*3.6. Minerals*

Seaweeds comprise greater numbers of important minerals, such as macroelements (e.g., Na, Ca, P, Mg, K) and trace minerals (like, Fe, Zn, Mn, Cu) due to their marine environment [118]. Minerals and cell wall polysaccharides (such as agar, alginic acid, alginate, or cellulose) play critical roles in the formation of human tissues or the regulation of crucial reactions as cofactors of some enzymes as cofactors among some enzymes [107]. As a result, seaweeds are important source of minerals and, when consumed regularly, have been recognized as advantageous functional foods (i.e., food supplements) [98]. It is worth noting that brown algae have greater mineral content than red algae [118].

Furthermore, elements such as Fe or Cu are found in higher concentrations in seaweeds than in meats and spinach [43]. Seaweeds were identified to be a promising supplier of iodine, which occurs at different chemical components, or brown algae, which contains more than 1% moisture content; its buildup in seaweed tissues may be 30,000 times greater than its concentration in sea water [45]. Iodine, which comes in a variety of forms, is anti-goiter, anticancer, antioxidant agent or a key nutrient in metabolic control. However, excessive intake may result in some unfavorable effects [43].

Green seaweeds have a Na+/K+ ratio of 0.9 to 1, red seaweeds have a ratio of 0.1 to 1.8, and brown seaweeds have a ratio of 0.3 to 1.5. This ratio was found to be especially low in *Palmaria palmata* (0.1) and Laminaria spp. (0.3–0.4) from Spain [199]. Because the World Health Organization (WHO) recommends a Na+/K+ ratio close to one, consumption of food products with this proportion or lower should be examined for healthy cardiovascular purposes [199]. In contrast, using seaweeds as NaCl replacements in processed meals could be a useful technique for reducing overall Na+ consumption while boosting intake of K+ and other lacking components that would otherwise not be present in NaCl salted foods. In addition to Na<sup>+</sup> and K+, Ca2+ and Mg2+ intake is linked to cardiovascular health. Indeed, it was proposed that enough Mg2+ intake may lower blood pressure by acting as a calcium antagonist on smooth muscle tone, inducing vasorelaxation [200].

Green seaweeds accumulate Mg2+ more than Ca2+, whereas brown seaweeds do the opposite. In turn, with the exception of *Phymatolithon calcareum*, which can accumulate exceptionally high concentrations of Ca2+ [201], red seaweeds generally have lower, but balanced, amounts of these two minerals compared to the two other macroalgae types. It should be noted that the Ca/Mg ratio is also important in terms of calcium absorption because a lack of magnesium can result in a buildup of calcium in soft tissues, resulting in the production of kidney stones and the formation of arthritis [202].

Finally, phosphorus (P) levels appear to be similar in the three macroalgae groups, with values ranging from 0.5 to 7 g/kg DW. Notably, Fe is prevalent in all three macroalgae types, while Chlorophyta has a greater rate than Rhodophyta and Phaeophyta. However, at low doses, some species from the chlorophyta phylum (e.g., *Alaria esculenta*, *Saccharina latissima*, and *Fucus* spp.) might also be proposed to be a good source of Fe, as accumulation in some cases can exceed 1 g/kg DW [203]. In turn, the maximum Mn concentrations were found in red seaweeds, specifically *Chondrus crispus*, *Palmaria palmata*, and *Gracilaria* spp. [204]. Dawczynski et al. [205] also described the preferential deposition of Mn by red macroalgae over brown macroalgae.

The production of seaweed-fortified foods with the goal of reducing NaCl consumption and increasing nutritive value has been notably emphasized in meat-based products. López-López et al. [206] conducted outstanding work in the reformulation of many meat products, partially replacing the application of sodium chloride with diverse species of edible seaweeds while retaining their textural and sensory qualities. This research group created meat emulsions, meat patties, and frankfurters enriched with *Undaria pinnatifida*, *Himanthalia elongata*, or *Porphyra umbilicalis* that were both low in Na+ and rich in K+, presenting Na+/K+ ratios below 1, which is much smaller than the ratios above 3 observed in their traditional recipes [207,208].

Furthermore, increasing the mineral content of meat, fish, and other animal-derived products can be accomplished by providing algae-supplemented diets to animals. Similarly, supplementing fish with seaweed-fortified meals has been shown to be an efficient way of increasing the iodine content of their fillets. Milk, dairy products, and, more recently, plant "milks" (e.g., soy, almond, oat, and rice) are another category of food products that play a critical role in the dietary routines of specific geographical areas of the world and, as such, are ideal candidates for macroalgae supplementation [209].

#### *3.7. Vitamins*

Vitamins are needed for a variety of skin functions and can be obtained from food or by topical application. Supplementation is indicated for skin protection against dryness and premature aging, aesthetic UV protection, and sebaceous gland secretory activity modulation. Vitamins are frequently found in skin care products or cosmetics. Vitamins A, C, E, K, or vitamin complex B seem to be the most essential or medically proven vitamins for skin photoaging treatment or prevention [77], as well as most abundant vitamins through algae have been vitamins A, B, C, or E [210].

