Zaid K. Dahhaj Profile picture
Feb 10, 2023 12 tweets 4 min read Read on X
The Endothelium: How to keep your heart strong and avoid a heart attack

(One person dies every 34 seconds in the U.S. from cardiovascular disease)

THREAD
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A blood vessel is made of 3 layers:

1. Endothelium

2. Smooth muscle cells

3. Adventitia

This thread covers the first since it’s the most crucial part of blood vessel health
What does your endothelium do?

The endothelial layer is thin, yet very active and responsible for:

• making hormones
• allowing passage for chemicals
• maintaining blood vessel function
• creating nitric oxide
• preventing blood clots
• relaxing the arteries
•… twitter.com/i/web/status/1…
What causes damage to it?

All the classic risk factors:

1. Smoking
2. Chronically elevated blood sugar
3. Obesity
4. High blood pressure
5. Oxidized LDL
6. Consumption of vegetable oil
7. Chronic sleep deprivation
8. Elevated homocystine levels
9. Elevated hs-CRP particles… twitter.com/i/web/status/1…
ENDOTHELIAL DYSFUNCTION

The root cause of any cardiovascular event is endothelial dysfunction

It takes decades to go from early stage damage to an advanced stage

That’s why your lifestyle is important
NITRIC OXIDE (NO)

I’ve covered this in the past

Nitric oxide is extremely important to maintain blood vessel function

NO acts upon the smooth muscle, creating a relaxation effect on the artery through vasodilation

Read more below
PLATELET AGGREGATION

When the blood vessel is damaged from the above risk factors..

Platelets clump together and go to the sight of injury to repair damage

If that process remains chaotic over time, more inflammatory cells and cytokines add insult to injury

Guess what… twitter.com/i/web/status/1…
REDUCTION OF NITRIC OXIDE

All risk factors which cause damage to the endothelium reduce NO

This reduces vasodilation which increases pro-atherosclerotic activity

More specifically:

• Endothelin-1
• Thromboxane

We must raise NO by any means
Assessing endothelial function

This involves expert help, but it’s valuable for those who want to go deeper

Cue non-invasive assessments of vascular health

1. Flow-mediated dilatation (measures nitric oxide function)

2. Pulse wave analysis (reveals the stiffness of… twitter.com/i/web/status/1…
MICRO-VESSELS

These take up a larger surface area than the large vessels

Most dysfunction is going to occur with them rather than the latter

One technique to asses function:

Laser doppler imaging

Useful to determine microvascular endothelium health
Regardless of technical details

You must build your foundation

• Sleep
• Hydration
• Nutrition
• Movement/Training
• Supplementation

I’ll help you do this and set you up with everything you need for LIFE

Let’s talk: zaidkdahhaj.com/coaching
If you like this tweet, you will love my exclusive emails for my subscribers.

Join here: zaidkdahhaj.substack.com/?utm_source=su…

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More from @zaidkdahhaj

Jun 5
29 studies

300,000 people

No proof sunscreen prevents skin cancer

This thread will break down why the centralized paradigm on sunlight and sun “protection” via sunscreen is a house of cards Image
Cue the following bit of research

PMID: 29620003

This 2018 study looked at 29 papers with over 300,000 people and found no strong proof that sunscreen prevents skin cancer

Earlier studies hinted at a link, but the faded after the 1980s

In short:

Sunscreen doesn’t seem to raise or lower skin cancer risk for most peopleImage
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No single study currently outweighs the 29 study meta-analysis in terms of overall strength for evaluating the sunscreen/skin cancer relationship
Read 17 tweets
May 4
Could isolated blue light, especially at night, raise blood sugar and insulin independent of food?

The answer is a resounding yes

Exposure to isolated blue light can acutely affect glucose metabolism and insulin sensitivity, even in the absence of food intake

This is one of those points that reshapes your understanding of circadian biology, most notably the relationship between light and metabolic function

It points to both the power of full spectrum sunlight in its ability to reduce blood sugar (PMID: 38378043) and isolated blue light in its ability to destroy glucose metabolism (PMID: 27191727)

In this controlled study involving healthy adults, exposure to blue-enriched light (~ 468 nm) for three hours in the morning or evening led to increased insulin resistance compared to dim light conditions

Most importantly, evening exposure resulted in HIGHER peak glucose levels, indicating a diminished ability of insulin to regulate blood sugar effectively during that time

Animal studies show similar results (PMID: 31646762), but I’m solely interested in human beings

The implications of these on human beings is significant, to say the least

•••

Circadian Disruption Alters Glucose Control

Blue light stimulates melanopsin-containing ipRGCs in the eye, which influence the suprachiasmatic nucleus (SCN)

This, in turn, regulates:

• Insulin sensitivity in tissues
• Pancreatic beta cell function
• Hepatic glucose output

The implication is that isolated blue light disrupts this unfathomably complex system, causing insulin resistance and glucose spikes even without eating

•••

Isolated Blue Before Meals Could Worsen Postprandial Glucose

If isolated blue light already elevates glucose and suppresses insulin sensitivity before a meal, consuming carbohydrates soon after can cause:

• Higher blood glucose peaks

• Greater oxidative stress

• Increased long term risk for insulin resistance, diabetes, and obesity

The implication is that light environment is just as important as diet quality and timing in metabolic health (this is clear when you study the literature)

