Is baking with flaxseeds dangerous? An excellent question!
Five and a half years ago, I wrote a blog post answering this question. Well, sort of. I initially wrote the post when I was in the throes of nutrition school. I was totally overwhelmed by new, exciting and terrifying information, and overly enthusiastic to share it with others. I was afraid that baking with flaxseeds would oxidize them and create dangerous free radicals.
Now, years later, I’ve learned to distinguish between the bad, the not-so-bad, the okay, the good and the freaking great. I strive to be mindful and balanced when it comes to what I eat, but also temper my passion and Type A extreme tendencies with realism and practicality.
Soon after I published my thoughts on baking with flaxseeds, a number of readers directed me to some scientific studies that show ground flaxseed remains stable in baking. After being armed with new information, and also through my own research, I’ve concluded that ground flaxseed is safe for baking and I’d like to outline a few key studies that illustrate this. (If you’re not into the science of baking with flax seed, I invite you to drool over chocolate brownies.)
Let’s take a look at some of the evidence.
1. Study: Bioavailability of alpha-linolenic acid in subjects after ingestion of three different forms of flaxseed
In a nutshell: In this study, people were separated into three groups and given different types of muffins: one group ate muffins with whole flaxseed, one group had milled (ground) flaxseed and the third consumed muffins with flaxseed oil. Each group ate their muffins every day for 3 months. After analyzing blood samples, researchers concluded that baking didn’t affect the integrity of flaxseed’s alpha-linoleic acid (ALA), and omega-3 fat. The flaxseed oil group had the highest ALA levels, followed by the milled flaxseed, while the whole flaxseed participants didn’t have an appreciable difference in their ALA levels.
Another thing the researchers learned is that flaxseed in baking didn’t change cholesterol or triglyceride levels, or increase levels of EPA or DHA. (EPA and DHA are long-chain omega-3s that are especially anti-inflammatory; DHA is exceptionally awesome for the eyes and brain.)
2. Study: Effect of processing and storage on the stability of flaxseed lignan added to bakery products
In a nutshell: This study looked at the processing and storage of a flaxseed compound called secoisolariciresinol diglucoside (SDG) baked into doughs, breads, buns and muffins. The baked goodies were tested right after baking, a week later, a month later and two months later. In all of the products, the SDG (the flax compound) was able to stand up to normal oven temperatures.
3. Study: Effect of thermal heating on some lignans in flax seeds, sesame seeds and rye
In a nutshell: Researchers tested unheated and heated sesame seeds, sesame products, rye grains, rye flour, rye bread and flax seeds. At 100 degrees celsius, the lignans were not affected in the dry products – in fact, the heat helped extract the compounds, while the products with moisture began experiencing degradation. Interestingly, at 250 degrees celsius the lignans in sesame and rye had deteriorated but not the lignans in flaxseeds.
4. Study: Processing and cooking effects on lipid content and stability of alpha-linolenic acid in spaghetti containing ground flaxseed
In a nutshell: When researchers examined ground flaxseed incorporated into spaghetti, they found that the alpha-linoleic acid (ALA) stayed stable.
5. Study: Nutritional characterization and oxidative stability of α- Linolenic acid in bread containing roasted ground flaxseed
In a nutshell: In this one, researchers toasted brown flaxseed in a pan and then baked into bread with wheat flour. The roasted flaxseed bread was higher in fibre and lower on the GI scale than the control bread, but protein digestibility decreased. Scientists also discovered that after 2 days of storing the bread there was a “significant and gradual increase in peroxide value,” meaning some oxidation or rancidity had occurred. Overall, the researchers concluded that the flaxseed can improve the nutritional properties of bread, though they did emphasize that the biological effects of baking with flaxseed in the breads on humans would need further study in clinical trials.
6. Study: Incorporation of ground flaxseed into bakery products and its effect on sensory and nutritional characteristics – a pilot study
In a nutshell: The main focus of this study was to evaluate the sensory properties (tenderness, colour, chewyness, dryness, etc.) of breads and muffins that were baked with varying amounts of ground flaxseed. The baked goods were sampled and judged by a panel of study participants (they liked the 30% flaxseed bread and 50% flaxseed muffins the most).
From a nutritional perspective, there was a 15-fold increase in ALA in the flaxseed bread, and both breads and muffins contained increased fibre, potassium and protein (however, given the roasted flaxseed study mentioned in #5 I wonder how digestible that protein is?).
7. Study: Effect of processing and storage on the stability of flaxseed lignan added to dairy products
In a nutshell: This study investigated the stability of the flaxseed compound secoisolariciresinol diglucoside (SDG) once it was added to milk and then used to make a variety of dairy products. The milk was heated to varying temperatures, from 72 degrees celsius in pasteurized cheese, to 80 degrees in bottled whey drinks, to 90 degrees in yogurt. Researchers found that the SDG remained stable throughout heating and fermentation, and deemed it a good supplement for dairy products.
8. Study: A lignan complex isolated from flaxseed does not affect plasma lipid concentrations or antioxidant capacity in healthy postmenopausal women
In a nutshell: Postmenopausal women in Copenhagen ate a daily muffin, either with or without SDG, for six weeks. After analyzing blood samples, researchers determined that the SDG didn’t impact oxidation or affect the antioxidant capacity of the women. Blood levels of total cholesterol, LDL, HDL and triglycerides were not affected by baking with flaxseeds.
Conclusion: Overall, after reading the above studies and others, I think it’s safe to say that baking with flaxseed isn’t going to cause you any harm.
Another thing I found interesting after reading more about baking with flaxseeds is it doesn’t cause any improvements in cholesterol or triglycerides. This doesn’t mean that flax seeds won’t help reduce cholesterol or triglycerides – research indicates it does – but baked goodies aren’t the way to do it.
Finally, while the studies didn’t identify the ingredient list of the muffins, breads, buns and other pastries they baked with flaxseeds in these studies, I speculate they weren’t the clean, whole food, real-ingredient baked goods that can help support our overall health. I recognize that gluten-free, vegan baked goods are still a treat, but if I’m going to be enjoying a treat, I want to pack as much nutrition into it as I possibly can.
So if I baked flaxseeds into these gluten-free blueberry sage muffins, these prune chocolate brownies or these oatmeal almond breakfast cookies, I wonder if the flax would increase their health properties more than the flax did for the baked goods used in the studies?
Someone needs to do a study on that!