Sue Bedford (MSc Nutritional Therapy)
We need fat for our bodies to function effectively in every stage of life – but not all fats are created equal when it comes to how they benefit the body and health.
Many research studies over the last decade have discovered that when it comes to dietary fat, the focus should be on eating more of the ‘healthy’ fats such as omega 3 fatty acids along with monounsaturated and polyunsaturated fats (as well as some saturated fat) and less of other, not so ‘healthy’ fats such as the Trans fats. Fat is needed in our diet for a variety of reasons including:
- Healthy skin
- Cell membranes
- Absorption of fat- soluble vitamins (A, D, E and K)
- To provide the essential fatty acids – Linoleic and Linolenic acid (the body cannot make these itself or work without them).
- Brain development
- Control of inflammation
- Blood clotting
- Production of oestrogen and other hormones
What are Trans-fats?
Trans fats are a form of unsaturated fat. There are two main types: natural and artificial. Natural are found in some foods at very low levels, such as those from animals, including meat and dairy products ie milk and cheese.
Artificial trans fats are liquid vegetable oils that have been turned into semi solids or solids by a process called hydrogenation (bubbling it through hydrogen) and are in thousands of pre-prepared foods to give texture and a long shelf life. This process is known as Partial Hydrogenation. The end product is a fat that doesn’t turn rancid as readily as non-hydrogenated oil.
It is the artificial trans fats that we need to be most concerned about. There is limited evidence at present re the effect on the body of natural trans fats but from what evidence there is natural trans fats appear less harmful than artificial trans fats. There is no ‘safe’ level of trans-fat consumption to the body.
Examples of SOME foods that may contain trans fats (check the label for partially hydrogenated fats or hydrogenated fats):
- Vegetable shortening
- French fries/some chips
- Most things that are battered or fried
- Cake mixes
- Some crackers
- Some frozen pizza dough
- Non dairy coffee creamers
- Some ice creams
- Some types of microwavable popcorn
- Frozen microwave meals
How can Trans- fats affect health?
Trans fats provide no nutritional benefit and can increase the risk of heart disease, raise LDL (bad) cholesterol and reduce HDL (cholesterol), strokes, diabetes and may also increase inflammation in the body.
Trans fats and fertility
Consumption of trans fats can lead to obesity which may impact on fertility by affecting ovulation, increasing insulin resistance and by increasing inflammation. Trans fats may amplify the symptoms of PCOS and endometriosis in some women.
Researchers from Harvard Medical School investigated 18,800 women and looked at the effect of trans fats on fertility. They discovered that the more trans fat in the diet, the greater the chance was of developing ovulatory infertility (Chavarro et al 2007). This could be explained by the fact that eating more of these fats usually means eating less of another type of fat or carbohydrate. Trans fats increase inflammation throughout the body, interfering with ovulation, conception and early embryonic development and this may affect IVF success. Eating monounsaturated fats instead of carbohydrates or trans fats may support fertility, ease inflammation and improve the body’s sensitivity to insulin. The United States Department of Agriculture’s Dietary Guidelines for Americans recommend that trans fat intake should be as low as possible (U.S Department of Agriculture 2005). Some experts believe they should be avoided completely as they impair fertility by affecting ovulation.
What can be done to avoid trans/hidden fats?
- Start reading labels. Avoid foods that contain trans fats (look for the words partially hydrogenated oil or hydrogenated fats in the ingredients). Check Mayonnaise, salad dressings, packaged foods – in particular. Make your own salad dressings, cakes, mayonnaise.
- Buy fresh local food – go to your local butchers/farmers markets and fishmongers – buy food seasonally.
- Eat whole foods in their natural state. Focus on fresh vegetables, fruits, organic meats and fish. Introduce more smoothies and juices into your diet and ensure that they contain some vegetables where possible.
- Avoid fast foods- French fries, hamburgers, fried chicken… are all cooked in trans fats.
- Cook from scratch at home where possible – if you are short on time try batch cooking so you can pull home made food out of the freezer for after a busy day as this is where it can be tempting to opt for an easy take out alternative.
Overall, the take away from this article, for health and to increase chances of pregnancy is: increase the reduce /eliminate the artificial trans fats, consume monounsaturated and polyunsaturated fatty acids and go easy on the saturated fats (saturated fats should not exceed more than 8% of your daily calories.
Chavarro, J., Rich-Edwards, J., Rosner, B. and Willett, W. (2007) Dietary fatty acid intakes and the risk of ovulatory infertility. American Journal of Clinical Nutrition, Vol. 85, No. 1, pp231-237.
Missimer, S. et al.,(2010) Trans fats linked to increased endometriosis risk and omega-3-rich food linked to lower risk. European Society of Human Reproduction and Embryology.