While there are many nutrients that are important to our health, the following sixteen micronutrients are the most important for the gut and skin. For each nutrient, I will discuss its role in gut and skin health and provide a list of the best food and supplemental sources. Note that it is always preferred to get our nutrients from food (or sunlight) rather than from supplements.
Zinc helps maintain the structure of cell membranes and proteins and has anti-inflammatory effects. Zinc activates a protein called collagenase, which allows cells to remodel collagen during wound healing.1 Zinc supplementation has been shown to reduce gut barrier permeability,2,3 and it may help leaky skin as well. The earliest sign of zinc deficiency is usually patches of dry skin. Evidence suggests that supplemental zinc may reduce acne4 – in some cases, it has even been shown to be as effective as tetracycline antibiotics.5 This may be because it helps regulate sebum production in the sebaceous glands.
The best sources of dietary zinc are liver, kidney, beef, lamb, and shellfish. Plant foods like nuts and pumpkin seeds can be high in zinc, but it is less bioavailable due to high levels of phytates that bind the zinc. You can also supplement with up to 30 mg per day of zinc picolinate. Care should be taken to balance zinc and copper intake.
2. Vitamin A
Vitamin A modulates skin growth factors, promotes epidermal differentiation, inhibits sebaceous gland activity, suppresses androgen formation. It also inhibits enzymes that degrade collagen with aging.6 Vitamin A has also been shown to induce gut-homing regulatory T cells and promote tolerance of the gut mucosal immune system.7,8 Synthetic Vitamin A derivatives have been used for decades as an effective treatment for severe acne and psoriasis.9 Rough dry skin and keratosis pilaris, or “sandpaper” bumps on the backs of the arms, are common signs of vitamin A deficiency. Transport of Vitamin A in the blood depends on zinc, so these two nutrients may work together promote the health of the gut, skin, and immune system.
The best source of bioavailable Vitamin A is liver and cod liver oil. Vitamin A can also be obtained from the precursor beta-carotene, which is found in carrots, sweet potatoes, collards, and asparagus. Note that absorption of beta-carotene is very poor unless these foods are paired with fat.
3. Vitamin D
Vitamin D is produced in the skin in response to UV light. Vitamin D helps regulate skin cell metabolism and growth and has been shown to be helpful in the treatment of itching and psoriasis.10 Vitamin D metabolism results in the formation of cathelicidin, which has antimicrobial properties. Cathelicidin deficiency can predispose to certain types of eczema.11
Vitamin D also has benefits for the gut. The gut expresses very high levels of the Vitamin D receptor.12 Vitamin D in the gut has been shown to help maintain gut barrier function and a balance of good gut bacteria.13 Deficiency of Vitamin D has been associated with an increased risk of inflammatory bowel disease.14
Whenever possible, it’s best to get Vitamin D from sunlight. In cases where adequate sunlight cannot be obtained, I recommend supplementing with Vitamin D3/K2 until blood levels of 25’OH-D reach 35-50 ng/mL. Those with autoimmune disease or autoimmune-like skin conditions may benefit from a level closer to 50 ng/mL.
4. Vitamin C
Vitamin C acts as an antioxidant and can help prevent UV-induced skin damage. It is also essential for several enzymes involved in the synthesis of collagen.15 Deficiency of Vitamin C causes scurvy, with the first signs and symptoms being rough, dry skin and abnormal hair growth. Vitamin C deficiency may also contribute to skin wrinkling and impaired wound healing.16
Good sources of Vitamin C include bell peppers, dark leafy greens, broccoli, brussels sprouts, citrus fruits, kiwi, guava, strawberries, and certain herbs. You can also safely supplement with up to 1,200 mg of Vitamin C. I recommend one made from concentrated berries like camu-camu and acerola, as these also have the added benefit of other bioflavonoids, polyphenols, and antioxidants.
Selenium is an essential trace mineral and a component of the selenoprotein glutathione peroxidase (GPx), an enzyme that helps regenerate glutathione, the body’s master antioxidant. Studies have found that patients with severe acne have low levels of selenium and GPx activity and that supplementing with selenium can increase GPx activity and reduce acne severity.17 Selenium may also protect the skin against UV damage.18
Glutathione is also required for normal gut function, protecting epithelial cell membranes from damage and helping to maintain the fluidity of the mucus layer, and depletion of glutathione increases bacterial translocation from the gut.19 Selenium-enriched diets have also been shown in increase gut microbial diversity.20
Sources of selenium include brazil nuts, walnuts, red snapper, liver, herring, onion, and poultry. You can also supplement with 100 mcg of selenium in the selenomethionine form. Note that iodine and selenium should typically be supplemented together.
