Friday, April 5, 2013

The importance of fat in a vegetarian diet

If you don't eat fatty fish two times a week, then how do you get your omega-3?

I had to write a report for university about the importance of fat in a vegetarian diet. It made me see fat in a whole new light.

Dietary fat is essential. It helps the body absorb nutrients and helps perform functions at the basic cell level -- and our body does this naturally, without us being conscious of it. However, if the body is not getting enough fat, things can go array, especially for vegetarians.

A low fat vegetarian diet can mean that we don't absorb all the essential nutrients that our body needs in order to function, as shown in the article "Mineral utilization of vegetarians: impact of variation in fat intake:" "in studies carried out at the University of Nebraska using healthy human subjects, low-fat diets were found to inhibit the absorption of iron, zinc, manganese, and calcium" (Kies, C V, 1988). 

On the other hand, too much unhealthy fat, like in the form of trans fat, can mean that our body does not convert fats into usable energy, and all of this can lead to all kinds of health problems.  In the article found in the American Journal of Clinical Nutrtion "Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications," the writers Brenda C. Davis and 
Penny M. Kris-Etherton warn that an unhealthy vegetarian diet can create havoc in the body: 

"First, it is important to ensure that the diet is nutritionally adequate, as poorly designed diets can impair the conversion process. Insufficient energy or protein decreases the activity of conversion enzymes, as can deficiencies of pyridoxine, biotin, calcium, copper, magnesium, and zinc. Excessive intakes of trans fatty acids can also depress conversion enzymes"

There are 4 main types of fat: trans fat, saturated fat, monounsaturated fat and polyunsaturated fat.

Trans fats and saturated fats are bad for you and can lead to an increased LDL cholesterol -- the "bad" cholesterol that can clog your arteries. Therefore, these fats should be avoided.

Some foods high in trans fat:
Fried food
Dairy products
and hidden in many processed foods

Some foods high in saturated fat:
Dairy products

HDL (good) VS.  LDL (bad)
Monounsaturated fat and polyunsaturated fat are the good fats that raise HDL cholesterol. HDL cholesterol helps fight the bad LDL cholesterol and keeps you healthy. Therefore, these fats should be consumed well.

Monounsaturated fat basically increases HDL cholesterol, therefore it's a good fat to be consuming.
These are some of the foods high in monounsaturated fats:
Canola oil (rapeseed oil)
Olive oil

Polyunsaturated fat is an essential fatty acid that the body does not produce and therefore must obtain from food. There are two types of polyunsaturated fats - Omega-6 (LA) and Omega-3 (ALA). When these fats are ingested, the body has to convert them in order to use them. Omega-6 is not difficult for the body to convert to AA. However, it is complicated for the body to convert omega-3 ALA into EPA and DHA because it needs "conversion enzymes" in order to do so. Direct forms of EPA and DHA are found in fish and seaweed. That sounds great, except that most vegetarians are not eating nearly enough seaweed to fulfill the EPA and DHA needs.

EPA and DHA (Omega-3) are needed for:
- cell membrane function
- proper development and function of the brain and nervous system
- protection against inflammation and diseases.

Foods high in omega-6 fatty acids:
Canola oil (rapeseed oil)
Corn oil
Soy oil
Sesame seeds
Sesame oil

Remember that the body needs "conversion enzymes" in order to convert ALA into EPA and DHA.
Foods high in omega-3 ALA:
Flax seeds
Flax oil
Canola oil (rapeseed oil)

Foods high in omega-3 EPA and DHA (direct source):

We need to include monounsaturated and polyunsaturated fats in our diet every day. They help maintain good health and keep diseases at bay and help us absorb important nutrients. Vegetarians should not be stingy about incorporating a healthy amount of these good fats in their diet because they help absorb iron, among other nutrients. 

As for polyunsaturated fats, it is recommended that women who are looking to become pregnant, are pregnant or nursing, or those with reduced immune system, should find direct sources of omega-3 -- EPA and DHA, either by consuming large amounts of seaweed (note that not all seaweed has omega-3;  and some seaweed might be contaminated with arsenic) or taking a seaweed supplement.  

For the rest of us, eating a healthy diet with sufficient fat, and not too much alcohol, can still convert ALA into EPA and DHA. Studies have shown that seaweed is just as good of an omega-3 source as fatty fish. More information can be found in the article "Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications" by Brenda C. Davis and Penny M. Kris-Etherton. 

It still means that moderation is key. Eating too much fat and not exercising daily can make you fat. By eating nuts and seeds, which are high in healthy fats, we can avoid over-consumption and get the freshest form of fat. Also, it goes without saying that saturated and trans fats should be avoided, if possible.

About 35 total energy percent should come from fat, while 15 energy percent from protein, and about 50-55 energy percent from carbohydrates. That 35 energy percent of fat is split into:

10-15 E% monounsaturated fatty acids
5-10 E% polyunsaturated fatty acids
1 E% omega-3 fatty acids


Davis, Brenda, C, och Kris-Etherton, Penny, M, (2003). Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications. The American Society for Clinical Nutrition, Volume 78, Issue 3 Suppl, p. 640S. From the database AJCN with Full Text:

Kies, Constance V, (1988). Mineral utilization of vegetarians: impact of variation in fat intake. The American Society for Clinical Nutrition, Volume 48, Issue 3 Suppl, p. 884. From the database AJCN with Full Text:

Livsmedelsverket: (Swedish Nutrition Board)

No comments:

Post a Comment


Related Posts Plugin for WordPress, Blogger...