Dietary Fat & Cognitive Performance: Can a High-Fat Diet Be Bad for the Brain? | Metagenics | Blog23/8/2019  By Bronwyn Storoschuk, ND
As human life expectancy continues to increase, there is also an increased risk for cognitive impairment over the course of a longer life.1 Brain health and cognitive performance have received a lot of recent attention by researchers in order to understand, and develop, strategies that will reduce the risk for cognitive decline.2 Furthermore, greater importance is being placed on “healthspan” versus “lifespan,” and there is an increased demand to find ways to optimize overall health, including brain health and cognitive performance. In the past few years, more scientific interest on the influence of nutrition on brain health and function has emerged, especially as dietary fats have regained popularity among consumers.2 It has been well-documented that a ketogenic diet can have profound benefits on the brain and cognitive function; however, there is also evidence that suggests consuming a high-fat diet increases the risk of cognitive decline and may impair brain performance.2,3 To clear some of the confusion, it is important to differentiate between the different types of fats and the potential mechanisms that may explain impairment in cognitive function. As far back as 1990, animal studies showed that diets high in saturated fats caused significant impairments in learning and memory.4 The results from subsequent human studies showed similar findings. Research showed that high-fat diets, containing mostly omega-6 fatty acids and saturated fats, were associated with worse performance on cognitive tasks.5 In addition, diets that contained mostly saturated fats and transfats have been associated with an increased risk of brain disorders.6 It has also been determined that high-fat diets with elevated amounts of saturated fats and cholesterol may impair intellectual function, along with increased risk for other health concerns.7 As most Americans follow a “Standard American Diet,” which contains high amounts of omega-6 fatty acids, saturated fats, and transfats and low omega-3 fatty acids, it is not surprising that rates of cognitive decline are increasing in the US.2,8 In the United States, the major sources of saturated fats come from:9
Insulin resistance Although insulin is usually discussed in relation to carbohydrate intake, consumption of both saturated and trans fats have been studied to impair insulin sensitivity.12 In addition, data have shown diets high in saturated fats are associated with increased total body weight and abdominal obesity, which also contribute to insulin resistance.13 Overall, it has been found that cognitive performance declines as whole body insulin resistance increases.10 It is important to consider that the Standard American Diet is also comprised of large amounts of refined sugars and refined grains.2 Increased consumption of refined carbohydrates also leads to insulin resistance, the greatest effects of which are seen when high sugar intake is combined with excessive caloric intake—often found in conjunction with a high-fat diet.14 So although specific fats can induce insulin resistance, this combination is more detrimental and very common in the US population.2 Oxidative stress It has been observed that a high-fat diet, primarily composed of increased intakes of saturated fats and omega-6 fats, raises the levels of free radicals in tissues and the brain.11,15 Free radicals, or reactive oxygen species (ROS), contribute to oxidative stress and lead to cellular damage.16 Chronically high levels of oxidative stress are known to lead to cognitive decline.16 Research has shown that high-fat diet-induced oxidative stress also leads to reduced levels of brain-derived neurotrophic factor (BDNF), which plays an important role in the survival, and growth, of brain cells and may explain some of the impairment in cognitive performance.2,17 Interestingly, data from preclinical studies indicate vitamin E, a potent antioxidant, is associated with better cognitive performance.18,19 While these findings still need to be confirmed in human studies, this information suggests that oxidative stress is involved in cognitive impairment and may be an outcome of a high-fat diet.2 Moreover, high-fat diets, specifically the fats included in the Standard American Diet, commonly lack essential vitamins, minerals, and antioxidants, which may further limit the body’s ability to effectively combat the increased levels of oxidative stress resulting from this high-fat diet.20 Inflammation Studies show high-fat diets composed primarily of saturated fats and omega-6 fatty acids have been associated with significantly increased levels of inflammation both systemically and in the brain.2 The brain is very sensitive to levels of inflammation, as inflammatory mediators can easily cross the blood-brain barrier.2 In one animal study, a diet comprised of 60% saturated fat showed significantly increased levels of inflammatory mediators, reduced levels of brain-derived neurotrophic factors, and highly