Saturated fat – What’s the story?

03 Apr

Saturated fat – What’s the story?

The debate about saturated fat and health has been ongoing for the last 70 years, so let’s take a look at some of the facts.

The history of the low-fat diet

The “fat-heart hypothesis” began in the 1950’s and claimed that dietary fat intake was linked to high cholesterol and heart disease (1).

In the 1950’s Ancel Keys began a 15-year study that involved over 12,000 middle aged men in seven different countries. The study found that a higher intake of saturated fat in north European countries was associated with increased serum cholesterol levels and heart disease in contrast with a higher intake of polyunsaturated fat in Mediterranean countries which saw lower serum cholesterol and heart disease (2). What followed was decades of advertising promoting low fat foods for health.

A few years later, Keys' study and other studies with the same conclusion of saturated fat and heart disease were found to be flawed. Other factors affecting cholesterol levels and heart disease such as trans fats had not been considered as well as the possible benefits of fibre, fish, fruit and vegetables from the Mediterranean diet on heart disease (3). The low fat movement steered people more towards a higher carbohydrate intake which led to increased body fat and cardiovascular disease risk (4).

So let’s go back to understanding fat.

What is fat exactly?

To answer this, we first have to look at fat: in the diet and in the body.

In the diet:

All fats are a mixture of saturated fats, monounsaturated fats and polyunsaturated fats in different proportions.

  • Saturated fats are found in high proportions in dairy products, meat, coconut oil and palm oil.
  • Monounsaturated fats (MUFAs) are found in high proportions in plants such as olives, avocados, seeds, nuts and vegetable oils. They are also found in high proportions in meat (5).
  • Polyunsaturated fats (PUFAs) are found in higher proportions in seeds, nuts, vegetable oils and oily fish. Omega 3 and omega 6 (vegetable oils) are also PUFAs and are classified as essential fatty acids meaning they need to come from your diet. Essential fatty acids are fats that cannot be produced by the body which we need from dietary intake such as omega 3 and omega 6 found in nuts, seeds, vegetable oils and oily fish.

Trans fats are sometimes found in processed foods and are produced by heating up polyunsaturated fat to make it more solid and to increase its shelf life. It's also produced using vegetable oils at high heat like deep frying. Trans fat is associated with reduced HDL cholesterol and inflammation (6).

Fat in the body is important for the following roles:

  • Supplies our reserve of energy
  • Protects organs
  • 70% of the brain is fat
  • Forms part of the cell walls
  • Forms hormones
  • Important for absorption of fat soluble vitamins
  • Keeps us warm

What are the current government guidelines?

Men are advised to have not more than 97 grammes of total dietary fat intake a day of which 30 grams should be saturated fat and women are advised to have 20 grammes of saturated fat a day.

Busting the saturated fat myth

Fat is one of the main macronutrients along with protein and carbohydrate and is essential in our diet. A meta-analysis concluded that there was not enough evidence to show that saturated fat was linked to increase CVD risk (7). Eating saturated fat is not the main issue for our health. The issue lies with a multitude of diet and lifestyle factors such as high sugar or simple carbohydrate diets, including trans fats or processed foods and meat in the diet and psychological, physical or physiological stress.

So what can you do?

The following list some healthy fat habits;

  • Cook from scratch with fresh foods to avoid processed or ready-made meals as much as possible as these may contain trans fats or processed grains.
  • Saturated fats are chemically more stable and better for cooking as they have a higher smoking point than MUFA’s and PUFA’s and are less likely to be damaged and oxidized. Avoid smoking of any fats as this changes the chemical structure of the fat and can be damaging to the body.
  • If you do want to fry foods, use coconut cooking oil for a short time at low heat.
  • Bake vegetables without oil and drizzle olive oil after baking.
  • Bake using lard, butter, ghee or coconut oil.
  • If you decide it’s essential to use oil for your cooking, use avocado oil which has a higher smoking point but limit use.
  • Avoid or reduce sugar foods and processed grains, as these are low in nutrients and fibre and broken down quickly to sugar. High sugar foods or the combination of high sugar foods and fats may increase inflammation, create an imbalance in cholesterol and body fat.
  • Use cold pressed virgin olive oil for salad dressings as it contains polyphenols which may be helpful for cardiovascular health.
  • Make sure you store oil in a cool dark cupboard with an air tight lid as oil can spoil with heat, light and air.
  • Choose organic free range meat which contains omega 3 fats as well as stearic acid, a type of cholesterol neutral saturated fat.

As always, any food or drink should be consumed in moderation. For more guidance on how to balance your fat intake along with other nutrients, please contact us to arrange a personalised nutrition consultation or dietary education session.

References

  1. Forouhi NG, Krauss RM, Taubes G, Willett W. Dietary fat and cardiometabolic health: Evidence, controversies, and consensus for guidance. BMJ. 2018;361.
  2. Menotti A, Puddu PE. How the Seven Countries Study contributed to the definition and development of the Mediterranean diet concept: A 50-year journey. 2014 [cited 2020 Mar 7]; Available from: http://dx.doi.org/10.1016/j.numecd.2014.12.001
  3. Temple NJ. Fat, sugar, whole grains and heart disease: 50 years of confusion. Vol. 10, Nutrients. MDPI AG; 2018.
  4. DiNicolantonio JJ. The cardiometabolic consequences of replacing saturated fats with carbohydrates or ω-6 polyunsaturated fats: Do the dietary guidelines have it wrong? Vol. 1, Open Heart. BMJ Publishing Group; 2014. p. e000032.
  5. Harcombe Z. To cite: Harcombe Z. Br J Sport Med [Internet]. 2019 [cited 2020 Mar 16];53:1393–6. Available from: http://bjsm.bmj.com/
  6. Mozaffarian D, Clarke R. Quantitative effects on cardiovascular risk factors and coronary heart disease risk of replacing partially hydrogenated vegetable oils with other fats and oils. Eur J Clin Nutr [Internet]. 2009 May [cited 2020 Apr 3];63:S22–33. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19424216
  7. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr [Internet]. 2010 Mar 1 [cited 2020 Mar 15];91(3):535–46. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20071648
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