Gary Brecka

Correct, and quickly too. The composition of your gut flora shifts within days when you change your diet, and shifts back as soon as you fall into your old pattern. This is one of the few things about gut bacteria that is firmly established.

This is an attractive summary of something that has not yet been established. That giving in to a craving frequently makes it harder to resist is recognisable and fits with what we know about habits. That sugar demonstrably damages the decision-making part of your brain has not been shown in humans and comes from animal studies.

That figure comes from nowhere. The commonly reported observation that sweetness tastes more intense after a period of reduced sugar intake is plausible, but that is a matter of taste adaptation and not the same as the recovery of dopamine receptors. In humans, receptor sensitivity has never been measured after ten days without sugar, so the timeframe is simply made up.

The claim that sugar engages the opioid system comes mainly from animal studies, where the effect is clear. In humans it has been demonstrated more indirectly, partly through the finding that a drug blocking opioid receptors reduces the preference for sweetness. The direction is correct, but the certainty goes beyond what has actually been measured in humans.

For many people, the sharpest period does indeed fall in the morning, but not immediately after waking. The first half hour to hour is characterised by sleep inertia, during which you react more slowly and make poorer decisions. Moreover, it depends on your chronotype: evening people peak hours later. 'Cognitive prime' is not a term used in the research literature.

The circadian rhythm is well established. The roughly ninety-minute rhythm is too, but only during sleep, where the succession of sleep stages follows that pattern. The idea that people are sharply focused in ninety-minute blocks during the day is an old hypothesis that has never been proven. How long someone can sustain attention varies from person to person and from task to task.

It is true that oak leaves contain gallic acid, ellagic acid, and tannins. How much of these actually ends up in the water when you brew them is unknown, and there is no research showing any health benefit. Moreover, high tannin levels can inhibit iron absorption.

These properties come from test-tube experiments using concentrated extracts, which tells us nothing about a cup of tea. The HIV claim is the most harmful: there is not a single human study to support it, while effective HIV-suppressing medications do exist.

Correct. Fibre slows gastric emptying and forms a layer through which glucose passes more slowly, and fat also slows gastric emptying. As a result, the same amount of carbohydrates produces a lower peak. This is one of the best-supported pieces of advice on blood sugar management.

Protein at breakfast does dampen the blood sugar spike and keeps you feeling full for longer; that is well established. The specifics are not. Where the figure of thirty grams comes from, why it has to be within an hour, and the claim that it prevents cravings later in the day are not supported by any evidence. A reasonable habit dressed up with an invented number.

That a craving subsides on its own is correct. An urge peaks and fades, usually within a few minutes, and waiting before acting is a well-established way of not giving in to it. The glass of water is not an active ingredient in that process; the waiting is. And claiming that ten minutes is always enough is stated more precisely than the evidence warrants.

The gut does indeed communicate with the brain via the vagus nerve; that is well established. That bacteria thriving on sugar influence your dopamine and serotonin levels through that pathway has not been demonstrated in humans. Ghrelin does not belong in this list in the first place, as it is produced by the stomach. Most of the evidence comes from germ-free mice, and that does not translate straightforwardly to humans.

In rats that binge on sugar, the number of dopamine receptors demonstrably decreases. In humans, that pattern has been observed in obesity, but it is impossible to separate what is caused by sugar from what is caused by excess weight itself. That the prefrontal cortex suffers as a result is a plausible but not yet proven next step.

Correct. Raw egg white contains avidin, which binds biotin so tightly that it can no longer be absorbed. Heating destroys the avidin. Added to this, the proteins in cooked egg white are far better digested than those in raw egg white, at around 90 percent versus 50 percent.

Two things go wrong here. Singlet oxygen is not a free radical, and it is not the substance that hydrogen gas acts on according to the research; that concerns hydroxyl radicals. Furthermore, virtually all the evidence comes from animal studies and small short-term trials. Whether hydrogen has any effect in humans is an open question, and inhaling it for four hours a day goes far beyond what can be concluded from that research.

Carotenoids are fat-soluble, so without fat in the same meal the intestine absorbs only a fraction of them. This has been measured repeatedly, including with salads with and without dressing. Milk fat works well for this purpose, but any source of fat does the same; olive oil or avocado works just as well.

The first part is correct: goat's, sheep's and buffalo milk contain no A1 beta-casein, so in that sense they are A2. They are not naturally homogenised, however. Goat's milk has smaller fat globules and lacks the substance that causes fat to cluster together, which means the cream rises more slowly. That is not the same as homogenisation, and in the case of buffalo milk it does not apply at all: buffalo milk is particularly high in fat and the cream separates quickly.

Insurers calculate life expectancy for groups, and that works: given a thousand people with the same profile, it is reasonably possible to predict how many will die per year. For a single individual, it does not work. The margin around such a prediction is years, not months. Anyone who claims to be able to pinpoint an individual's moment of death to within a month is confusing an average with an outcome.

Some studies observe a drop in cortisol levels after breathing exercises, others do not. The measurements vary, the sample sizes are small, and the measurements are almost always taken around the exercise itself. It is plausible that breathing promotes relaxation, but it has not been demonstrated that it durably lowers your cortisol.

Slow, controlled breathing increases the activity of the vagus nerve, which can be seen in a lower heart rate and greater heart rate variability. This effect occurs during the exercise and has been well measured. Box breathing is one of many effective forms, not the only one.

