Fat

What is it?

Fat is a macronutrient which is required to be healthy. Having too much fat, and also not having enough, can be detrimental to health.

There are several different kinds of dietary fats in foods. They include unsaturated, saturated, and trans fats.

Unsaturated fats are liquid at room temperature and are beneficial because they can decrease inflammation, improve cholesterol, and stabilize heart rhythms. There are two types of unsaturated fats, they include monounsaturated and polyunsaturated. Omega-7 and 9 are different types of monounsaturated fatty acids. Omega-3 fatty acids are a type of polyunsaturated fat. There are three main types of omega-3 fatty acids, these include DHA, EPA, and ALA. Omega-6, also known as Arachidonic Acid, is a polyunsaturated fat, and may be pro-inflammatory.

Saturated fats are typically solid at room temperature. They are found in animal products and some plants including coconut, coconut oil, palm oil, and palm kernel oil. Saturated fats contribute to high cholesterol and heart disease, and the intake of them should be limited to support optimal health.

Trans fats are chemically made by heating liquid vegetable oils (unsaturated oils) with hydrogen gas, and a catalyst, in a process called hydrogenation. This process helps to make the fats more stable and less likely to turn rancid, therefore increasing the shelf-life and taste of products to which they are added. Because they withstand repeated heating without breaking down, they may also be used for frying. Trans fats are also naturally occurring in beef and dairy products, however in small amounts. Unfortunately, trans fats are the worst type of fat and have been shown to increase bad cholesterol, lower good cholesterol, cause inflammation, contribute to weight gain and insulin resistance, even in small amounts.

Cholesterol is worth mentioning here as it’s also a type of lipid that is found in foods as well as circulating in blood. The liver produces cholesterol naturally which results in some controversy over the dietary intake of cholesterol and its ability to affect blood levels of cholesterol. There are different kinds of cholesterol including LDL, VLDL, HDL, and TG, to name a few. Eating a diet high in saturated and trans-fat may contribute to increasing the bad cholesterol in our blood.

What other names are fats known by?

Unsaturated, polyunsaturated, monounsaturated, saturated, trans, lipids, triglycerides, fatty acids, phospholipids.

What do they do?

Dietary fat helps to give the body energy, supports the function of cells, keeps the body warm, protects vital organs, absorbs certain nutrients, and creates hormones. Fat is required for health.

In addition, healthy fats are important for supporting the health of the gut, whereas unhealthy fats can do the exact opposite. Studies have shown that unhealthy fats (saturated and trans) can cause an unwanted imbalance in the gut microbiome leading to uncomfortable gut symptoms and some diseases. Some studies have shown that a diet high in monounsaturated fats may also negatively affect the gut microbiota.

Healthy fats on the other hand, like polyunsaturated fatty acids, do not seem to negatively affect the gut microbiome and may contribute to decreasing inflammation present. In addition, there’s something called short-chain fatty acids which are produced by the gut microbiome in the colon, from the fermentation of dietary fibers and starches, which have been shown to decrease inflammation, promote weight loss, improve the body’s ability to absorb nutrients, and are thought to be a main player in the gut-brain axis.

Where do I get them?

Unsaturated fats come from plant-based foods such as vegetable oils, nuts, and seeds. Sources of monounsaturated fats include olive, peanut, and canola oils, avocados, almonds, hazelnuts, pecans, pumpkin, and sesame seeds. Polyunsaturated fats are found in sunflower, corn, soybean, flaxseed oils, walnuts, flax seeds, fish, and canola oil.

Saturated fats come from animals and some plant products such as coconut, and palm oil. Trans fats can be found in small amounts in beef and dairy products and in processed foods as a preservative and to improve taste.

When consuming a majority of protein from animal sources it’s important to pay attention to the total fat, saturated fat, and cholesterol in those foods The charts below, although not an exhaustive list, provide some further information.

Dairy Foods

Animal Foods

It’s important to know that plant-based sources of protein will contain almost none, if not zero, saturated fat and no cholesterol.

How much do I need?

For healthy individuals with no health concerns, fat should make up about 30% of nutritional intake. Saturated fat on the other hand should be limited to less than 10% of total calories consumed. Research suggests that eating up to 15% of calories from polyunsaturated fats is protective of heart health.

So, what does this translate into? Someone who’s eating 1800 calories per day would need 60g of fat with no more than 20 grams coming from Saturated fat, and up to 30 grams coming from polyunsaturated fats.

How to get it in my diet?

Choose fat from unsaturated sources. Include plant-sources of protein in your diet. Choose animal-based protein sources that are lower in saturated fat and cholesterol. Read food labels and avoid trans fats! As a note, even if a label says “0 g trans-fat” you still need to check the ingredients. If you see an ingredient that is listed as “partially hydrogenated” the product contains trans fats. The FDA allows manufacturers to list 0g trans fats if a product has a level that is below a certain threshold.

Breakfast – avocado toast made with ½ an avocado = 12 g

Lunch – roasted butternut squash salad with walnuts and goat cheese = 16 g

Dinner – baked salmon = 12 g

Daily Total = 40 g (mostly from mono- and polyunsaturated sources!)

References

American Heart Association. (2021, November). Dietary Fats. Retrieved from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/dietary-fats

Harvard T.H. Chan School of Public Health. (n.d.). Types of Fats. Retrieved from https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/

Michels, A. J. (2011, September). Skin Health. Oregon State University. Retrieved from https://lpi.oregonstate.edu/mic/health-disease/skin-health

Wolters, M., Ahrens, J., Romani-Perez, M., Watkins, C., Sanz, Y., Benitez-Paez, A.,… Gunther, K. (2019). Dietary fat, the gut microbiota, and metabolic health – A systematic review conducted within the MyNewGut project. Clin Nutr, 38(6), 2504-2520. doi:10.1016/j.clnu.2018.12.024