reactive cells in the brain. As inflammatory mediators increased, significant impairment in cognitive performance was observed.21 Fats & cognition It is clear that all fats are not created equally. For instance, a diet that is rich in omega-3 fatty acids has been found to support cognitive processes.11 Accordingly, diets high in omega-3 fatty acids are associated with enhanced memory and learning and may play a role in supporting healthy cognition.24-25 The most important omega-3 fatty acids for brain health are EPA and DHA.26 However, it can be challenging to get the appropriate intake of EPA and DHA by diet alone, especially when looking to enhance cognitive performance.26 Also, it is important to note that a low intake of total fat, less than 20% of caloric intake, has been studied to impair cognitive performance due to an inadequate intake of fat-soluble vitamins and essential fatty acids, all of which are necessary to support cognition and general health.10 Regardless of what diet is followed, when fat is consumed, it is very important to choose the right fats. Brain function is impacted by insulin resistance and is sensitive to oxidative stress and inflammation, all of which are increased on a high-fat diet.2 However, this does not mean that all types of fats are bad, as it is well-documented that omega-3 fatty acids support cognition, and fat, in general, is required for optimal brain health.24 This content is not intended as a substitute for professional medical advice, diagnosis, or treatment. Individuals should always consult with their healthcare professional for advice on medical issues. References:
Bronwyn Storoschuk, ND Bronwyn Storoschuk, ND is a board-certified naturopathic doctor trained at the Canadian College of Naturopathic Medicine. Prior to attaining her ND, Dr. Storoschuk completed her Bachelor of Science (Honours) in Kinesiology at Queen’s University in Kingston, Ontario. She currently works in private practice in Toronto, Ontario. One of her practices is located within an integrative fertility clinic, where she provides naturopathic care to individuals undergoing assisted reproductive technology (ART). Dr. Storoschuk integrates evidence-based medicine with the understanding of the body’s natural physiology and innate healing wisdom. She is passionate about empowering women to take control of their hormonal health and has a clinical focus in hormone balance, reproductive health, and fertility. Dr. Storoschuk is a paid consultant and guest writer for Metagenics.
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 by Ashley Jordan Ferira, PhD, RDN
Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome with significant social, communication and behavioral deficits and challenges.1 No cure exists for ASD, although early interventions (birth to 3 years) can yield developmental improvements.1 ASD impacts approximately 1 in 68 children in the US and is 4.5 times more common in boys (1 in 42) than girls (1 in 189).2 Vitamin D’s extraskeletal roles are numerous, including its role as a neurosteroid, impacting both brain development and connectivity, and likely synaptic plasticity as well.3 Vitamin D is also one of the most common micronutrient deficiencies. Previous research has revealed associations between gestational and early childhood vitamin D insufficiency and ASD.4 This suggests that hypovitaminosis D represents a modifiable risk factor for ASD.4 Furthermore, preliminary evidence demonstrates that gene variants related to vitamin D metabolism play a role in the pathophysiology of ASD.5 Robustly designed intervention trials have been scant. The first double-blind randomized controlled trial (RCT) utilizing vitamin D3 supplementation in children with ASD was published in The Journal of Child Psychology and Psychiatry in 2018.6 The study included 109 Egyptian children (85 boys; 24 girls) 3-10 years of age with confirmed ASD diagnosis. The children were randomized to receive vitamin D3drops (300 IU D3/kg/day; not to exceed 5,000 IU/day) or matching placebo drops daily for 4 months.6 Serum 25-hydroxyvitamin D (25[OH]D) levels were measured at baseline and 4-months. For ethical reasons, children who were identified to have vitamin D deficiency (25[OH]D <20ng/mL) were excluded from the study and administered vitamin D supplementation by the study authors.6 Autism symptoms were assessed using validated measures completed by two different psychologists and a senior psychiatrist.6 Four months of daily vitamin D3 supplementation at 300 IU/kg/day:6
Following 4 months of vitamin D3 supplementation, improvements (all p <0.05, most p <0.01; as compared to placebo) were demonstrated in many core manifestations of ASD, including:6
This rigorously designed RCT is the first of its kind to demonstrate safety and efficacy of vitamin D3supplementation in children with ASD.6 Two previous open-label vitamin D3 supplementation studies also demonstrated improvements in ASD symptoms.7-8 Wide-scale studies are warranted to continue to critically ascertain the effects of vitamin D on ASD. Why is this Clinically Relevant?