Some seaweeds contain vitamins with several health benefits and antioxidant activity, which help to lower a variety of health issues such as high blood pressure, cardiovascular illnesses, and the risk of cancer [211]. Various seaweeds have been found to include watersoluble vitamins B1, B2, B12, and C, as well as fat-soluble vitamins E and β-carotene with vitamin A activity [212].

Vitamin A (β-carotene), in the form of retinol, has antioxidant and anti-wrinkle qualities [213] and is used in cosmetics to reduce hyperpigmentation or fine wrinkles on the face [214]. Vitamin B complex is found with higher concentrations in green or red seaweeds (B1, B2, B3 or niacine, B6, B9, B12, or folic acid) [215]. Active forms of vitamin B3 found in skincare products contain nicotinate esters, niacinamide, or nicotinic acid. Niacinamide is antioxidant that lowers hyperpigmentation (also caused by blue light) and enhances epidermal features by lowering trans-epidermal water loss [216]. Red algae or other species are good sources of vitamin B12, which has anti-aging characteristics or is required for hair, nail growth, or health in vegetarians [217].

Vitamin C is employed in cosmeceutical production because it contains L-ascorbic acid, the bioactive version of which is most well-known [213]. In this context, Ceramium rubrum and *Porphyr leucosticta* are red algae with elevated vitamin C content. This vitamin possesses antioxidant, antiviral, anti-inflammatory, antibacterial, detoxifying, or anti-stress properties when applied topically and could be used to improve tissue growth, repair blood vessels, teeth or bones [218]. A previous study found that if it is present in optimum concentration in cosmetic product, it can improve complexion, reduce pigmentation, and inflammation [219]. Vitamin C suppresses tyrosinase by interacting to copper ions that reduces melanogenesis, according to several studies [213].

Water-soluble vitamins, such as vitamin C, are abundant in *Ulva lactuca*, *Eucheuma cottonii*, *Caulerpa lentillifera*, *Sargassum polycstum*, and *Gracilaria* spp. and aid in the inhibition of low-density lipoprotein (LDL) oxidation and the creation of thrombosis/atherosclerosis [220]. Red algae have significantly higher levels of dried carotene (e.g., 197.9 mg/g in Codium fragile and 113.7 mg/g in *Gracilaria chilensis*) than other vegetables (e.g., 17.4 mg/g in *Macrocystis pyrifera*) [98], while brown seaweeds (e.g., *Undaria pinnatifida*) have greater concentrations of a-tocopherol/vitamin E (99% vitamins) than green and red seaweeds [107].

The primary fat-soluble vitamins (A and E) boost nitric oxide (NO) and nitric oxide synthase (NOS) activity, which aids in the prevention of CVDs [220]. Furthermore, vitamin E has antioxidant properties that can limit the oxidation of LDL [211]. Many disorders, such as chronic fatigue syndrome (CFS), anemia, and skin problems, are caused by a lack of water-soluble vitamins such as B12. Most terrestrial plants do not synthesize vitamin B12, but numerous prokaryotes that can synthesize vitamin B12 interact with seaweeds, and this interaction enhances vitamin levels in macroalgae [221]. Arthrospira (previously *Spirulina*) (Cyanobacteria) contains four times more vitamin B12 than raw liver [222]. Brown and green seaweeds are high in vitamin A, with 500–3000 mg/kg dry weight on average, but red algae have 100–800 mg/kg dry weight [223]. When compared to terrestrial plants, seaweeds such as *Crassiphycus changii* (previously *Gracilaria changii*), *Porphyra umbilicalis* (Rhodophyta), and *Himanthalia elongata* (Ochrophyta, Phaeophyceae) are high in vitamins [224]. Vitamins (A, B, C, D, and E) are found in seaweeds and are widely used in skincare [225].

Vitamin C minimizes the severity of allergic reactions to infection, boosts the immune system, regulates the creation of conjunctive tissue, and aids in the removal of free radicals. It also plays an important role in many diseases and disorders such as diabetes, atherosclerosis, cancer, and neurodegenerative problems [226]. The brown seaweeds Ascophyllum and *Fucus* sp. have higher levels of vitamin E (α-tocopherols) than other red and green seaweeds [227]. The seaweed *Macrocystis pyrifera* (Ochrophyta, Phaeophyceae) is high in vitamin E, similar to plant oils recognized for their vitamin E content, such as soybean oil (*Glycine max*), sunflower seed oil (*Helianthus annuus*), and palm oil (*Elaeis guineensis*) [227]. Vitamin E prevents the oxidation of low-density lipoprotein and is also effective in reducing the risk of cardiovascular disease [228].
