Doctor’s Tip: Good fats, bad fats
This is the final column in a series about the three macronutrients. The first column was about protein, and last week’s was about carbohydrates. Protein and carbs have four calories per gram, fat has nine. For optimal health we need to get at least 10 percent of our calories from fat. Current guidelines recommend somewhat more. But fat tastes good, and most Americans eat too much fat. More importantly, they chow down on the wrong kind of fats. Let’s discuss the different fats.
All meat and dairy products contain some trans fats. By adding hydrogen atoms to vegetable oils, trans fats can also be manufactured. These “partially hydrogenated vegetable oils” are solid at room temperature, add taste and a pleasing texture, and add shelf life to products that contain them. Manufactured trans fats are found in products such as deep-fried food, doughnuts, cakes, pie crusts, biscuits, frozen pizza, cookies, chips, crackers, microwave popcorn, non-dairy creamers, stick margarine and many spreads.
As Dr. Michael Greger says, trans fats don’t increase your shelf life. Trans fats lower HDL (good cholesterol) and raise total cholesterol, triglycerides and LDL (bad cholesterol), contributing to hardening of the arteries — the cause of heart attacks and strokes. Manufactured trans fats are now banned in Europe and North America, although in the U.S. “trans fat-free” can appear on food labels if there are up to 0.5 grams per serving, which can add up. It’s important that you check the ingredients on food labels and avoid products that contain “partially hydrogenated” soy, canola or other oil.
These fats are solid at room temperature and are found in all animal products, including meat and poultry, dairy and eggs. They are also found in coconut products, palm oil, and in vegetable oils including olive oil. Saturated fats increase production of LDL by the liver. There is a clear link between saturated fat intake and many chronic diseases we suffer and die from in Western societies, including obesity, diabetes, heart attacks, strokes, dementia and cancer. Several organizations, such as the World Health Organization and the U.S. Dietary Guidelines, recommend replacing saturated fats with polyunsaturated (plant) fats.
These fats are liquid at room temperature, and are found in olives, avocado, vegetable oils and some nuts and seeds. They became popular in 1990s after a study that suggested that people on the Mediterranean Diet — which includes olives and olive oil — were healthier than people on the standard American diet. Although replacing saturated fats with monounsaturated fats improves health, Dr. Esselstyn — one of two doctors who have proven that heart disease can be reversed by a plant-based, whole food diet with no salt, sugar or added oil — points out in his book “Prevent and Reverse Heart Disease” that “the medical literature is filled with evidence of the harmful effects of monounsaturated oil.” For optimal health, we should avoid added oil including olive oil — oil being a fat that contains 120 calories per tablespoon with few to no nutrients. We should also limit intake of olives and of avocado (up to ¼ avocado a day including what’s in guacamole is probably OK for people who aren’t trying to lose weight or reverse heart disease).
All vegetables contain these fats, which include the two essential fatty acids that our bodies can’t manufacture: the omega-6 fat linoleic acid and the omega-3 fat alpha-linolenic acid. These healthy fats are important for structure and function of cell membranes and are precursors to hormones. It’s important to have a balanced ratio of omega-6 to omega-3, but most Americans have too much omega-6 and too little omega-3, and this imbalance causes inflammation and contributes to depression, cancer, heart disease and diabetes. Whether you’re an omnivore, a vegan or a vegetarian, increase your omega-3 level by eating more walnuts, soy, flaxseeds, chia seeds, hemp seeds, beans, brussels sprouts, algae and seaweed. Fish also has omega-3 but is an animal protein (which has its own set of problems), contains cholesterol, and environmental toxins such as heavy metals and PCBs. In addition to a handful of walnuts and a tablespoonful of ground flaxseed every day, vegans should consider 500 mg. of algae-derived omega-3, available at City Market.
In the media and on the internet you will find recommendations that contradict some of those in this column. In large part this is because the meat and dairy industries try to muddy the waters of established science, and also often influence official dietary recommendations. An unbiased source is nutritionfacts.org.
Greg Feinsinger, M.D. is a retired family physician who has a nonprofit: Prevention and Treatment of Disease Through Nutrition. He gives a free presentation at 7 p.m. the first Monday of the month at the Third Street Center in Carbondale; is available by appointment for free consultations (379-5718); and conducts a shop-with-a-doc session at 10 a.m. the first Saturday of the month at Carbondale City Market.
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