This is only correct when breathing slowly, and for a different reason than is usually cited. In a healthy adult, the blood is already about 97 percent saturated with oxygen, so breathing more adds nothing to that. What does play a role is carbon dioxide: slow breathing keeps carbon dioxide levels higher, which makes it easier for haemoglobin to release oxygen into the tissues. Breathing fast and deeply does exactly the opposite.

Breathing exercises reduce anxiety symptoms, though the effect is modest. Review studies find a small to moderate improvement compared to doing nothing. It is therefore a sensible habit, but not a treatment that resolves an anxiety disorder on its own.

Slow breathing increases heart rate variability, and this is one of the best-documented effects of breathing exercises. At around six breaths per minute, your heart rate synchronises with your breathing, causing variability to rise immediately. What is less clear is whether that gain persists during moments when you are not practising.

Cancer begins with damage to a cell's DNA. The altered metabolism seen in tumours is usually a consequence of that damage, not a cause. In a small group of tumours the fault does lie in a metabolic gene, as with IDH or SDH mutations, but that is the exception. The word every turns a partial story into a complete explanation.

Nutritional deficiencies are real and are genuinely overlooked at times: a deficiency of vitamin B12, iron or vitamin D causes symptoms that can easily be mistaken for something else. However, most chronic conditions do not stem from deficiencies, and the idea that doctors treat only the consequences is inaccurate: when investigating fatigue or low mood, blood tests for precisely those deficiencies are standard practice.

In rare cases this is correct: an adrenal tumour that produces catecholamines (phaeochromocytoma) causes episodes that resemble panic attacks. As a general explanation for anxiety symptoms, however, it does not hold up. Anxiety arises from an interplay of predisposition, experiences and circumstances, and cannot be reduced to measurable fluctuations in these substances.

There is no measurable catecholamine balance that can be restored to improve sleep. Dopamine, noradrenaline and adrenaline fluctuate throughout the day, and a blood or urine test for them says nothing about the quality of your sleep. Sleep problems are treated by addressing sleep behaviour and, where necessary, targeted investigation, not by adjusting these substances.

There is no diet or lifestyle method that cures cancer, natural or otherwise; this is a personal anecdote, not replicable evidence. Lifestyle does influence cancer risk (see our response), but anyone who delays or replaces treatment with a diet in hopes of a cure faces real danger. → Which lifestyle factors reduce your cancer risk the most?

Intriguing mouse research suggests that early memory problems are partly retrieval problems: the memory seems to still be there, but access to it falters. However, in advanced Alzheimer's, brain cells and networks are genuinely lost; as a general statement, this is stated too boldly.

Amyloid plaques are accumulations of a protein (amyloid beta), not stored sugar. A disrupted sugar metabolism can influence the disease process, but this picture of sugar being stored in synapses is factually incorrect.

An RF-182 receptor cannot be found in the scientific literature. That sugar activates the reward system with dopamine is correct in itself, but this specific mechanism cannot be verified.

Calcium balance does not work this way: hormones regulate the calcium level in the blood for the whole body, and bones serve as a reserve store in that process. There is no such thing as the brain itself withdrawing calcium from bones.

There are indications, mainly from animal studies, that insulin can be produced locally in the brain. But by far the most insulin comes from the pancreas; how important that local production is in humans remains an open question.

Insulin resistance in the brain plays a role in some Alzheimer's patients and the term 'type 3 diabetes' genuinely comes from research. But it is not a recognised diagnosis and as a complete explanation for Alzheimer's it is stated too boldly; people without blood sugar problems get the disease too.

With significant fluid loss through sport, heat or illness, electrolytes demonstrably help to retain fluid. But on an ordinary day with normal eating, adding extra minerals to your water makes little difference; your food already supplies them. → Do you really need electrolyte supplements?

The idea of depleted agricultural land is a persistent sales pitch: analyses find at most modest declines in minerals in crops, and a varied diet meets the needs of most people. Supplementation makes sense for a demonstrated deficiency, not as a standard measure for everyone. → Do you really need electrolyte supplements?

Amino acids are calories and activate exactly the systems that fasting shuts down: insulin and mTOR. Anyone fasting for autophagy or insulin rest therefore does break their fast with essential amino acids. Only someone looking purely at blood sugar will notice little effect.

Here too the direction is correct: screens just before bedtime are associated with shorter sleep in children. The exact percentage varies by study and depends on what is being watched; the figure is stated more confidently than the research warrants.

The direction is correct: screen use just before bedtime is associated with later sleep onset in children. But such a precise percentage comes from a single study; other research finds different numbers. As a hard general figure, this is false precision.

Correct: light in the evening demonstrably suppresses melatonin release, and blue light does so most strongly. One caveat: ordinary indoor lighting has this effect too; it is not unique to screens. → Does a blue-light filter on my phone really affect my sleep?

Light management demonstrably influences your internal clock, and bright cabin light at the wrong moment can worsen jet lag. However, whether a blue light filtering glasses on a plane makes a noticeable difference has barely been studied directly.

Your lymphatic system does not shut down when you sit, and your body does not stop detoxifying; your liver and kidneys do that continuously. It is true that movement supports lymph circulation, since it depends on muscle activity. The core message is fearmongering around a real but modest effect.

Your kidneys and intestines process roughly one liter per hour; drinking a very large amount at once therefore has little benefit and can even be harmful. However, sipping as a strict rule involving the lymphatic system is exaggerated; simply spreading your fluid intake throughout the day is sufficient. → How much water do I really need to drink per day?