Fats and oils are an aspect of nutrition that many runners find confusing, and so we’re going to start by considering the most common types of dietary fat before going on to identify which fats, and how much of them to include in your diet.
Types of fats & oils
Fats in foods are largely a mix of saturated, monounsaturated and polyunsaturated fatty acids and it’s the type of fat you eat that really matters when it comes to dietary and disease.
In general, the body uses fats:
- as an energy reserve
- for protection and cushioning of vital organs
- for insulation and temperature control
- as part of the structure of cell membranes in all body tissues
- as a source of antioxidants such as natural vitamin E
- to ‘carry’ the fat soluble vitamins A, D and E in the body
- to give taste and smell to food and to make some foods more tender
- to stimulate appetite and contribute to feelings of fullness
However, not all fats are created equal!
Saturated Fatty Acids (SFAs) – key points
SFAs are usually solid at room temperature e.g. butter, coconut oil, palm kernel oil and cocoa butter. They are generally found in animal products (meat, cheese, cream, milk, eggs, butter and lard) and in chocolate and many manufactured products (pies, pastries, cakes and biscuits).
Saturated fats can lower levels of high density lipoprotein (HDL), commonly known as ‘good’ cholesterol, and increase the levels of LDL, commonly know as ‘bad’ cholesterol. SFAs can also ‘block’ other metabolic pathways and prevent the effective use of essential fatty acids. SFAs are particularly harmful once they are hydrogenated, in the commercial process for making vegetable oils solid at room temperature, as this leads to the creation of ‘trans fats’ (see below).
A high intake of saturated fats has traditionally been associated with diseases such as atherosclerosis, heart disease and cancer and with rising levels of obesity, although this theory has attracted controversy in recent years.
Polyunsaturated Fats (PUFAs) – key points
Polyunsaturated fats (PUFAs) are usually liquid at room temperature e.g. vegetable oils and the fats in most nuts. They include the essential fatty acids (EFAs) – linoleic acid (omega 6) and alpha-linolenic acid (omega 3) – which we need to get from our diet on a daily basis. PUFAs lower LDL cholesterol, however high levels may still not be advisable, particularly for cooking, as these fats combine easily with oxygen in the body producing free radicals which can damage body cells.
Essential Fatty Acids (EFAs or omega fats) – key points
These polyunsaturated fats are ‘essential’ because we cannot manufacture them in the body and so we must get them from our diet. They are important precursors of other fatty acids we can make, e.g. arachidonic acid (AA), Eicosapentaenoic Acid (EPA), Dihomo-Gamma-Linoleic-Acid (DGLA) and Docosahexaenoic Acid (DHA) and that play important metabolic roles. EFAs are increasingly being studied for their role in athletic performance. Amongst other functions, they:
- provide the raw materials from which many anti-inflammatory chemicals are made – important for runners in reducing pain and inflammation
- are vital for the correct functioning of the brain, and for the nervous, immune and cardiovascular systems
- help to manage problems such as heart disease, cancer, PMS, menopausal problems, arthritis and skin complaints
- help to speed up metabolism making them important for weight control
- help prevent dry, scaly skin (omega 3)
- play a very specific, beneficial role in neural development in babies and infants
- may improve muscle function and recovery under endurance conditions.
Monounsaturated Fats (MUFAs) – key points
These fats are also usually liquid at room temperature although they may solidify when cooled (e.g. in the fridge). They are found in the highest quantities in olive oil, rapeseed and groundnut oil, olives, many nuts and avocados. They are also found in all types of fats, most dairy produce, eggs, fish and meat. Olive oil contains mainly omega-9 fats and is particularly stable.
Monounsaturated fats are thought to lower LDL (‘bad’) cholesterol, but maintain, or even slightly raise, HDL (‘good’) cholesterol. Diets rich in mono-unsaturates (such as the typical Mediterranean diet) have been linked with lower rates of heart disease, increased life span, lower levels of obesity and cancer. Oils high in monounsaturates are also often rich sources of the antioxidant Vitamin E.
Trans Fatty Acids (TFAs) – key points
These are unsaturated fats that do not generally occur naturally. They are produced in food processing through hydrogenation which makes liquid oils hard at room temperature and changes the molecular structure of the original fat. They are also produced when fats are heated to high temperatures e.g. in deep fat frying. Trans fats are most frequently found in hard margarines, cooking fat and mass-produced baked goods such as biscuits, cakes and puddings, soft margarines and fried take-away foods. They are often identified on the label as ‘hydrogenated vegetable fat’ or ‘partially hydrogenated vegetable fat’.
Cholesterol – key points
Cholesterol is present in many foods of animal origin including meat and dairy products, eggs, fish (especially shellfish) and many fatty manufactured products. We need a certain amount of cholesterol for metabolic and structural functions in the brain, nervous system, liver and blood. Low levels of cholesterol have been firmly associated with depression, anxiety, irritability, violence, suicide and insomnia.
About three-quarters of the cholesterol we need is manufactured in the body by the liver with only about one quarter coming from the diet. Dietary cholesterol has a fairly small effect on blood cholesterol levels, although it can be a problem for a very small percentage of people who have a genetic tendency to make too much cholesterol. Cholesterol only becomes an issue in the body when it is damaged through oxidation.
Triglycerides – key points
Triglycerides in plasma are derived from fats eaten in foods or are made in the body from other energy sources like carbohydrates. Excess triglycerides are stored in fat cells where they can be released under hormonal control for later use as energy.
Using fats for energy
At a moderate level of exercise intensity, carbohydrates and fat are almost matched with regard to providing fuel for muscles. In a 90-minute endurance event at race pace, virtually all the extra fuel needed to work at a higher intensity comes from muscle glycogen stores and circulating blood glucose. However, these carbohydrate reserves are limited and so we can only keep going at this level for about 1½-2 hours. If we don’t refuel with carbohydrates, we will have to slow to a pace where we can return to using fat as the main source of fuel for muscles.
