Beta carotene deficiency although uncommon leads ultimately to death; however a shortage is very common affecting many tissues of the body because of the dearth of fresh yellow and orange foods in the Western diet.
A healthy skin, excellent vision, strong bones, resistance to infections and host of serious cancer related diseases is what a deficiency of this phytochemical causes; this is not small beer!
Poor health is additive. For example, if you have a marginal deficiency, and you are stuck all day in front of a computer, or, heaven forbid, the television then women in particular are almost certain to suffer from disabling fractures of their bones when they get older.
In fact hip fractures are now beginning to happen before fifty years of age because of our poor diet and sedentary existence; this doesn't just happen to other people.
Beta carotene deficiency is rare as this precursor to vitamin A is found in many vegetables and fruits. Nevertheless many have a serious shortage from their diets; taking it in pill form is unnecessary and potentially dangerous. You have to be a real meat and potatoes man to become frankly inadequate and die from an insufficiency.
Let's talk first just for a moment about colour. An object would appear white because it absorbes none of the spectrum, but it would look orange or yellow if the greens and blues are taken up by the pigments in the material.
Beta-carotene has a structure - its alternating double bonds if you want to know about the chemistry - that absorbes those other colours but not the yellow which is then reflected to our eyes, so we perceive it as having an orangey appearance.
So a beta carotene deficiency means you wouldn't perceive colours well.
Beta-carotene is the molecule found in foods such as butternut, pumpkins, carrots, sweetcorn and the yolk of an egg that gives them their orange colour. It's an extremely important phytochemical without which we cannot be healthy. The RDA is around 10,000 units per day.
Probably its most important function - but let's not underestimate its anti-oxidant properties that mop up free radicals preventing cancer - is by splitting in two in the liver it is changed into a compound called retinol, which is vitamin A.
Insufficient beta-carotene rich foods in the diet means you will be deficient in vitamin A; now it becomes serious.
The eye is a most wonderful organ, and highly complex; vitamin A, as we've said retinol, is changed to another form called retinal (the aldehyde for the chemistry bofs) which then combines with a group of proteins in the retina called opsins; when light strikes them, like a photovoltaic panel, they turn the energy into an electrical impulse. That passes down the optic nerve and ultimately we can 'see' an object when it reaches the visual cortex. We are fearfully and wonderfully made, but a beta carotene deficiency will ruin it all.
So, vitamin A, alongside lutein and zeaxanthin are vitally important phytochemicals that enable us to see properly and not go prematurely blind; a deficiency is the cause of age-related macular degeneration and cataracts.
One cannot go all day worrying about whether we have eaten enough of this and that phytochemical; there are thousands and keeping track would be impossible and drive us crazy. There's a simple solution; enjoy at least seven to ten coloured foods every day; then you can be sure you'll be getting enough of most or all of them.
You can't easily overdose with beta-carotene from your food, but you certainly can if you are taking supplements of beta-carotene or vitamin A; let your food be your medicine.
The exception is large amounts of liver, particularly from animals that eat a lot of fish. From plant sources it is not as well absorbed, and overdosing is impossible; more likely a beta carotene deficiency; enjoying it with a little fat improves the absorption so we have plenty of butter with our vegetables or avocado and olive oil with salads; the fat also lowers the glycemic index, not unimportant in those who are prediabetic.
From our food, there is a decreased risk of lung cancer, but numerous studies have shown that high doses of supplements, particularly in smokers, actually increases the possibility of malignant tumours.(1)
A beta-carotene deficiency has a profound effect on bone health; the phytochemical stimulates the osteoblasts, the cells that lay down new tissue.
However, an overdose also stimulates the osteoclasts that break down bone; this can never happen from plants sources of the vitamin but can from supplements and a large amounts of liver in the diet.
This roasted butternut squash recipe is definitely my favourite source of beta-carotene. One cup will provide you with sufficient for all your needs each day. Growing butternut squash is an easy vegetable to plant, but you do need a large garden; it's also one of those gourds that keep for long periods of time, so by all means get it from the greengrocer.
Its favourite spot is in the compost heap; then you can be sure the nutrients will be far superior to anything from a commercial farmer, but one can't grow everything. These organic butternut are a wonder; unlike giant pumpkins it is so sweet.
What's the difference between our easy butternut squash soup recipe and a supermarket butternut squash soup recipe? Chalk and cheese. I make no apology for the time spent in preparing food from scratch; it tastes and is far superior, preventing a awful lot more than just a beta-carotene deficiency.
Either you spend a few extra minutes on healthy choice foods, superior in taste in every way, or you'll spend a lot more time consulting doctors about your cataracts, high blood pressure, diabetes and many other even more serious diseases.
Growing zucchini is another of our favourites, particularly because they are also one of the few sources of two other very important phytochemicals for the eyes, lutein and zeaxanthin.
These are the plants from our garden that are what we call phytochemical foods; they supply the vast range of needed substances that you simply cannot measure; there are over 600 carotenes alone for example. Trying to keep a measure of them all will simply lead to what I call a health nut neurosis; and to be honest, it's a serious psychological condition that I myself have had to face; don't go totally overboard.
Your citrus fruit list is another excellent source of vitamins and phytochemicals that will prevent any suggestion of a beta-carotene deficiency. Whether it's lime marmalade or a mandarin orange tree, they all contribute.
Planting sweet potatoes is definitely only for the larger garden, but they actually top the list in the prevention of beta-carotene deficiency stakes. They don't keep as well as butternut and should be kept in the refrigerator and eaten fairly quickly.
Carrots of course are another excellent way to prevent a beta carotene deficiency; but raw or cooked?
Livny et al researched the question, comparing the bioavailability of beta-carotene from cooked and pureed vs raw and chopped carrots. Both in fact were a good source, but 50% more was absorbed from the cooked version of carrots.(2)