•••

Increased Risk for Metabolic Syndrome in Artificially Lit Environments

No surprise that elevated nighttime glucose, poor sleep quality through circulatory melatonin suppression, and circadian disruption skyrockets chronic disease risk

Think about your office, school, indoor gym, grocery store, the list goes on

•••

Diagnostic & Therapeutic Insight

This opens the door to use circadian principles and proper light exposure as a non-invasive intervention for type 2 diabetics, prevention of pre-diabetes, enhancing insulin sensitivity, and chronotherapy

•••

When blue light is received in isolation and outside of the circadian context, especially after nightfall, it destroys SCN signaling which impairs:

1. Normal glucose tolerance rhythms

2. Melatonin secretion, which has a regulatory role in insulin signaling

3. Coordination between central and peripheral clocks (pancreas, liver, muscle, adipose)

•••

The POMC system comes into play too

POMC neurons within the hypothalamus of the brain are key in energy and glucose regulation

POMC makes a-MSH in response to UV within the sun’s full spectrum, which activates MC4R (melanocortin-4 receptor).. regulating satiety, sympathetic tone, insulin sensitivity, and gluconeogenesis

Mistimed light exposure alters SCN signaling to the hypothalamus

This blunts POMC activation or desynchronizes it from feeding rhythms

Downstream effects include altered MC4R signaling, disrupted glucose utilization + insulin sensitivity

Increased sympathetic tone → cortisol elevation → worsened glucose regulation

Continued belowImage
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Hormonal and neuroendocrine mediators play a key role here as well

Isolated blue suppresses SCN-driven melatonin, disrupting nighttime insulin timing, increasing peripheral insulin resistance, and flattening leptin rhythms.. all undermining metabolic stability
It also disrupts cortisol’s natural rhythm, causing an abnormal rise that drives blood glucose up through increased gluconeogenesis, insulin resistance, and elevated free fatty acids

Blue light-induced circadian disruption alters SCN-driven POMC processing, leading to mistimed ACTH and cortisol release, impaired CLIP signaling, and ultimately metabolic dysfunction
Read 7 tweets
Apr 3
The skin is a circadian organ

This fact throws the conventional narrative that unfiltered full spectrum sunlight inherently causes skin damage or cancer out the window

Here’s the proof: Image
The skin is a highly dynamic circadian organ, with its layers (epidermis, dermis, and hypodermis) each possessing peripheral clocks that interact with the body’s central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus

Skin, eyes, and brain are made of the same tissue when you’re an embryo (neuroectoderm)Image
These circadian skin clocks regulate a wide array of processes, including:

1. Melanin production
2. Cellular proliferation
3. Mitochondrial function
4. Repair mechanisms

All of the above and more are optimized according to the time of day via the light and dark cycle Image
Read 11 tweets
Mar 19
Here’s the circadian truth about the infamous truck driver case - the one centralized dermatologists love to weaponize against sunlight exposure: Image
This is the most misunderstood image in the health space when it comes to photoaging and skin cancer

It’s a case study that’s been twisted out of ignorance to fuel misinformation about sunlight Image
This unidentified 69 year old trucker spent 28 years on the road, and his face tells a story that centralized medicine fails to understand

The mainstream narrative is that the sun’s full spectrum itself caused his skin damage due to accumulated UV-A and UV-B exposure

Dermatologists point to this case as “proof” that sunlight is dangerous, using it to justify fear-based narratives around photoaging and skin cancerImage
Read 14 tweets
Mar 14
Circadian biology is the master regulator of all anti-cancer processes in the body

Through this, we understand that the demonization of sunlight, along with the lack of discussion about artificial light at night and circadian disruption, creates rising cancer rates

Here’s all the evidence you needImage
Virtually all major anti-cancer processes are either directly or indirectly controlled by circadian biology

Some processes might seem less dependent on circadian rhythms at first glance

But it inevitably comes full circle
Anti-cancer processes that are strongly circadian controlled include:

1. Apoptosis (cell death)
2. Autophagy (cellular cleanup)
3. DNA repair cycles
4. Immune surveillance
5. Antioxidant defense systems
6. Detoxification
7. Tumor suppressor genes (like p53)
8. Cell cycle checkpoints
9. Epigenetic regulation
10. Angiogenesis inhibition

All of these rise and fall rhythmically in sync with circadian biology (via the master clock in the SCN) or peripheral clocks in organs and cells
Read 23 tweets
Mar 3
Why full-spectrum sunlight and circadian alignment are the ultimate probiotics and gut healers

I’m using first principles circadian biology and gut physiology to show you the power of this work

Gut health transcends what you eat Image
We begin with the basics

The gastrointestinal system operates as a CIRCADIAN organ, which means it’s married to the light and dark cycle

Circadian biology regulates all aspects of gut physiology from motility to digestion to absorption to electrolyte balance

This is the bedrock of gut healthImage
1. Molecular clock mechanisms are found within the GI tract

The cells of the GI tract contain intrinsic molecular clocks composed of core clock genes such as CLOCK, BMAL1, PER, and CRY

These genes form transcriptional-translational feedback loops that generate rhythmic gene expression, influencing various GI functions

The rhythmic expression of these genes continues even without external cues, demonstrating that they are regulated by internal circadian mechanismsImage
Read 24 tweets

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