WIL 5 Point Weekly Review #36
Blue light makes you fat, testosterone increases utilitarian decisions and more...
This is my free weekly newsletter covering 5 interesting points from the week. Subscribe (if you haven’t already) if you’d like to get it in your inbox each week!
1. Blue light is making you fat?
A 2024 prospective study out of UK found that higher exposure to blue light was associated with higher incidence of diabetes. The blue light story probably makes sense - you’re looking at too many screens at night, you’re staying up too late, your sleep worsens, your metabolic function worsens and then your risk for insulin resistance and diabetes goes up. Indeed, but another 2016 study on normal weight (human) adults noted some surprising acute effects of blue light. They found that within just 30 minutes of exposure to blue-enriched light, insulin resistance was “30% higher in the morning and 19% higher in the evening compared to dim light exposure.” Note that this was just 3 hours of exposure to blue light. Even in the morning, it worsened their body’s ability to control glucose levels.
They conclude that:
“…acute blue-enriched light exposure in the morning and the evening impacts glucose metabolism in healthy adults. Further research is required to determine the mechanism(s) by which this occurs, and how the mechanism(s) may be different at various times of day.”
Interestingly, as mentioned in my last WIL Weekly, red light decreases blood sugar, suggesting red light is a kind of “antidote” to these negative effects of blue light.
2. Does the sun really cause skin cancer?
Keeping in mind the first point, let’s consider the idea that the sun causes skin cancer.
・There is evidence suggests that vitamin D is protective against cancer.
・Vitamin D status also associates with cancer survival.
・Sun exposure is far superior to food for raising vitamin D levels.
・Note that getting sunlight through a glass window is a poor choice as it blocks UVB and hinders Vitamin D production.
・At least when it comes to prostate cancer, sun exposure over one’s lifetime reduces prostate cancer risk.
・Over the past century, work has largely migrated from outdoors to indoors. Thanks to digital attractions and air conditioning, people spending are spending way more time inside. Insufficient sun exposure has become a real public health problem.
・Yet, incidence of melanoma (a type of skin cancer) has increased 17-fold in men between 1950 and 2007.
・Long-term blue light exposure causes skin cancer in rodents.
・Blue light accelerates skin aging and induces hyperpigmentation.
・Freckles, a type of hyperpigmentation, is a “highly significant” risk factor for skin cancer.
・Red light is suggested to be a melanoma “therapeutic” as it inhibits melanoma proliferation.
・Red and near-infrared (NIR) light seem to protect against UV skin damage.
・It’s been suggested that the early morning sun, which has more (red and) infrared light may “precondition” the skin to better tolerate the mid-day sun which provides more intense UV rays.
・The sun emits blue and red + NIR light.
So is the sun bad for skin or is constant, excessive exposure to blue light relative to other wavelengths bad for the skin?
3. Testosterone increases utilitarian decisions
A study titled Decision making and testosterone: When the ends justify the means looked at 32 women’s testosterone levels and gave them a switch dilemma and a bridge dilemma:
The switch dilemma stated: ‘‘A trolley is running out of control down a track. In its path are five people who have been tied to the track. Fortunately, you can flip a switch, which will lead the trolley down a different track to safety. Unfortunately, there is a single person tied to that alternative track. Do you flip the switch?”
The foot- bridge dilemma stated: ‘‘As before, a trolley is hurtling down a track towards five people. You are on a bridge under which it will pass, and you can stop it by dropping a heavy weight in front of it. As it happens, there is a very heavy man next to you – your only way to stop the trolley is to push him over the bridge and onto the track, killing him to save five. Do you push the man?”
The women with the highest testosterone were most likely to say yes to both dilemmas. The study says:
"In other words, high-testosterone individuals appear willing to endorse a tough and costly decision, provided it promotes the greater good."
4. Seed Oils increase inflammation?
A meta-analysis of randomized controls from 2017 suggests that particularly high intakes of linoleic acid (key “bad” fatty acid in seed oils like canola, rapeseed, soybean oil, sunflower oil etc) increase CRP, a marker of inflammation.
Pooled effect size from 16 studies showed that the C-reactive protein (CRP) concentration was not significantly affected by increasing LA intake (SMD = 0.09, 95% CI: −0.05 to 0.24). However, subgroup and meta-regression analysis suggested that in subjects with a more profound increase of dietary LA intake, LA might increase the blood CRP level.
The conclusion first says linoleic acid doesn’t increase inflammatory markers …then they say it does increase CRP (a marker of inflammation) in the next sentence.
In conclusion, our meta-analysis provide evidence that higher dietary LA intake does not affect the blood concentrations of 11 inflammatory markers. However, in subjects with greater increase in LA intake, LA tends to increase the blood concentration of CRP.
5. Do Seed Oils give you a sunburn?
Dr. Cate Shanahan has an interesting post on her website titled Seed Oil Makes Sunburn Worse and Ages Your Skin there, she argues that seed oils increase the inflammation that occurs in your skin in response to UV exposure because these polyunsaturated fats in the seed oils get incorporated the skin’s cell membranes. Polyunsaturated fats are well known to oxidize much more easily than unsaturated fats and far more easily than saturated fats. She explains that most inflammation is driven by oxidative stress.
As far as I know, this seed oils cause sun burn idea is yet to be thoroughly proved in the literature. There are tons of anecdotes online of people cutting out seed oils and becoming better able to tan and tan without burning. What makes this very difficult to investigate is that it can take several years to substantially reduce the content of linoleic acid in your fat tissue (i.e. “detox” from vegetable oils). So, if you want to test this idea out for yourself, you can’t expect to immediately be sunburn resilient a week after cutting out all seed oils.
Not getting sun burned anymore was one of the main benefits of me cutting out seed oils years ago (barring here and there). I used to burn so quickly and so badly and my skin would peel etc, now it's not really a thing I think about ever.
I'd be interested in a study about boron and skin damage and cancer, because of it's ability to extend the half life of vitamin D.