A huge variety of diets and dietary advice is available today. Much of the advice can – at best – lead to confusion, but at worst, can lead to poor health.
However, most people feel extremely confident that their newly adopted diet will magically work wonders for them!
Rapid weight loss is often the aim of following a restricted diet, whatever the approach. At a worth of US$72 billion (2020 – 2023), the weight loss and diet control market isn’t disappearing anytime soon.
Unfortunately, few people know – or care - that rapid weight loss, and yo-yo dieting are both associated with increased mortality risks.
Diets, Politics and Religion
It can feel like you’re having a political or religious conversation when discussing Ketogenic, Paleolithic, Intermittent Fasting, or Vegan diets, with their adherents.
They all have a different focus on protein, fat, and carbohydrate consumption, and possibly some overlap, so a discussion can lead to serious differences of opinion with those committed to any of these approaches.
Unfortunately, there’s often little room for real science in these discussions, which can quickly become heated when opinions differ.
Furthermore, millions of people follow social media influencers who promote specific ways of eating, and often suggest specific purchases aligned with these diets.
They influence millions despite having little or no knowledge supported by evidence to uphold their beliefs, ideas, and opinions.
In the ‘olden days …’
Previously, the use of therapeutic diets, such as those that lower carbohydrate consumption, were strictly controlled by medical practitioners, with specific outcomes in mind, not only weight loss.
Today, these controls have been removed by the excess of information available on the internet.
This allows people to follow these approaches for longer than we have robust evidence to support their use for.
In addition, many of the research studies done to support the use of specific dietary approaches are funded by companies that sell products to support such dietary approaches, introducing confirmation bias.
What About ‘Brain Food’ in these dietary approaches?
Among this nutritional ‘noise,’ few people consider that their brain is the greediest organ they possess, and it has needs that nature stipulated millennia ago. It doesn’t care about the latest dietary trend, personal preference, opinion, or supplement.
The human brain is the most complex, sophisticated, and sensitive organ we posses. It is also the most flexible, or ‘neuroplastic,’ as it changes and adapts according to our environment.
This works both in our favour and against it, depending on the circumstances.
A vast network of intricately coordinated cells, chemicals, membranes and molecules combine to support this neuroplasticity.
All this potential and subsequent activity depends on specific nutrients to function optimally.
Research suggests that the potential for this adaptation, across the lifespan, is dependent on these required nutrients, which also impact cognitive function generally, along with mood, and how the brain ages.
The brain is therefore very sensitive to both nutrient excesses and deficiencies.
So, according to the current evidence, which diet is the best one for this precious and delicate organ?
Let’s start with the Ketogenic Diet
What is it?
The Ketogenic diet (also referred to simply as ‘Keto’) focuses on the consumption of high fat foods along with a severely restricted consumption of carbohydrates.
When the body (and brain) are deprived of carbohydrates, they will turn to using fat, in the form of ketones, as a source of fuel. This is called being in a state of ‘ketosis.’
Benefits?
We’ve known for over a hundred years that the ketogenic diet is effective in reducing epileptic seizures in children and some adults whose epilepsy is resistant to anti-epilepsy medication.
Some research suggests it can also be useful to stablise blood glucose in some adults with type 2 diabetes.
Challenges?
It is challenging to adhere to the Ketogenic diet due to its restrictive nature, and the high consumption of animal products, very low consumption of carbohydrate’s, including fiber rich fruits and vegetables.
This leads to an increase in the consumption of saturated fats, and possibly processed animal products, including foods with high levels of salt.
The result is a deficiency in specific vitamins, minerals, and fibre, all of which play critical roles in brain health.
Some research suggests this diet also negatively impacts the variety and activity of bacteria necessary for optimal gut health, which also impacts brain health.
Furthermore, the high reliance on protein poses a risk for kidney health, specifically for those who already have kidney disease.
Side effects of ketosis include nausea, constipation, vomiting, fatigue, acid reflux, kidney stones, elevated cholesterol and triglyceride levels, and atherosclerosis.
