Skin health
Dietary and supplemented vitamins and minerals are as important as topical creams on skin health
When we think about skin care, the first thing that comes to mind is a topical cream or serum with supplemented vitamins and/or bioactive factors for healthy and radiant skin.
Topical application of cream or serum may not be sufficient and often time impractical to cover the largest organ of our body (i.e., our skin, ref. 1). That is why some manufacturer would customize such cream or serum to only targeted skin area (e.g., face, neck, hand, or specific skin problems such as uneven complexion or scarring), rather than to the whole body. In such cases, it would deprive other parts of your skin the same added advantage.
It is important to ensure that other parts of our skin are not neglected. Fortunately, our skin do get the nutrients, vitamins, and minerals from our daily diet. These would then be pumped to all corners of our body for distribution. Thus, to have a proper daily diet and to supplement our diet with vitamins and minerals are important to ensure a healthy skin (on top of using topical cream or serum).
Vitamins for skin
Vitamins that are essential for healthy skin can be grouped into fat-soluble and water soluble type.
Fat-soluble vitamins
Vitamin A is good for eye health and also skin. The daily recommended dietary allowance (daily RDA) is 700 to 900 microgram (or 2333 to 3000 IU), respective to gender. The upper limit is 3000 microgram (or 10000 IU).
Vitamin D is important for all cell types, not just skin cells. Fortunately, in tropical countries where your daily exposure to sunlight is sufficient, there is no lack of vitamin D. This is because our body can generate vitamin D from our body's cholesterol with the power of sunlight. Vitamin D plus calcium are usually associated with bone formation and we have seen milk fortified with vitamin D (but I think the added vitamin D is overkill because we can produce it freely with the help from the sun - unless we have inherited a disorder that disrupted the normal vitamin D metabolism such as Pseudovitamin D deficiency rickets, see ref. 5).
Vitamin E is an antioxidant, i.e., it removes free radicals or chemicals that can kill our cells. Free radicals are formed especially on your skin when exposed to the sun's UV light. We are fortunate because our skin acts as barrier to protect our body against harmful UV. Thus, it is important to ensure that we have a balanced nutrients, especially vitamin E that can help remove the UV-induced free radicals. The daily RDA is 15 mg. Also, if you look at the our regular sun-block cream, vitamin E (aka tocopheryl acetate) is usually supplemented as an inactive ingredient to minimize sunburn.
Vitamin K is important for the production of cellular materials required for many bodily functions, e.g., blood clotting, bone-formation, wound healing, and of course skin health too. The daily RDA is 122 to 138 microgram, respective to gender.
Water-soluble vitamins
Vitamin C is important for skin integrity and wound healing (ref. 2, 3). It is also an antioxidant. If you feel that your skin is dry or cracking, taking sufficient vitamin C would help to improve your skin condition. Remember that lack of vitamin C has been attributed to scurvy, i.e., a disorder with symptoms such as gum bleeding and a variety of skin conditions. The daily RDA is 75 to 90 mg with upper limit at 2000 mg (ref. 4). It is important to get vitamin C from fruits or salad where the vitamin is at its highest. This is because vitamin C gets unstable when cooked or stored over a long time. In contrast, vitamin C supplements are designed to be more stable over longer storage time (esp., within its recommended expiry date).
Vitamin B, e.g., B1 (daily RDA 1.1 to 1.2 mg), B2 (daily RDA 1.1 to 1.3 mg), B3 (daily RDA 14 to 16 mg and upper limit 35 mg), B5 (daily RDA 5 mg), B6 (daily RDA 1.5 to 1.7 mg and upper limit 100 mg), B7 (daily RDA 30 mg), B9 (daily RDA 400 microgram and upper limit 1000 microgram), and B12 (daily RDA 2.4 microgram).
Minerals
Sulfur helps keep the skin cells and fibers together. It is an essential material to produce keratin (a protein) that is responsible to produce our hair, nail, and skin.
Iron is important to help our skin grow and replenish (ref. 6). Its daily RDA is 8 to 18 mg and upper limit 45 mg. If we are omnivorous (in contrast to herbivore or vegetarian), our iron intake will be sufficient.