Intake of fats and oils in non-elite marathon runners
Participants in the survey of dietary practices in non-elite marathon runners were largely on target for the intake of saturated and monounsaturated fat as a recommended percentage of total energy intake, and had a very low intake of trans fat. However, intake of total polyunsaturated fats, including the essential fatty acid (EFA) omega 3, was slightly below the UK recommended levels. Around a third of participants did not eat oily fish or fresh nuts, and over 50% did not eat seeds. Only 17% were taking fish oil supplements. All of these foods are useful dietary sources of omega-3 fatty acids that runners need in their diet to benefit from their properties.
Dietary sources of fats and oils for runners
Guidelines for fat intake are more complicated than those for carbohydrates and protein with runners being advised to obtain up to 30% of their total calorie intake from different types of dietary fat - 80% from monounsaturated and polyunsaturated sources, and just 20% from saturated sources. These guidelines would equate to 78 grams/fat/day for the average women on a 2,000-calorie diet, and 97 grams/fat/day for men on a 2,500-calorie diet.
Including fats in your daily diet
For essential fatty acids (EFAs):
- eat 1-2 tablespoons of cold-pressed oil (sesame, sunflower, pumpkin, flaxseed/linseed, hemp, walnut, avocado or extra virgin olive oil) or
- 1-2 dessertspoons of seeds (e.g. pumpkin, sunflower, sesame, hemp, flax/linseeds) a day. Either eat whole or grind in a coffee grinder and sprinkle on vegetables, soups, salads, cereals. Keep in the fridge for 2-3 days and
- 6-8 large nuts (e.g. walnuts, brazils, pecans) or 12-15 small nuts (e.g. almonds, cashews, pistachios) per day excluding peanuts.
- eat deep-ocean oily fish (e.g. salmon, herring, trout, mackerel, sardines, anchovies, fresh tuna) 2-3 times* per week as a direct source of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These EFAs are in a form that the body can use directly.
Choose fish, chicken, nuts and beans on a regular basis and include lean cuts of red meat once or twice per week.
Keep an eye on your intake of cheese, cream and ice cream and enjoy these foods as treats.
Store all nuts, seeds and their oils in a sealed jar in the fridge away from heat, light and air.
Use plant oils such as extra virgin olive oil for salad dressings, and non virgin olive oil, sunflower oil or vegetable oil for frying as they can withstand higher temperatures before breaking down and releasing free radicals. Avoid fried food, burnt or browned fat.
Use measuring spoons or spray cans to control portions of salad dressings and oils.
Check food labels for trans fats particularly in the form of hydrogenated or partially hydrogenated oils even though many food manufacturers have removed these fats from their products. Avoid fried foods, biscuits and other baked goods in restaurants unless you know the restaurant has removed trans fats and ask for sauces and gravies ‘on the side’ so you can control the portion size.
Check food labels for the quantity of fat. 20g or more of fat per 100g of food is a LOT of fat, 3g or less of fat per 100g of food is very little fat.
Remember that ‘low’, ‘reduced’ or ‘fat-free’ processed foods are not necessarily ‘healthier’ as food manufacturers often replace the fat in such products with refined grains or starch which can disrupt blood glucose metabolism.
Remember, too, that the biggest influence on blood cholesterol levels is the mix of fats and carbohydrates in your diet, and not the amount of cholesterol you get from food.
Sources of fats and oils for vegetarian and vegan runners
Part 9 of this series will focus exclusively on nutritional approaches for vegetarian and vegan runners. Vegetarian athletes who do not eat eggs or oily fish may have lower blood lipid levels of the omega-3 fatty acid DHA (docosahexanoic acid). Although the parent EFA, linolenic acid, can be converted to DHA, the conversion rate seems inefficient and can be disrupted by high intakes of omega-6 EFAs such as linoleic acid. Vegetarian/vegan runners may therefore wish to consider a supplement of DHA/EPA and we’ll look into this in more detail in part 9.
Actions for this week
- Use the guidelines above to look closely at the fat content of your diet in your Food & Training Diary and make sure you are including sources of fats that will support your marathon training programme.
- Try a new type of seed or seed oil e.g. pumpkin or walnut, or a new type of nut.
- If you eat fish, check that you are including oily sources at least twice per week*.
- Check that you are storing nuts, seeds and their oils correctly.
And if you need more help to build your personal nutrition plan, email Jane Nodder at firstname.lastname@example.org for details of individual nutrition coaching services for runners.
(*limit fresh tuna to one portion per week due to possible high pollution levels and check Government guidelines at www.food.gov.uk/ or www.nhs.uk if you are pregnant, trying to get pregnant or breastfeeding).
About Jane Nodder and Nutriworks
Jane Nodder works as a nutrition lecturer and clinic tutor on the MSc and BSc (Hons) Nutritional Therapy programmes at the University of Westminster, London. A qualified UK Athletics Leader in Running Fitness, Jane started running in 1986. As a club runner she runs track, cross-country, road, trail and endurance events and has completed eleven marathons, taking her PB from 4h21 to 3h37. Through her business, Nutriworks, Jane coaches groups and individuals in running and in translating general sports nutrition guidelines into practical, individualised nutrition programmes.
In 2010, Jane was awarded the Complementary & Alternative Medicine (CAM) Award for Individual Excellence in Nutritional Knowledge, and in December 2011 she gained the Yakult Prize for Outstanding Student of the Year for the MSc Nutritional Medicine at the University of Surrey.
For more information about running and nutrition coaching services from Nutriworks, visit www.nutriworks.co.uk