Vegan Nutrition with Brenda Davis
Brenda Davis is a registered dietitian in private practice. She is the past Chair of the Vegetarian Nutrition Dietetic Practice Group of the American Dietetic Association. Brenda is co-author of the international best seller, Becoming Vegetarian, and highly acclaimed Becoming Vegan. Brenda is an internationally recognized speaker. She has worked as a public health nutritionist, a clinical nutrition specialist, nutrition consultant and academic nutrition instructor.
Question: I'm very new to veganism and searching around gives contradictory information. There are doctors who say veganism provides everything necessary and others who say it doesn't. My specific question is: can a vegan process enough DHA? Opinions seem very divided?
Answer: Good question. Wish I could give you the "final answer". Unfortunately, at this point, we aren't really sure. What we do know is that vegans can process DHA, but whether or not the amount they process is optimal for human health is the big question. Vegans generally have significantly lower levels of DHA than nonvegetarians (well under half in most cases), and while dietary modification can improve DHA levels, it doesn't bring it up to nonvegetarian levels unless a direct source of DHA is consumed. The actual conversion rate from LNA to DHA is approximately 2-5% (or less). To maximize conversion of DHA:
- Reduce intake of omega-6 fatty acids (these come mainly from processed foods and omega-6-rich oils such as sunflower oil, safflower oil, corn oil, soy oil and grapeseed oil).
- Limit intake of saturated fats and trans fatty acids (these reduce conversion).
- Make most of your fat intake monounsaturated fats (olives, olive oil, canola oil, avocados, nuts and nut oils).
- Include sufficient omega-3 fatty acids in the daily diet (flaxseeds, flaxseed oil, henpseed and hempseed oil, canola oil, walnuts, green leafy vegetables). For most adults 3-4 grams per day is a reasonable intake.
- Eat a nutritious diet - poor intakes of energy, protein and certain vitamins and minerals can reduce conversion.
For anyone striving to maximize DHA status (e.g. pregnant and lactating women), I would strongly recommend a DHA supplement of 100-300 mg/day. There are a few plant-source (microalgae-based) DHA supplements available, although most come in gel caps. Keep your eyes open - there will be more DHA choices available soon.