References
 Your Brain on DHA What is DHA? Docosahexaenoic acid (DHA) is a long-chain omega-3 fatty acid—the most abundant of all the fatty acids most commonly found in the brain and eyes. But like many essential nutrients, DHA’s importance is often overlooked, and many Americans fall short of the recommended daily allowance (RDA) outlined by the US Department of Health.1,2 With all the cognitive, and other, benefits DHA has to offer, ensuring you get enough through your daily dietary intake is truly a no-brainer. What are the benefits? Not only does DHA account for over 50 percent of omega-3 fatty acids in the brain, it also turns on your brain’s growth hormone, known as the brain-derived neurotrophic factor (BDNF). This helps support the survival and function of existing neurons and also encourages new neurons and synapses to grow.3,4 Unfortunately, BDNF circulation slows down with age and can be stunted by stress and other lifestyle factors.5 That’s why upping your DHA is so important. Although DHA is essential at every age, it’s especially crucial during three particular stages of life: Pregnancy DHA can be helpful for baby’s development as well as mom’s recovery. A study showed that mothers who supplemented with omega-3s during pregnancy saw their children score higher on intelligence tests due to enhanced cognitive performance.6 For some mothers, pregnancy also takes a temporary toll on cognitive functioning and memory. Colloquially, it’s called “baby brain,” and it’s likely due to hormonal changes and the stressors placed on a woman’s body to meet the increased needs of her unborn baby. According to research, pregnancy can sometimes shrink brain tissue and cause long-term changes to brain structure.7,8 Recovery from pregnancy-induced brain changes can take years, but increased dietary intake of DHA has been studied to help support the regrowth of cells along the way, as well as promote healthy brain development in the baby.9 Early childhood Babies and young children are growing every day, so it’s hard to understate the importance of DHA on brain development during this tender season of life.9 In fact, higher levels of DHA are associated with improved learning skills, while DHA deficiency in children has been linked to cognitive and learning disorders.10 That’s why making sure babies and toddlers get their fair share (500-700 mg daily)2 is a vital part of early brain development. Older adulthood The benefits of DHA are enormously promising for older adults looking to keep their brains sharp and healthy. In a study of over 1,500 men and women over the age of 65, those with the lowest levels of DHA had significantly lower brain volumes than those with higher DHA levels and scored lower on tests measuring both memory and abstract thinking skills.11 On the flip side, studies show higher levels of DHA in the body (1,600 mg RDA for those age 51 and older)2 have also been associated with a decreased risk for brain-related chronic illness.11,12 DHA & gray matter Our brains consist partly of something called “gray matter” (neural tissue that makes up a large amount of the central nervous system). Recent studies have supported a link between intelligence and the amount of gray matter in particular parts of the brain, which shrinks steadily in the years following adolescence. Though we naturally lose some brain volume over time, a higher intake of DHA is positively associated with gray matter volume and better cognitive function, even as we age.12 Where can I get it? You can get some of your DHA in foods like fatty fish (salmon, mackerel, tuna, herring, and sardines) as well as flaxseed, chia seeds, and walnuts. But for vegans and vegetarians, as well as those with nut allergies, obtaining DHA through diet alone can be a challenge. It’s also important to be mindful of how often you eat certain kinds of fish due to high mercury content. Supplementing with fish oils, a mainstay in many supplement regimens, can help fill in the gaps and give you the support you need for positive brain and cognitive development.1 There are many things to look out for when choosing a fish oil supplement, so keep these tips in mind while you shop. This content is not intended as a substitute for professional medical advice, diagnosis, or treatment. Individuals should always consult with their healthcare professional for advice on medical issues. References:
 There’s been plenty of buzz in recent years around the word “detox,” but your body is not the only thing that can be exposed to toxins. Your whole way of life might be exposing you to emotional toxicity, too.
We take the trash out from our homes on a regular basis. This allows us to discard what’s no longer useful and keep our living spaces clean and pleasant. If we neglect this responsibility, the consequences are hard to ignore: overflowing waste baskets, unpleasant odors, and possibly the invasion of pests! Unfortunately, emotional garbage is not so easy to detect. Bad habits, negative thoughts, toxic people, and unhealthy situations can overwhelm your personal space and accumulate clutter in your mind. Over time, both internal and external stressors cause your mental waste bin to become full. If you aren’t careful to filter out what you don’t need, that waste bin can overflow—and lead to a very unhealthy life! There are plenty of ways to minimize toxicity in your life. Consider these nine steps to start reducing stressors today. 