TODAY'S AJENDA ISSUE #52

TODAY’S DOSE OF HONESTY

Why I’d Never Get a Gel Manicure 

It’s an essential part of my self-care routine: Getting my nails done. While I’m usually so busy that it’s not uncommon for my nails to pass their “expiration date,” I’m fortunate to live mostly in NYC, where you’ll find a nail salon on every block.

Every two weeks (okay, four), I’ll rush in, pick my color (I alternate between Essie Sheer Fantasy and Essie Wicked), and then plop down for 45 minutes of uninterrupted bliss. 

But the one thing that’s never part of this ritual? A gel manicure. 

I know, I know—if you love your gel, this is probably the absolute last thing you want to hear. But let me share what the dermatology literature says about the potential risks, and then you can decide for yourself. 

Ready? Here goes: 

1. UV Radiation Exposure

The most obvious one! Those purple lights used to make your manicure glossy emit UVA radiation, and that can come with consequences such as: 

• Increased Risk of Skin Cancer: UVA radiation plays a role in the pathogenesis (i.e., how a disease develops) of skin cancer. While the exposure from a single manicure is low, repeated exposure can increase the chances of squamous cell carcinoma—a common but treatable skin cancer—and melanoma, a more serious form of skin cancer. 

• Photoaging: UVA rays deeply penetrate the skin, which causes alterations to our dermal connective tissue. As a result? UVA exposure can lead to premature skin aging, known as photoaging. This process leads to wrinkles, pigmentation, and thinning skin. 

2. Allergic and Contact Dermatitis

Next is a risk I see little mention of: Allergic reactions—including ones that could even complicate future medical procedures. 

• Contact Dermatitis: The ingredients in gel polish, such as acrylates and methacrylates, can cause allergic contact dermatitis (Canadian Medical Association Journal, 2017). Symptoms may include redness, swelling, itching, burning, and blistering around the nail or fingertips. 

• Chronic Dermatitis: Once your body develops a reaction, it doesn’t just “go away.” These allergies can last a lifetime and extend beyond nail products, triggering reactions to things like dental adhesives or surgical glues, which can potentially complicate dental or orthopedic procedures down the road. 

3. Carcinogen Risk 

It’s not just the UVA radiation that can cause problems: It’s the possible inhalation of fumes and particulate matter from the gel polish itself: 

• Chemical Exposure: The ingredients inside gel polish—acrylate and methacrylate—are designated as probable human carcinogens (i.e., cancer-causing agents). While the exact dose needed to pose a serious risk hasn’t yet been determined, breathing in these fumes—as well as direct contact with the nail beds—is less than ideal. 

4. Nail Damage and Infection

The last reason defeats the whole point of getting a gel manicure—because, over time, it can make my nails look worse!

• Nail Weakening and Brittleness: Ever noticed how in gel manicures, they use an electric nail file to roughen the nail surface before applying the gel (to help it stick)? Unsurprisingly, this mechanical scraping—plus the acetone soaking—gives us the exact opposite of what we want (strong nails!). 

• Infection Risk: The downsides of these manicure instruments don’t stop there. If improperly sterilized, they can lead to bacterial or fungal infections. 

So…Should I Never Get a Gel Manicure Again? 

I’ll never tell you what to do (or not). I’m only here to give my opinion. 

But if I was your doctor? I’d say the risk of ruining your hands and endangering your health is definitely not worth the convenience of a gel manicure. 

If you don’t want to part ways with gel, be sure to watch your manicurist open clean instruments in front of you. The cleaner the instruments, the lower the chance of landing a bacterial or viral infection.

What I do? I get a regular manicure about twice a month. And at least once a year, I forgo the polish for 2-4 weeks to let my nail beds breathe (though, trust me, the bare toes are not a pretty sight!). And in the winter—AKA dry skin season—I’ll massage olive and tea tree oil into my nails. 

Now, if you excuse me, I have some bare toes to hide.

SYMPTOM SOLUTIONS

Can Drinking More Water Really Help You Lose Weight? 

“Exercise, exercise, exercise.” When it comes to burning more calories (officially known as increasing energy expenditure), exercise tends to steal the spotlight. But as we discussed in last week’s Ajenda, your body has other ways of torching calories—no gym required. 

One that I rarely see talked about? The thermic effect of food, which is the energy required for your body to digest what you eat and drink. The question becomes: Is there a way to strategically use this process to burn more calories? 

Short answer: Yes! And it can be as simple as reaching for your water bottle. Let me explain: 

How Drinking Water Leads to Burning Calories 

Out of all the foods and beverages we consume, water is the best one to leverage our body’s machine (to get more metabolic bang for your nutritional buck, so to speak). 

For starters, it’s known that water can activate the stretch receptors in your stomach, which triggers signals to your brain saying you’re ‘full.’ These satiety signals, driven by the hormone leptin, help regulate appetite and curb how much we eat.  

And the impact goes beyond just feeling full. A study by Popkin et al found that people who regularly drink water consume about 9% fewer calories per day—roughly 194 calories less—compared to those who don’t. That’s a big payoff for a small habit! 

Here’s some more science-backed evidence: Another study by Jeong (2018) in Clinical Nutrition Research discovered that non-obese people who drank as little as two cups of water (500 mL) consumed fewer calories than those who didn’t.

Woah. How Does This Work? 

Honestly? We still don’t fully understand how this process functions.  

One theory is that it’s linked to delayed gastric emptying—the same mechanism behind GLP-1 drugs such as Ozempic and Semaglutide. Another possible factor is the reduced secretion of motilin, a hormone that keeps the digestive tract moving.

So far, we’ve covered the what (water), why (it triggers stretch receptors in the stomach), and when (best before a meal). But what about the how? Specifically, does the temperature of the water matter? 