6. Vitamin E
Vitamin E is a fat-soluble vitamin and the most abundant antioxidant in the skin. It is delivered onto the skin surface via the sebum and then penetrates all the underlying layers of skin.21 Vitamin E is essential for protecting the cells of the skin from free radical damage due to sun exposure and other inflammatory insults. Deficiency is extremely common, particularly in those with inflammatory gut conditions and fat malabsorption, and can alter collagen cross-linking and cause skin ulcerations.22,23
Most Americans get their Vitamin E from industrial seed oils like soybean, canola, and corn oil, but the preferred sources of Vitamin E are almonds, eggs, walnuts, avocados, asparagus, spinach and other leafy greens, sunflower seeds, pine nuts, and olives. I do not recommend supplementing with Vitamin E, as studies have shown that long-term supplementation may increase the risk of cardiovascular disease.
Silica is a lesser-known trace mineral that can have a major impact on skin health. Several enzymes required for the synthesis of collagen and formation of connective tissue depend on silica.24 Silica may, therefore, help improve the appearance of the skin and reduce signs of skin aging.
Food sources of silica include leeks, apples, green beans, strawberries, cucumber, oranges, mango, celery, asparagus, fish, and seeds. You can also supplement by adding trace mineral drops to your water.
8. B Vitamins
Riboflavin (Vitamin B2): deficiency of riboflavin can cause lesions on the outside of the lips, corners of the mouth, dermatitis, and other inflammatory skin conditions.
Niacin (Vitamin B3) is crucial for DNA and fatty acid synthesis. The classic niacin deficiency disease, pellagra, is characterized by dermatitis, among other symptoms. Topically, niacin has been shown to help increase moisture in the skin, reduce skin aging, and is a fairly effective treatment for acne, rosacea, or redness of the skin, though few studies with oral niacin and skin health have been performed.25
Pantothenic acid (Vitamin B5) plays a central role in metabolism and accelerates wound healing by increasing cell division and speeding up cellular migration.26,27 It also increases levels of glutathione.28
Vitamin B6 is involved in the conversion of the excitatory neurotransmitter glutamate to the inhibitory neurotransmitter GABA. GABA has been shown to reduce the feeling of itch.29 Vitamin B6 also acts as a cofactor for diamine oxidase, the enzyme that degrades histamine, and supports methylation. Deficiency results in scaly dermatitis.
Biotin (Vitamin B7) acts as an essential cofactor for enzymes that regulate the metabolism of fatty acids. Fatty acids are crucial for preventing water loss from the skin. Deficiency of biotin causes hair loss and a scaly, erythematous or seborrheic dermatitis that often develops around the mouth or on the face and scalp.30
Methylcobalamin (Vitamin B12) and folate (Vitamin B9) are involved in the methylation cycle, which is how the body detoxifies substances and eliminates them from the body. Deficiencies of folate and B12 are common in those with celiac disease, inflammatory bowel disease, or SIBO.31,32 Folate deficiency can result in dermatitis, while Vitamin B12 likely influences the composition of the microbiota.33
B vitamins are found in a wide variety of foods, but are most abundant in meat, especially organ meats, and eggs. Some B vitamins are also produced by the gut microbiota.34 You can also supplement with a good quality B vitamin complex, but be sure to choose one with activated forms of these vitamins (methyltetrahydrofolate, methylcobalamin, and pyridoxal-L-phosphate). Note that high-dose B12 may exacerbate acne in some individuals.35
9. Vitamin K2
Vitamin K2 synergizes with vitamin A and vitamin D and is required for many of their functions.36 Vitamin K2 binds calcium and prevents the calcification of elastin, a protein that keeps the skin stretched tight and wrinkle-free.
Good sources of Vitamin K2 include grass-fed dairy products, pastured egg yolks, liver, and fermented foods like sauerkraut. Gut bacteria can convert some K1, primarily found in leafy green vegetables, into vitamin K2. Vitamin K can also be supplemented as high-vitamin butter oil or Vitamin D3/K2.
Manganese is not typically included in a discussion of nutrients for skin health. Yet manganese is required for collagen synthesis, and deficiency can cause slow hair and nail growth and a reddening of the skin. Deficiency can also cause miliaria crystallina, commonly called “heat rash” or “sweat rash”, a form of dermatitis that results from blocked sweat glands, which appear as tiny clear bubbles on the skin.37 This can also occur from sunburn, fever, or excessive sweating. Manganese is also required for the function of superoxide dismutase, which protects against oxidative stress in the mitochondria of the gut and skin.38
Good sources of manganese include seafood, nuts, seeds, spinach, pomegranates, and black tea. You can also supplement by adding trace mineral drops to your water.
