-pressed nut and vegetable oils and keep them in a cool, dark place and do not use for cooking.
Cooking polyunsaturated fats at high temperatures denatures their bonds creating harmful chemicals known as free radicals which can damage body cells.
If using fat to cook at high temperatures it is actually safer to use saturated fats such as butter or lard.
Fish should also be consumed very fresh. Once it starts to smell fishy, the oils in the fish have started to go rancid and may have similar effects in the body as described above.
Frozen fish is often safer than fresh fish for this reason.
It is also very important to choose any fish oil supplement carefully. Cheap supplements are often inferior.
Essential Fatty Acids
Polyunsaturated fats encompass many different fats, including the essential fatty acids omega-3 and omega-6 which are necessary for proper function, yet cannot be synthesized within the body and need to be consumed.
Essential fatty acids are necessary for:
- Proper growth and development
- Renal function
- Reducing blood pressure
- Aiding in good mental health
- Maintaining skin and hair condition
They are converted in the body to prostaglandins which act locally to regulate hormones (helpful for PMS) and inflammation (helpful for eczema, asthma arthritis).
Additionaly, many epidemiological studies indicate that there is a connection between polyunsaturated fat consumption and decreased levels of LDL (low-density lipoprotein), which minimises the production and transport cholesterol between cells in the body.
Where to find Omega-3 and Omega-6 and what they do
Omega-3 fatty acids are required for cell function throughout the body so the contribute to well-being in many ways.
Omega-3 fatty acids have demonstrated to protect from heart disease.
Their consumption has also been linked to:
- Brain health and development
- Healthy skin
- Musculoskeletal health
One of their major benefits is their ability to damper down inflammation throughout the body.
Inflammation is increasingly recognised as being a factor in many conditions, so omega-3 fatty acids are often used as both prevention and treatment for conditions such as arthritis, cardiovascular diseases and many more.
Omega-3 fatty acids are found predominantly in oily fish, the best sources being salmon, herring, anchovies, mackerel and sardines.
Official sources recommend that oily fish should be consumed twice a week.
Some nutritional experts also recommend supplementation with omega-3 fish oils. Larger fish such as tuna contain small amounts of fish oils, but are likely to be contaminated with mercury.
It is very important not to consume too much of this type of fish particularly during pregnancy.
Although there are plant and nut sources of omega-3; namely walnuts, pumpkin seeds and flaxseed, these are not so readily converted in the body to the form required for assimilation.
It is thought that some individuals may lack the enzymes required to carry out the conversation of the fatty acid proir to use. Thus some individuals and vegetarians may be more prone to omega fatty acid deficiency.
Omega-6 fatty acids are found in nuts, seeds, vegetable oils, meat and eggs.
Baked goods such as bread, cakes and biscuits which contain vegetable oils also contain omega-6 oils.
Omega-3 and omega-6 fatty acids follow different metabolic pathways, thus have different effects in the body.
Whereas omega-3 fatty acids result in the release of anti-inflammatory prostaglandins, omega-6 fatty acids contribute to the release of inflammatory prostaglandins.
Both inflammatory and anti-inflammatory responses are required by the body at different times for different situatuoins.
Therefore, it is very important that the right amount of omega-3 and 6 fatty acids are consumed as prolonged release of proinflammatory prostaglandins is implicated in many chronic conditions including cardiovascular disease.
Maintaining a good balance of omega-3 and omega-6
The ideal ratio of omega-6 to omega-3 fatty acids is thought to be less than 4:1. Modern diets frequency contain a much higher ratio of omega-6 fatty acids, as much as 10 or 30:1. This is increasingly recognized as being potentially harmful to health.
The rise is due to the over-consumption of commercially baked and deep fried products (fast food), increased use of cereal (which contains omega 6) to feed livestock and the replacement of butter and lard with vegetable oil for frying and baking food.
To maintain a good balance it is advised to avoid too many commercially produced baked products as well as fast food.
Clients also need to be advised about which fats to cook with. In general, it is not advisable to heat vegetable and nut oils such as sunflower oil etc. to high temperatures, so these are unsuitable for frying and their use should be reserved for making salad dressing.
They may also eat grass-fed or free range meat and eggs as far as possible. Regular consumption of foods containing omega-3 fatty acids can also help balance the ratio.