1. Change your self-talk What are you thinking about right now? What did you think about when you first woke up? Believe it or not, your answers say a lot about you and your health.1 Your thought patterns are an integral part of your overall well being. Over time, repeated thought patterns influence behavior and beliefs.1 When your thoughts are mostly negative, it can feel like you’re stuck on a “not-so-merry”-go-round. Remind yourself, too, that you can’t always trust your own thoughts to be impartial. Sometimes you have to hit the pause button, take some deep breaths, and talk yourself off the ledge. And that’s okay. To break free from a negative thought spiral, try a relaxing, rejuvenating activity (e.g., read a book, practice yoga, tend to your garden, or listen to a favorite record) to lift your spirits and get your mind focused on something new. 2. Reevaluate your habits We all have bad habits. Some habits are relatively benign, like biting your nails or smacking your lips when you chew. But others, like hitting the snooze button, comparing yourself to other people, and picking fights with friends or partners, can actually be toxic to your well being. The first step toward improvement is self-awareness. To start, make a list of your habits and mark an X next to the not-so-good ones. As you build your self-discipline, remember to be patient with yourself. Studies say it can take about two months (not 21 days) to make or break a habit!2 3. Walk away from bad relationships Good friendships matter. In fact, research conducted over a ten-year period found that individuals with a stronger network of friends were 22% more likely to outlive their lonelier counterparts.3 But where good friendships can support your health, bad ones can do just the opposite. Pay attention to how you feel after hanging with certain people. If you’re always left feeling distressed in one way or another, it may be best to start distancing yourself from them. Don’t feel obligated to keep up friendships (or romantic partners) that cost you your mental and emotional sense of peace. 4. Disconnect from social media Social media is a double-edged sword. On one hand, it helps us stay connected with friends and family. On the other hand, it’s a hotbed of competition, comparison, and drama. Taking a break from social media can clear mental clutter and help you focus on the here and now. Evaluate your feelings after using Facebook, Instagram, or any other social network, then ask yourself why you feel this way. It’s a good idea to delete or un-follow highly negative people or those who stir up bad feelings whenever you visit their pages or see their posts. Doing this can spare you those negative emotions and allow you to focus your energy on more positive things. If nothing else, social media can be a real time killer. The time you save on scrolling could mean more time spent on hobbies or with loves ones. 5. Downsize your wardrobe Clothes are a necessity and a fun way to express personal style. Unfortunately, they are also an easy thing to hoard. Physical clutter can lead to mental clutter. If sartorial clutter has taken over your bedroom, you may be in need of a closet purge. The clothes you wear can affect your mood and your confidence, so it’s important that you feel good in them. Are any of your duds, well…a dud? Find out by doing a quick survey of every item in your wardrobe. Ask yourself: Would I feel good wearing this tomorrow or to an upcoming event? If the answer is no, it may be time to let it go. If you choose to donate, you can feel good knowing that your preloved apparel might work equally well for someone new. 6. Reorganize your work space While the importance of keeping a clean home seems like a no-brainer, your work area can be an easy thing to neglect—until you find it’s covered in “organized” piles of paper and old business cards. According to science, a clean, organized work space can boost productivity. In fact, a Harvard study found that students who worked in a tidier environment remained focused for 7 ½ minutes longer than messier students, who were more likely to experience frustration and weariness.4 Giving your desk or work space a weekly once-over means you are less likely to be invaded by dust bunnies and more likely to check items off your to-do list. 7. Turn off the TV It’s easier than ever to get hooked on television. The average American adult watches five hours of TV per day (wow!), and about 50 percent of Americans use some kind of streaming service—a number that’s been steadily rising.5 As statistics show, what we spend much of our free time doing is more passive than active, and that mindset may spill over into other areas of life. Although entertainment is not all bad, moderation may be the best approach to screen time. Increased television watching is associated with lower physical and mental vitality and may be linked to chronic health conditions.6,7 If this feels relevant for you, consider cutting your quality time with the tube by a small amount each day. Replace that time with a physical activity or creative hobby, which—according to research—can promote overall well being 8. 8. Reassess your diet The benefits of a balanced diet go beyond your physical body. It can also make you feel good mentally. Eating foods rich in vitamins, minerals, and antioxidants can protect your brain from oxidative stress, support brain function, and help stabilize your mood.9 There’s also plenty of evidence showing that when your body is low in certain essential nutrients, such as vitamin D and omega-3's, it can negatively impact mental health.10,11 If you’re stuck in a funk, your diet may be playing a role. To help combat those blues and support your health, start by incorporating wholesome snacks into your day, like nuts, fruit, or string cheese, and eat plenty of nutrient-dense greens whenever possible. Stock your fridge or pantry with things you enjoy that won’t make you feel guilty. And to set yourself up for success, rid your kitchen of sugary, greasy snack foods so you won’t be tempted to indulge. 9. Keep a journal Had a bad day? Feeling low but you don’t know why? Write about it! Reading what you wrote a few days later may give insights on things that can be reduced or eliminated to avoid future bad or unhappy days. Writing is one of the best ways to release bad feelings. Writing down your thoughts can feel just as good as venting to a friend. And because your thoughts are recorded in one place, it’s much easier to pick up on patterns in your thoughts and behavior—helping you prioritize problems, identify triggers, and work through anxious feelings.12 Anyone can do it! When life gets too complicated, well being silently suffers. And though we all have different thresholds for toxic overload, most of us could benefit from taking some steps to detox our lives as well. References:
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