Iron is a cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase, which catalyze the formation of hydroxyproline39 and hydroxylysine, respectively. These modified amino acids are crucial for the structural stability of collagen. Severe iron deficiency leads to anemia, which can cause pale skin, fatigue, weakness, and lightheadedness. This can also influence the gut and skin since blood is preferentially shunted to the brain and heart.
The heme form of iron is the most bioavailable. Heme iron is found in clams, oysters, liver, venison, mussels, and beef. Non-heme iron can be found in pumpkin seeds, hazelnuts, spinach, tomatoes, and some herbs. Iron absorption is increased by vitamin C, and reduced by egg yolks, oxalates, phytates, polyphenols, and calcium. I do not recommend supplementing with iron unless absolutely necessary since unabsorbed iron can promote the growth of gut pathogens.
Magnesium is a cofactor for more than 300 enzymes, including many involved in the production of cellular energy. Magnesium is important for maintaining normal gut barrier function,40 and deficiency of magnesium has been shown to alter the gut microbiota and lead to depressive-like behavior.41 Magnesium can also help with gut motility and bowel regularity. Topically applied magnesium salts have also been shown to accelerate skin barrier recovery.42
Good sources of magnesium include almonds, cashews, spinach, avocado, bananas, salmon, and halibut. Magnesium content is heavily dependent on soil concentration of magnesium, and most people will not be able to get enough through food alone. I highly recommend supplementing with 400 mg of magnesium glycinate daily.
Potassium is an essential electrolyte in the body and the major positively charged ion in the intracellular space. Potassium, therefore, helps control the volume of cells and helps the skin stay moisturized.43 It also helps the skin produce new skin cells. Deficiency in potassium can lead to dry skin and hair loss.
Many fruits and vegetables are good sources of potassium. Potassium is highest in potatoes, sweet potatoes, plantains, squash, mushrooms, tomatoes, bananas, and avocados. Some fish, such as salmon and halibut, also contain potassium. The average American consumes less than half of the estimated potassium intake of our hunter-gatherer ancestors. It is not recommended to supplement with potassium.
Sulfur is an extremely important nutrient and the third most abundant mineral in the body. Animals fed a diet deficient in sulfur produce less collagen, suggesting that sulfur is required for collagen synthesis. Sulfur is also required for the crosslinking of keratin filaments in the epidermis.44 Sulfur is also required for the synthesis of the glutathione, an endogenous antioxidant important for protecting the gut, skin, and other tissues from free radical damage.
Sources of sulfur include egg yolks, poultry, red meat fish, garlic, onions, asparagus, brussels sprouts, broccoli, cabbage, and kale. Fermentation may increase the bioavailability of sulfur in cruciferous vegetables.
Copper activates an enzyme called lysyl oxidase, which cross-links mature collagen fibers with other supportive fibers like elastin, helping to form a scaffold that keeps skin strong.45 Copper is also important for mitochondrial health and is a cofactor for several antioxidant enzymes. Copper deficiency may exacerbate histamine intolerance,46 and can also cause hypopigmentation of the hair and skin.
Food sources of copper include beef liver, oysters, crab, dark chocolate, mushrooms, almonds, cashews, and sunflower seeds. If you supplement with copper, it’s very important to balance this with zinc. The ratio of zinc to copper should be kept between 2:1 and 15:1 for optimal health.
Choline is a vitamin-like nutrient that is a key component of the phospholipids that make up cell membranes. Choline is also a precursor to the neurotransmitter acetylcholine, which stimulates the production of gastric acid and is thought to be important for skin barrier integrity.47 The transport of fat and cholesterol from the liver also requires choline, so it is also important for moderating the gut-liver-skin axis.
The best sources of choline are beef liver, eggs, muscle meat, and fish. Plant foods like potatoes, Shitake mushrooms, Brussels sprouts, and broccoli can also provide some choline. Choline can also be taken as a supplement in the phosphatidylcholine form. Some choline can be produced in the body from betaine, which may be more likely to be absorbed in those with gut dysbiosis or SIBO. The top food source of betaine are beets, spinach, sweet potato, and muscle meat. Those with SIBO should consider supplementing with betaine HCl.
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