Deficiency signs and symptoms for essential fats include:
Omega 3 fats – Dry skin, inflammatory health problems, water retention, tingling in arms and legs, high blood pressure, high triglycerides, prone to infection, difficulty losing weight, memory or learning ability declined.
Omega 6 fats – High blood pressure, PMS or breast tenderness, eczema or dry skin, dry eyes, inflammatory health problems, difficulty losing weight, blood sugar problems or diabetes, excessive thirst.
What are mono-unsaturated fats?
Mono-unsaturated fats are triglyceride molecules that contain only one double bond. They are more stable and so suitable for cooking.
Their function in the body is similar to that of polyunsaturated fats, with additional benefit of increasing the production of HDL (high density lipoproteins), which collect cholesterol from the body’s tissues and move it to the liver for removal.
- Olive oil
- Nuts and seeds
What are trans-fats?
although some trans fats can be found naturally in animal products, most trans fats in a western diet are unsaturated fats that have been altered to serve the commercial food industry.
To create a trans fat, an unsaturated fat is partially saturated with hydrogen atoms to increase shelf-life for use in commercially prepared goods.
The down-side of trans fats is that they promote the existence of LDL within the body and inhibit HDL production, which has an overall effect of increasing cholesterol levels.
Dietary sources of fats
Sources of saturated and trans fats
Saturated fats are typically found in animal byproducts such as red meat and full fat dairy products (milk, cream, cheese and butter).
There are a few plant sources of saturated fats; coconut milk, cocoa butter, and palm oil, but most of these plant sources are not used in day-today cooking, and generally only lurk in foods that should be consumed sparingly, such as baked goods and chocolate.
It is increasingly recongnised that plant sources of saturated fats do not contribute to health risks as much as animal fats.
Coconut oil (also solid at room temperature) is considered to have health benefits and is suitable for cooking as stable. Some forms of palm oil are also recognised as having health benefits.
A little organic butter is considered preferable to highly processed margarine’s.
Trans fats are commonly found in commercial spreads such as margarine, in fried foods, and in baked goods that need to extend their shelf-life.
They are also listed as hydrogenated fats and partially hydrogenated fats, so avoid these too.
The role of fats in the diet
Fat has a positive affect on the taste and texture of foods. They make food taste good. That’s why people like crisps. It’s why we have such a difficult time avoiding the fats that make our favourite foods taste the way they do.
Fat also emphasises the aroma of foods, making them seem more inviting while creating a feeling of satiety and fullness, fat in a meal keeps the food in the stomach for longer. Most of the foods we consider ‘comfort’ foods have high fat content.
Fat also supplies the body with energy; there are 9 calories per every gram of fat. After carbohydrates have been processed during digestion, fats are the next to be used to supply the body with energy.
Similarly, fat is used to store energy in adipose tissue. We are born with a specific number of fat cells, which increase or decrease in size depending upon energy requirements or calorie consumption.
Although having excessive fat stores can create health problems, there is some benefit to having some stored fat; fat serves as padding for our organs and bones.
Fat also works in concert with vitamins A, D, E and K. Without fat, we would not be able to absorb these fat soluble vitamins that have a positive effect on eyesight, blood circulation, hair and skin condition, and bone condition.
It recommends that 35% of calories consumed be from fat to ensure proper nutrient absorption and management of HDL and LDL.
Common Problems Associated with Saturated and Trans fats
All fat is not necessarily bad. For instance, the essential fats are known to be protective for the cardiovascular system, reducing insulin resistance, even helping the body burn saturated fat. However, here we will look at the common problems with fats.
Consuming trans fats, too many saturated fats and possibly too many omega 6 fatty acids over a long period of time can contribute to coronary artery disease, arthiosclerosis, heart attack and stroke.
Coronary artery disease develops as deposits of fat, cholesterol, calcium and other mineral build up in the blood vessels that supply blood to the heart muscle.
As the plaque forms in the vessel walls (arthiosclerosis), blood pressure increases as the diameter of the vessel decreases. High blood pressure is responsible for weakening the heart muscle, as well as chipping away pieces of plaque from artery walls.
When a piece of plaque breaks away from the vessel wall, it becomes engulfed in blood cells and forms a clot. This clot will travel throughout the body’s vascular system until it becomes lodged somewhere, and is likely to block off a blood vessel, starving an area of the body of blood.