Calcium is required for normal homeostasis of our skin, i.e., it ensure that our skin is replenished (ref. 7). Its daily RDA 1000 mg (and upper limit 2500 mg) helps build a stronger bone as well as a lustrous skin.
Other essential microminerals (or trace minerals) are zinc (daily RDA 8 to 11 mg and upper limit 40 mg), iodine (daily RDA 150 microgram and upper limit 1100 microgram), selenium (daily RDA 55 microgram and upper limit 400 microgram), copper (daily RDA 900 microgram and upper limit 10000 microgram), manganese (daily RDA 1.8 to 2.3 mg and upper limit 11 mg), fluoride (daily RDA 3 to 4 mg and upper limit 10 mg), chromium (daily RDA 25 to 35 microgram), molybdenum (daily RDA 45 microgram and upper limit 4000 microgram), vanadium (daily RDA 1.8 mg), nickel (daily RDA 1 mg) and chromium (daily RDA 120 microgram and upper limit 200 microgram).
Other macrominerals (or major minerals) are sodium (daily RDA 2400 mg), chloride (daily RDA 3400 mg), potassium (daily RDA 3500 mg), phosphorus (daily RDA 1000 mg), magnesium (daily RDA 350 mg), boron (daily RDA 20 mg), and abovementioned sulfur and calcium.
Multivitamins/Minerals (MVMs) supplement
MVMs and multivitamins (MVs) supplements do not follow a harmonized standard (ref. 8) and it may be difficult to define what is multivitamins or multi-vitamins and minerals, but one way to characterize them are based on the following criteria
Broad spectrum MVMs are those taken once a day (containing all or most of the vitamins and minerals required daily)
High potency MVMs are those with higher concentrations but within the upper limits.
Specialized (targeted to consumers with specific conditions or needs), e.g., deficiencies or enhanced performance (e.g., athletes, body builders, or others).
For most of us, we should get broad spectrum MVMs unless there is a special need for high potency and specialized MVMs.
Glossary
Essential minerals
Our daily intake should have the following minerals, e.g., iron and calcium. Iron is for blood production whereas calcium is important for maintaining a healthy bone homeostasis.
Overage versus fortified
Overage is a term used to describe adding more than required to fortified food (or supplement) to factor in the loss caused by subsequent processing or storage.
Fortified is the term used to describe added nutrient supplement to processed food to ensure balanced vitamins and minerals per recommended daily intake of the processed food.
Topical
The term describes product for use on external surface (i.e., our skin) and not to be taken internally.
Vitamin stability and degradation
Water-soluble vitamins are more unstable (i.e., get depleted) during food processing or cooking. This is the drawback (or shortcoming) in our effort to extend food's shelf-life.
Reference
The skin is the body's largest organ, 2010 (https://pubmed.ncbi.nlm.nih.gov/21087182)
Role of Vitamin C in Skin Diseases, 2018 (https://doi.org/10.3389/fphys.2018.00819)
Vitamin C: a wound healing perspective, 2013 - a review (https://doi.org/10.12968/bjcn.2013.18.sup12.s6)
Listing of vitamins, 31 Aug 2020 (https://www.health.harvard.edu/staying-healthy/listing_of_vitamins), accessed 9 Jan 2022
Genetic disorders of Vitamin D biosynthesis and degradation, 2017 (https://doi.org/10.1016/j.jsbmb.2016.04.001)
Hirobe T. (2012) Iron and skin health: iron stimulates skin function. In: Preedy V.R. (eds) Handbook of diet, nutrition and the skin. Human Health Handbooks no. 1, vol 2. Wageningen Academic Publishers. https://doi.org/10.3920/978-90-8686-729-5_12
Bikle DD, Ng D, Tu CL, Oda Y, Xie Z. Calcium- and vitamin D-regulated keratinocyte differentiation. Mol Cell Endocrinol. 2001 May 25;177(1-2):161-71 https://doi.org/10.1016/s0303-7207(01)00452-x
Multivitamin/mineral Supplements. Fact Sheet for Health Professionals (https://ods.od.nih.gov/factsheets/MVMS-HealthProfessional/)
Recommended daily intake of vitamins and minerals (https://www.lenntech.com/recommended-daily-intake.htm)