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  • Rajani Katta MD

What you've heard on the Internet about skin and diet, and why so much of it is wrong

Updated: Aug 16, 2020

Are you tempted to buy the latest hair, skin, and nail supplement? Or go gluten-free because your favorite celebrity said it helped her skin? Before you take another step, make sure you know the evidence.

Because there are many, many myths and misconceptions out there.

And that's a shame, because there's actually strong evidence linking skin and diet. And those evidence-based recommendations HAVE been shown to promote healthy, youthful, glowing skin.

Here are just a few of the common myths about skin and diet:

Myth #1: Taking high dose antioxidant supplements will prevent sun damage

Antioxidants are all the rage lately. But there's a big difference between a mega dose of antioxidants and the RIGHT dose of antioxidants. Research has found that those mega doses may actually backfire. In just one example, smokers who took beta-carotene supplements actually had higher rates of lung cancer. I call it the Goldilocks principle, and it applies to medications, to vitamins, AND antioxidants. You don't want too little (deficiency) and you don't want too much (toxicity).

In fact, some studies have suggested that the ideal dose of antioxidants is the dose provided by whole foods. In one study, volunteers who consumed lycopene-rich tomato paste every day for 12 weeks had less of a sunburn response after being exposed to UV radiation.​

Myth #2: Biotin has been shown in research studies to strengthen skin, hair, and nails

Several small studies have found that biotin supplements may indeed help strengthen nails, but it's important to recognize that they've never been shown to strengthen skin and hair. Despite that lack of research, biotin is found in many of the skin, hair, and nail supplements that are becoming increasingly popular.

And one other thing about biotin: those bottles need to carry a gigantic warning. Biotin supplements have been shown to interfere with some important blood tests, including tests for thyroid function and even heart attacks.

Myth #3: For better skin, you need probiotics.

Probiotics HAVE been shown in some studies to help with skin hydration and skin inflammation, but the strongest recommendations aren't for probiotics: they're for synbiotics. Synbiotics are a combination of probiotics [live microorganisms that may have health benefits, and which may be found in certain foods or probiotic supplements] and prebiotics [which provide the food that helps those microbes grow and thrive].

In other words, your probiotics should always come with a side of broccoli [or another food source that helps them thrive].

​​Myth #4: Fried or greasy foods make acne worse

Actually, it's not the grease. While too many french fries and late night pizza may worsen your acne, it's not because of the grease. It's because of the processed carbohydrates.

Foods heavy in added sugar and processed carbs can cause elevations in blood sugar levels. That sets off a cascade of hormones in the bloodstream that ultimately lead to skin inflammation and even increased oil production.

Which means that even non-greasy white rice and white pasta can worsen acne. And it especially applies to any foods heavy in sugar, such as sugar-loaded sodas, sports drinks, and coffee drinks. ​

Myth #5: Everyone with skin inflammation (including from eczema, psoriasis, or acne) should go gluten-free.

Gluten is NOT inherently inflammatory, and it doesn't cause any problems at all in the vast, vast majority of people. Think about it: there are billions of people across the world who eat bread and still have great skin.

But the reason it's often mentioned in blog posts is that there are SOME individuals who benefit from avoiding gluten. How can you find out if you're one of those individuals?​

  • ​Eczema/atopic dermatitis: Some patients with eczema have an allergy to wheat. Although it's a small percentage, if you suspect it's a trigger, then I recommend starting with a food diary. Pay attention to the 48 hours prior to any skin flares, because sometimes food allergies can take that long before they cause a flare of eczema.

  • Atopic dermatitis with GI symptoms: For adults with atopic dermatitis and irritable bowel syndrome, a gluten-free diet may be recommended. That's because some cases of IBS are due to gut dysbiosis, an imbalance of the microbes that live in your gut. Studies have found that patients with atopic dermatitis have a higher risk of these gut microbe imbalances, and therefore may have a harder time processing gluten.

  • Acne: Researchers haven't found any link between acne and gluten. However, they have found a strong link between acne and processed carbohydrates. That may explain why some patients with acne notice an improvement in acne when they eliminate gluten: they may actually be eliminating sugar and processed carbs.

  • Psoriasis: If you have psoriasis, and you have symptoms such as abdominal pain and diarrhea, then you may need to be tested for gluten antibodies. In one study, about one in seven psoriasis patients had these antibodies. This group (and only this group) noted an improvement in their psoriasis when they went gluten free.

The Bottom Line: Just because it's popular, doesn't mean that the latest diet recommendation claiming to promote healthy, radiant skin will actually help. It's important to learn the research and to choose evidence-based strategies.


Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.

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