Friday, May 11, 2012

Nutrition ABCs...F is for Fat (Part Two)

My first post on fat described what fat actually is and why we need it. Today, let's talk practicalities - which fats you want more of and what food choices you can make to get you there. As promised, here are the good, the bad and the ugly - where fats are concerned.

Good Fats

Mono-unsaturated fats

Mono-unsaturated fats are found in most plant-based oils such as extra virgin olive oil, nuts, seeds and avocados. They do not increase your risk of disease although eating too much of them, like any fat, might add a little padding to your bottom line. Replacing saturated fats or processed carbohydrates with mono-unsaturated fats can help lower cholesterol and risk of heart disease. This type of fat is the mainstay of your healthy fat menu.

What does this mean for you? Use extra-virgin olive oil as your main culinary fat. Don't pour with abandon - you really only need about 1/2 - 1 tsp of oil per person when you cook. Enjoy avocado, raw nuts, seeds and nut butters more often as these whole food sources of fat come complexed with many other nutrients like fibre.

Poly-unsaturated fats

Poly-unsaturated fats are also found in plant-based oils, usually the nuts and seeds. Soy beans, dark green leafy veggies, algae and cold water, oily fish are also rich in poly-unsaturated fats. There are many different poly-unsaturated fatty acids but the ones with all the hoopla are the omega 3s and omega 6s. Essentially, they are twins - one is kind of evil, one is nicer. Both are necessary to your health. It is when these two are out of balance that our health suffers. Here's why:

Omega 3 fatty acids are precursors for molecules that are generally anti-inflammatory. Omega 6 fatty acids, with few exceptions, are precursors for molecules that are pro-inflammatory. The jury is still out on the "perfect" ratio of omega 3s to omega 6s. However, it should look a lot closer to 1:2 or 1:4 rather than the 1:10+ typically seen in the standard American diet. How did this come to be? Well, you see the list above of omega 3 food sources? Not exactly on the menu at Taco Bell. These are very healthy foods that just aren't that common for many people. What is common is fast food, "convenience" foods and tons of processed flour and sugar-rich baked goods that also feature tons of cheap, omega 6-laden fat like soy and corn oil.

What does this mean for you? Eat fewer processed and fast foods; rid your cabinet of margarine and cooking oils (except olive oil) to reduce your intake of omega 6s. If you are allergic to dairy or vegan, consider using an organic coconut oil-based spread but use it sparingly. Increase your intake of oily fish (if you eat fish) like herring, sablefish and salmon; eat more flax, hemp, pumpkin and chia seeds and dark green leafy veg to increase your omega 3 intake. 

If you choose to supplement, don't pay for a 3-6-9 supplement; you get plenty of 6 (most foods) and 9 (olive oil!) already. Don't buy into the marketing. Look for EPA and DHA in your supplement, as these are the omega 3 forms that are most rigorously tested in a clinical setting. I like the new algae-based supplements from a sustainability standpoint. They don't contain EPA but the body can inter-convert DHA to EPA and they usually contain oils that can theoretically increase EPA in the body.

Less Good...and sometimes bad

Saturated Fats

Saturated fats come mostly from meat and dairy and can also be found in tropical oils - such as palm and coconut. We used to think that saturated fat was terrible for you and then the team at Harvard School of Public Health published a review article that challenged this thinking. We come back to these kinds of contradictions time and time again in nutrition science. Why? In my opinion, it is because we don't eat tubs of saturated fat. We eat food. And each food is a complex substance filled with different nutrients and co-factors that we still don't fully understand. And we eat these foods in the context of diets and lifestyles that change their impact. 

So what is the current thinking on saturated fat? Generally speaking, it falls into the "a little is fine, too much is bad" category. We need some saturated fat in our diets. However, the foods and eating patterns associated with a higher intake of saturated fat (meat, dairy, fast food...) are the same ones that will point us in the direction of less healthy choices and risk for obesity and chronic disease. So look to minimize your intake of saturated fats. And what about coconut oil? Don't believe the hype - it will not cure your cancer or help you to lose 10 lbs without dieting. However, the "new" coconut oil is far less processed than the stuff that used to fill processed food in the eighties. It appears that plant-based saturated fats won't raise blood cholesterol as much as animal-based ones. But they still can't touch the health benefits of mono-unsaturated or omega 3 fats. 

What does this mean for you? Eat a modest amount of lean meats such as poultry and seafood and just a bit of red meat (if you eat meat!). Remember that meat servings don't need to be bigger than a deck of cards. Skim the fat from milk and yogurt; eat smaller portions of cheese - don't just slather everything with it. Save good quality (preferably organic) butter for occasional baking. Enjoy good quality coconut oil in recipes if you like but don't start eating it with abandon. Saturated fats are not something you need to actively seek out...there is a small amount of saturated fat in almost every other fat source we consume.

Down-Right Ugly

Industrial trans fats

A trans fat is made in two ways: the first, due to the miracle of a cow's many stomachs; the second, as a marvel of modern science. The first way does not appear to cause any harm and may even have some benefit. The second needs to be eradicated from our food supply. It is highly inflammatory; it raises our bad cholesterol and even worse...lowers our good cholesterol. It exists for the sole purpose of extending the shelf life (and profit margins) of foods we shouldn't be eating in the first place. I won't bother with much of a debate. These things are terrible.

What does this mean for you? Beware the "trans fat free" food. If a food contains less than 0.5 grams of trans fat per serving, it can be labelled trans fat free. However, if you eat 6 cookies with 0.3 grams of trans fats each, you have just consumed 1.8 grams. Doesn't sound like much, but it is essentially your "safe" daily limit for trans fats. Instead, avoid fried foods in restaurants and fast food outlets as these are most at risk for being filled with trans fats. Ditto for cheap baked goods like cookies, muffins and pastries. Read ingredients lists: if you see the words shortening, margarine or hydrogenated fat - take a pass. 

Have a question about fats? Let me know!

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