Vegan for Life - Jack Norris [24]
• Eat a protein-rich diet by following the guidelines in Chapter 7.
• Include plenty of vegetables and fruits in your diet.
• Get adequate sun exposure to make vitamin D or take a supplement that provides 25 micrograms (1,000 IU) per day.
• Stay active and include weight-bearing exercise in your fitness routine.
• Avoid excess sodium.
CHAPTER 5
FATS
Making the Best Choices
Studies show that, on average, vegans consume a little less than 30 percent of their calories from fat. That’s a bit lower than the average for non-vegan Americans, but not by much. The big difference is in the type of fat that vegans consume since plant foods are much lower in saturated fat than meat, dairy, and eggs.
The term “fat” is a big category that includes a number of different fatty acids, two of which are essential to our diet. Actual requirements for essential fats are low, but there may be advantages to eating some fat-rich foods overall. In this chapter, we’ll look at three issues: the long-chain omega-3 fats, meeting essential fatty acid needs, and the question of how much fat vegans can safely consume.
LONG-CHAIN OMEGA 3 FATS
EPA and DHA are the “long-chain” omega-3 fatty acids that are found mainly in cold water fish. These fats are thought to be important for cardiovascular disease primarily because they reduce blood clotting and inflammation.1 Because DHA is found in nerve tissue, inadequate levels could also be linked to neurological problems such as dementia and depression.2,3
Since the long-chain omega-3 fats are found primarily in fish and to a much smaller extent in eggs, lacto-ovo vegetarians consume very little, and vegans generally have none in their diets (although some vegans may consume very small amounts of EPA from sea vegetables).4 Whether or not this matters is a big question in vegan nutrition.
Dietary Fats: Terms You Need to Know
The Essential Fatty Acids
Linoleic Acid (LA): An omega-6 fatty acid found in grains, seeds, nuts, and oils, especially safflower, sunflower, corn, and soy oil.
Alpha-Linolenic Acid (ALA): A short-chain omega-3 fatty acid found in flaxseeds, chia seeds, hemp seeds, walnuts, canola oil, and some soyfoods.
Long-Chain Omega-3 Fats
DHA (docosahexanoic acid): Found in fatty fish, some eggs, and algae. It can be manufactured in the body from ALA, but optimal conditions for conversion are not well-known.
EPA (eicosapentanoic acid): Found in fatty fish, sea vegetables, and algae. It can be manufactured in the body from ALA, and small amounts can be made from DHA.
Potential Benefits of DHA and EPA: The Science behind the Claims
A number of studies (and large reviews of studies) have suggested that omega-3 fats reduce the risk of heart disease, but others have found no benefit. There has been so much published on this subject that it makes it almost impossible to analyze the individual studies. We need to rely on systematic reviews and meta-analyses instead. But even the reviews have been conflicting; two large ones published in 2006 reached opposite conclusions. When research is this inconsistent, it probably indicates that the benefits are modest at best.
Although the omega-3 blood levels of vegetarians have been measured often enough to show that they are clearly lower than in fish-eaters, the actual effects of these lower levels aren’t clear. A 1999 study in Chile found that vegetarians had significantly more platelets (which are involved in blood clotting) and a shorter bleeding time than non-vegetarians. 5 This suggests greater blood-clotting activity, which could raise heart disease risk. But when the vegetarians were supplemented with EPA and DHA for eight weeks, the bleeding time stayed the same (although other factors changed).6
In a 1992 study in the United Kingdom, there were only small differences between vegetarians and non-vegetarians in factors that affect blood clotting, and bleeding times were similar.7
So, of two studies looking at these effects, vegetarians fared worse than meat-eaters in one but were largely the same in