Humans carry an inactivated version of the gene that allows the body to produce vitamin C internally, possibly because as humans became more mobile, it was possible to supplement the vitamin with fruits and plants. — KAROLINA GRABOWSKA/Pexels
The story starts with a startling situation in Britain, repeated in almost every other advanced country in the world. According to a recent study by Imperial College, London, the rate of food allergies in Britain doubled between 2008 and 2018. The UK Food Standards Agency now estimates that 6% of the British population has a clinically confirmed food allergy.
This may be an underestimate because over 30% of the UK population reported diverse adverse reactions to different kinds of foods, but only 6% or so were able to be confirmed as definite allergies by clinical assessments of various known allergen triggers.
The situation is worse with younger people where between 5% to 8% of UK children are living with real food allergies. Such allergies can sometimes be so severe that they can cause death. A young lady was killed recently by a few drops of cow’s milk in her hot chocolate from a café.
It must be a nightmare to live in a situation that relies on cafes, restaurants, and food suppliers to be ultra-careful and diligent with the food that they serve. Because, inevitably, mistakes and oversights will happen, with extremely dire consequences.
After all, a food allergy is simply the immune system overreacting to various foods, stimulating the release of compounds that result in symptoms such as itchy skin, hives, swollen faces, eyes, or lips, shortness of breath, and even cardiac failure. An allergy is another way of saying that the immune system is malfunctioning.
There are many explanations proposed for this astounding increase in Britain and global allergy rates. Lots of research has blamed ultra-processed foods (UPF), the “foods” on most of the shelves in modern supermarkets.
These accusations have weight, because it is certain that poor nutrition will not result in good health outcomes, and one of the negative outcomes may be allergies. Research on such foods also suggests that the damage done by UPFs is not necessarily direct, as the main impact seems to be on the Human Gut Microbiome (HGM). This topic has already been explored in an earlier article titled ‘Allergic Reaction’.
There are also environmental causes. Exposure to various insects and microscopic fauna in house dirt, bedding, and furniture is also a known cause of allergies. Again, this has already been explored in 2019, in this article, titled ‘Allergies’ on The Star Online.
Vitamin C
But the subject I really want to talk about today is vitamins, in particular, the odd history of Vitamin C and Vitamin D. Both are crucial to a properly functioning immune system and they have interesting ways of complementing each other in the fight against diseases/pathogens.
Vitamin C helps support the immune system in several important ways. It enhances white blood cell function; e.g. increasing production and function of white blood cells like neutrophils, lymphocytes, and phagocytes, and promotes a process called neutrophil chemotaxis (movement of white blood cells toward sites of infection). As a result, white blood cells can have 50-100 times the levels of Vitamin C than other cells.
Vitamin C is also a powerful antioxidant, protecting immune cells from oxidative stress and free radical damage. It is also involved in regenerating other antioxidants such as glutathione (used to remove toxins from the body). It also boosts mucosal immunity in the nose and throat, which is why this vitamin is often recommended for colds and flu.
Optimal sources of Vitamin D can be found in animal and fish fats. — IVAN SAMKOV/Pexels
But what makes Vitamin C really interesting is that humans still have the original gene that can allow the body to manufacture the vitamin internally. If the gene is active, then like cats and dogs, we will never need to eat any foods with Vitamin C because the liver can manufacture all the amounts needed by the body.
However, humans carry an inactivated version of the gene that produces the enzyme needed for the synthesis of Vitamin C. The enzyme is called l-gulono-lactone oxidase (or GLO), and the same faulty gene is also present in some other mammals such as “dry-nosed” primates (such as apes, monkeys, and tarsiers), guinea pigs, bats, and capybaras.
Nobody is certain why this GLO gene had been disabled, but it may be because the overhead costs of self-production were too high. Also, as mammals became more mobile, it was possible to enhance the diet with more fruits and legumes containing the vitamin.
A study suggested that mammals evolved an intriguing way to get around the limitation of not being able to manufacture the vitamin. Primarily, it means that the use of Vitamin C from the diet is made around 100 times more efficient via specialised “transporter” cells (utilising a mechanism too difficult to explain here). This significantly lowers the amounts of Vitamin C required, which can be replenished from gathered fruits and other plants.
Vitamin D
Humans can produce Vitamin D from sunlight, and happily so because this is a critically important nutrient, especially for the immune system, in particular the adaptive (or acquired) immune system. The adaptive immune system is a sophisticated defence mechanism that can “recall” past diseases (or vaccinations) and activate specialist white blood cells called lymphocytes (further divided into B cells and T cells), specifically targeted against known past pathogens and their close relatives. For more on how this works, you might like to review an earlier column from 2020 titled ‘Presidential Nutrients’.
Cows and pigs and many livestock animals such as sheep can also produce Vitamin D from sunlight, and in most cases, they produce it even more efficiently than humans. However, it should be noted that this vitamin is so important that humans evolved and retained the ability to make it internally. This may also be because the optimal sources of Vitamin D are animal and fish fats, foods that were not readily available to ancient humans.
The ability of humans to produce this crucial nutrient from sunlight also decreases with age, around 13% for every decade after the age of 20. Therefore, a 60-year-old has lost roughly more than half the capacity to generate the vitamin.
This can be problematic as older humans need even more Vitamin D along with an effective immune system to combat diseases. A person fighting any disease has roughly an additional requirement of around 37.5% more Vitamin D. And the vitamin is also crucial for healing processes as explained in my recent column titled ‘The Recovery After’.
A study in 2018 showed that children who lacked exposure to sunlight had three times the risk of getting an egg allergy and 11 times a risk of getting a peanut allergy. — RON LACH/Pexels
Currently, around 50% of the world’s population have Vitamin D insufficiency, and around 1 billion people has actual Vitamin D deficiency. Apart from the potential of poorer immunity, there are other negative effects of Vitamin D deficiency.
Vitamin D is crucial for calcium absorption and bone health. The vitamin enhances calcium absorption in the intestines, allowing the body to absorb dietary calcium more efficiently. It helps to maintain the proper calcium and phosphate levels necessary for bone formation, density, and mineralisation. Without adequate Vitamin D, the body can only absorb only 10-15% of dietary calcium, compared to 30-40% absorption when the vitamin levels are normal.
Furthermore, Vitamin D has several other important roles, such as cell differentiation (when new cells are formed from stem cells), and neuromuscular function (the messaging between neurons and muscles). Research also indicates potential protective effects against certain cancers, cardiovascular diseases, autoimmune diseases, and other chronic conditions.
It is an odd fact but dogs and cats cannot manufacture Vitamin D in their bodies, and they must get it from their diets. This is probably due to their prehistoric ancestors’ success in hunting other animals that can produce Vitamin D.
If you are curious, there are mammals which can synthesise both Vitamin C and D in their bodies. Examples are cattle, mice, and rats though it is unclear whether they can make enough of the nutrients without supplementation from their diets.
Allergies, again
It should be evident that both Vitamin C and D are critical nutrients for a healthy immune system, but in terms of allergies, there was an interesting and potentially significant observation in the development of childhood allergies.
A joint US/Australian study in 2018 into geographic patterns of food allergies has found a link to non-exposure to sunlight (and a deficit of Vitamin D). A lack of sunlight, especially in heavily urbanised areas (where kids spend most of their time indoors) caused infants and young children to triple the risk of getting an egg allergy and have up to 11 times more risk of a peanut allergy.
The views expressed here are entirely the writer’s own.