Eating a high percentage of non-organic animal products also introduces us to pesticides, as these toxins accumulate in the bodies of the animals exposed to them. This process is called bioaccumulation.
Many of these toxins are fat-soluble, which means they accumulate in our fatty tissues. This is a problem for our brain which is 60% fat at dry weight, and pesticides are linked to neurological challenges, including Parkinson’s disease.
Evidence?
The evidence does not support using a Ketogenic diet for long term weight loss, overall health, or neurological challenges (apart from intractable epilepsy), although some case studies and anecdotal evidence suggest it may be useful in some cases of Alzheimer’s disease.
Overall, using the ketogenic diet for anything other than short term weight loss isn’t supported by robust evidence. It is also likely to result in nutrient deficiencies that can impact brain function negatively over time.
The Paleolithic diet and the brain
What is it?
The Paleolithic diet (also known as ‘paleo’) focuses on eating unrefined, natural foods that have been around for millennia, hence the name.
Lean meat, fish, fruits, vegetables, nuts and seeds are included, while dairy, refined sugars, grains, legumes and processed foods are avoided.
People also refer to this type of eating as being low carbohydrate. In this respect it is similar to the Atkins diet which also focused on high protein, low carbohydrate eating.
In addition, this approach may naturally include the consumption of higher levels of saturated fats depending on what type of flesh is consumed.
An extreme version of this diet focuses on animal flesh and products and excludes plants entirely.
Benefits?
The focus on unprocessed and natural foods is of great advantage for our health generally and for the brain specifically.
The brain thrives on foods that haven’t passed through factories, where nutrients and fibre are removed, and additives are added.
Challenges?
Unfortunately, the idea that we would do well to return to an earlier time and eat the way some imagine we all ate as early humans isn’t based on solid evidence.
Furthermore, disease is not simply a result of factory food consumption and sedentary lifestyles. There are other factors that aren’t considered by this ‘return to early man’ approach to eating.
The traditional paleo diet includes daily servings of red meat, which although specific-nutrient dense, do lie at the top of the food chain, and likely contain antibiotics and pesticides if the animals are not organic and grass fed.
Again, the process of bioaccumulation is a threat to physical and mental health because of toxic accumulation generally, and specifically in sensitive brain tissue.
Although essential brain nutrients like B12, iron and zinc are plentiful in animal products, when they are consumed in excess they replace other plant-based foods that contain other brain nutrients which animal products are low in.
These include antioxidants, and other B vitamins and minerals such as magnesium, along with fibre, integral to gut and therefore brain health.
In addition, a deficiency in omega 3 fats, which are essential to brain development and function may be lacking.
Evidence?
Overall, despite an ongoing dispute about whether or not a paleo diet is what humans ate since the beginning of time, and despite anecdotal evidence, there is presently no evidence-based research to support this being the ideal diet for us generally, or for optimal brain function.
Some research suggests eating processed meat is a potential risk factor for dementia, although eating unprocessed red meat is associated with a protective effect.
In addition, a recent study that compared gut bacteria between paleo and non-paleo eaters found a compound in the gut of the paleo eaters, Trimethylamine N-oxide, that is linked to an increased risk of cardiovascular disease (CVD).
Specific, good bacteria strains were also lower in the paleo group, suggesting that other, long term health challenges may be present due to the restriction of fibre-filled carbohydrates and a possible lack of antioxidant rich foods.
However, all paleo followers do benefit from excluding refined carbohydrates, but may want to increase their consumption of leafy greens and cruciferous vegetables.
NOTE: The Whole30 diet has become popular over the past few years and is a more restricted version of the Paleo diet, but after 30 days, it becomes less so. It initially restricts anything that a ‘cave-man’ couldn’t hunt, including anything made using products that ‘Paleo’ endorses, such as high protein muffins etc.
In Part II we examine the Vegan Diet, Intermittent Fasting and the Mediterranean Diet, and summarise which is the best diet for optimal brain health.
Please check the ‘Become a Lighter Brighter You! in 90 Days’ Online Course if you want a focused, deep dive into nutrition and brain health where you will discover the facts behind feeding your brain optimally.