It turns out, interestingly, that research suggests it does!

The Optimal Water Temperature For Weight Loss 

When it comes to burning calories, colder is better! Let’s go back to a high school or college chemistry class to understand why. 

First is basic thermogenesis. When we consume something colder than our body temperature, we need energy to warm it up so it’s thermo-neutral (a fancy way of saying identical to our core body temperature). In other words: The colder something is, the more energy it requires. 

Now that we know that, what does the science literature say? 

A 2019 study by Fujihira et al. published in the European Journal of Nutrition found that in a group of 11 healthy young Japanese men, drinking 500 mL of water at 35.6°F (2°C for my non-American readers!) suppressed gastric contractions and reduced energy intake compared with those who consumed 500 mL of water at 98.6°F (37 °C) and 140°F (60 °C). 

And the effect was significant—those who drank cold water consumed 19% fewer calories than the 98.6°F group and 26% fewer than the 140°F group! 

Of course, more research on a large scale is needed—especially with women of all ages. But as of now, there’s sufficient published data for me to safely recommend drinking cold water before a meal. 

The extra calorie burn won’t likely be a huge amount, but over time, every little bit can add up. Ice ice, baby! ❄️

COMMUNITY

“Are NMN Supplements and NAD+ IVs Worth The Hype?” 

Thank you @lindaf and @brendalee40 for your questions! 

NAD+ IVs and NMN supplements are all the rage these days (cue the Instagram images from the Jenners and Kardashians boasting its benefits). 

But what exactly are NAD+ or NMN? And does the science back the hype? Let’s dive in! 

What Even Are These Things? 

NAD+ stands for nicotinamide adenine dinucleotide (try saying that five times fast) and is found in our cells.  It’s a molecule critical for energy metabolism, cellular signaling, and DNA repair, and it naturally declines with age.  

Recently, NAD+ supplements (e.g, nicotinamide riboside [NR] and nicotinamide mononucleotide [NMN]) have gained popularity for their potential anti-aging and health benefits.

• Quick Note: NMN and NR are precursors to NAD+, so you can think of them interchangeably, although there are some differences! 

How They Work (A Look Under The NAD+ and NVM Hood) 

NMN is a natural compound found in our cells that plays a key role in metabolism within the nucleus, mitochondria, and cytoplasm. 

Here’s where it gets interesting: Research has shown that “NMN has therapeutic effects towards a range of diseases, including age-induced type 2 diabetes, obesity, heart failure…as well as Alzheimer’s disease and other neurodegenerative disorders” (Journal of Advanced Research, 2022).*

^{*Paraphrased for clarity.} 

On the flip side, low NAD+ levels aren’t just associated with aging—they’re also linked to increased oxidative stress, brain fog, DNA damage, and even inflammaging (chronic inflammation that speeds up aging). 

The General Consensus 

While most of the research so far comes from cell (in vitro) and animal studies, the current evidence suggests that NAD+ precursors such as NMN may: 

• Boost Neuroprotection ➜ Evidence: Preclinical studies suggest NAD+ precursors can protect neurons, improve memory, and reduce pathology in Alzheimer's models (Hou et al., Aging Cell, 2018).

• Benefit Cardiovascular Function ➜ Evidence: Human trials report improved cardiovascular function with NAD+ supplementation (Wang et al., JACC: Basic to Translational Science, 2022).

• Improve Metabolism ➜ Evidence: Small human trials have shown improved insulin sensitivity and reduced markers of inflammation (Yoshino et al., Science, 2021).

This Sounds Promising. But Are There Any Downsides?

While NAD+ and NMN supplements show (very) exciting potential, there’s still a big gap in human research. Right now, there are little to no long-term, peer-reviewed studies confirming the ideal dose, long-term safety, or risks in humans. 

One of the best papers on this subject (available for you to read online for free right here!) was published in 2022 in the Journal of Advanced Research by Nadeeshani et al. The authors caution: 

^{*Paraphrased for clarity.} 

So, as much potential for positive effects as NMN and NAD+ show, there is also a possibility of negative side effects. 

The Potential Negative Side Effects 

These include:

1. Possible Cancer Risk Concerns

Since NAD+ fuels cell metabolism, some researchers worry that boosting NAD+ levels may unintentionally stimulate existing cancer cells. However, note that no clear evidence of this exists yet.

2. Cost and Quality Variability

Because NAD+ supplements are still so new, they can be expensive—and product quality or purity varies widely! (It’s not uncommon to find NAD+ IVs for nearly $600 a pop.)

3. Side Effects & Tolerability Issues

Some users report gastrointestinal symptoms, nausea, flushing, or skin problems such as itching and sweating. 

Bottom Line

The science isn’t fully there yet, especially when it comes to long-term safety and effects for women. While there’s reason to be optimistic, we still need larger human trials to be sure. 

In the meantime, no need to shell out hundreds of dollars for NAD+ IVs or NMN supplements. Foods like edamame, tomatoes, broccoli, cabbage, cucumber, and avocado provide key nutrients that support your body’s natural NAD+ production!

Thank you for reading! While you’re here, we’d love to ask you a quick question:

ABOUT DR. JEN

In her former roles as chief medical correspondent for ABC News and on-air cohost of “GMA3: What You Need to Know,” Dr. Jennifer Ashton—”Dr. Jen”—has shared the latest health news and information with millions of viewers nationwide. As an OB-GYN, nutritionist, and board-certified obesity medicine specialist, she is passionate about promoting optimal health for “the whole woman.” She has authored several books, including the national best-seller, The Self-Care Solution: A Year of Becoming Happier, Healthier & Fitter—One Month at a Time. And she has gone through menopause…

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