Sulfur is a mineral that is an essential part of the protein structure. The majority of the body's total sulfur content is concentrated in the muscles, skin and hair. When combined with hydrogen, sulfur helps to transfer energy to the muscles. Additionally, the red blood cells need sulfur to help in oxidizing the blood. In fruits the mineral is presented in the form of either amino acids or enzymes, which the body processes into sulfur.
Grapefruits (Citrus paradisi) are known for being a bitter citrus fruit, hailing from tropical climates. The fruit normally has a yellow, pinkish or greenish rind with a pale yellow or pink pulp. One of the reasons the fruit has been attributed for helping the body to burn fat is its levels of methionine, a sulfur-rich amino acid. The level of sulfuric amino acid in grapefruit can also help skin to retain its suppleness.
A fruit native to Mexico, avocado (Persea Americana) has a dark green skin with a lighter pulp that is high in monounsaturated fats. Avocados also are high in glutathione a tripeptide — which is formed when three amino acids are bonded together — that breaks down to cysteine after digestion. Cysteine is a sulfuric amino acid, making avocados a great source of sulfur. The fruit's content is similar to the levels found in protein-rich foods such as cheese and eggs.
One of the more popular tropical fruits, pineapple (Ananas comosus) is the product of a group of flowers coming together to bear one fruit. Whether fresh, dried or juiced, the pineapple is a good source of bromelain, a sulfur-rich proteolytic enzyme that is an anti-inflammatory. Bromelain can help the body to metabolize proteins and help to rejuvenate the skin. The sulfur level also helps to deter the fruit from turning brown when it comes in contact with air.
The watermelon fruit (Citrullus lanatus) is a large green melon that is actually classified by botanists as a "pepo," which means it is an oversized berry with a thick rind and deep pink innards. Watermelon is very nutritious and contains high amounts of glutathione — a tripeptide that also breaks down into the sulfuric amino acid, cysteine. The result is a significant level of sulfur that can help the blood to oxidize and skin to retain its brightness.