If the clot becomes lodged in one of the coronary arteries, a heart attack will ensure as the heart muscle is starved of oxygen and begins to die. Survival depends upon the location the clot becomes lodged in, the health of the surrounding blood vessels, and proximity to healthcare.
Because of the high calorific density of fat, consuming a high fat diet puts individuals at risk of obesity. Fat is 9 calories per gram, a high calorie option considering that protein and carbohydrate are both only 4 calories per gram.
Every individual is born with a specific number of fat cells; this number does not change throughout life, irrelevant of weight increases and decreases.
Fat is the body’s primary means of long-term energy storage, as the energy stored in glycogen molecules is temporary and meant to be used between meals.
Excess energy is transferred into the adipose tissue, to be stored for the long-term.
However, people often consume more calories that are needed, forcing energy reserves that will never be called upon to develop and remain, therefore as the size of the fat cells increase, weight and body fat composition increases.
Clearly, being overweight is not something that people strive for. There are however, considerations beyond appearance.
Obesity exposes people to conditions such as:
- Heart disease
- Type II diabetes
- Arthirits (this is due to the strain that joints suffer when they bear more weight that they were intended to)
- Breathing problems (sleep apnoea, asthma)
Type II Diabetes
An obese individual is twice as likely as a person with healthy weight to develop type II diabetes.
Type II diabetes occurs when the pancreas does not secrete enough insulin, or when the body develops immunity to insulin.
When insulin is not being produced or used properly, carbohydrates storage is affected, and energy is not supplied to the brain and tissues effectively.
Managing weight through exercise and a healthy diet are integral to controlling type II diabetes and minimising the risk of developing the disease.
Superfoods: Nuts, seeds and oily fish
Nuts and their nutritional value
Nuts and seeds are great foods as they are so nutrient dense. They are a good source of protein, minerals and B vitamins. They contain good amounts of polyunsaturated fats which have been shown to have numerous benefits for the body.
Each nut and seed has a different nutrient profile. Here is a selection of some of the most nutritious nuts and seeds.
Almonds are high in calcium. They are also very alkaline, so are ideal for detox diets.
Walnuts contain omega 3 fatty acids and an unusual and beneficial form vitamin E called gamma tocopherol. The skin is also high in health giving phytonutrients. One study found that eating a handful of walnuts per day helped prevent heart disease.
Flaxseeds: These small yellow seeds contain omega 3 and 6 fatty acids. Their oil is often extracted and consumed. They are also high in phytoestrogens so may help with hormone balance in the menopause. Flaxseeds can really help with constipation. They are best eaten after soaking in water or with a glass of water.
Pumpkin Seeds these small green seeds also contain omega 3 fatty acids and zinc.
Sesame Seeds: These tiny seeds contain omega 3 and 6 fatty acids as well as many minerals including calcium. If you don’t like dairy products, add tahini (which is made from ground sesame seeds) to your smoothies, fruit salads and enjoy spread on toast too.
Brazil Nuts: Depending on where they are grown, brazil nuts can make a great source of selenium.
Cashew Nuts: These are high in calcium, but try not to east salted ones!
NB. Peanuts are not actually nuts. Although they are high in protein, they can also grow antitoxins which are harmful in large quantities. Peanut allergy is also on the increase. Great alternatives to peanut butter are almond or cashew butter.
It’s best to buy your nuts fresh and unsalted. They can be ground and added to smoothies, yogurt’s, energy bars, breads and cereals for added nutrition and to increase satiety.
Buts and seeds make great standby snacks as they are easily transportable. Eat them with fresh fruit for a sustaining snack which keeps your blood sugar levels stable due to the fat and protein content of the nuts and seeds. They can also be added to stir fries to give a lovely crunchy texture.
Salmon and Sardines
Everybody knows that oily fish is good for you due to its omega 3 content. Oily fish such as salmon also contain vitamin D and E, so it’s excellent for cardiovascular heath, bones and skin too.
Eating the bones of tinned or cooked salmon and sardines can also supply calcium. Tinned fish can be added to fish pies and fish cakes.
Sardines on toast are a great quick meal or snack which children may enjoy too. Make sure you drain the oil from the tin first and enjoy with rocket salad and wholemeal toast.