Picture the scene. Your baby is six months old, and is growing healthily and happily on your breast milk alone.
You're starting to introduce other foods in line with guidance from the World Health Organization and the UK's own Department of Health.
But during a routine visit to your clinic, the health visitor says you aren't doing enough to protect your baby's health. Now that he's six months old, you're told, he needs extra vitamins because your milk is 'too low' in vitamin D.
Currently in the UK, breastfed babies aged six months and over are deemed to be at risk of rickets - a serious developmental disorder that results in, among other things, abnormally weakened bones.
The main cause is a lack of vitamin D. Calling this a 'vitamin' is a misnomer - it's a hormone produced in the body after exposure to ultraviolet B (UVB) rays. It's also present in some foods (including breast milk), but most of the vitamin D we use comes from sunlight.
Breastfeeding mothers in the UK are routinely advised to give vitamin D supplements to their infants after six months. In the US, the advice is to start even younger - in the first two months. Formula-feeding mothers are 'exempt'.
This is all rather puzzling. Could Mother Nature have got it so wrong?
The truth is, it's not breast milk that's deficient, but modern-day lifestyles which, at their worst, may mean that babies are deprived of their birthright - sunlight.
As American researcher Cynthia Good Mojab says, 'The direct, casual exposure of skin to sunlight is the most common and biologically normal way that human beings attain sufficient levels of vitamin D' (Mothering, 2003; 117: 52-5, 57-63).
We do our babies a major disservice when we wrap them up and bundle them off from house to car to nursery to indoor shopping mall and back home again.
But, in fact, most of us don't do anything like this. Most babies do get sunlight on their skin just by being out and about. In one study carried out in Cincinnati, Ohio, just 20 minutes a day out of doors with exposed hands and face were enough to maintain satisfactory vitamin D levels in older infants.
Time spent outside on most days should be enough to ensure that all babies can make their own vitamin D, including babies whose skins are black or brown and living in Northern European climates. The melanin pigment in their skin protects them against damage from strong sunlight so, compared with light-skinned babies, they may need more time under the weaker, British sun to get what they need.
There is evidence that some toddlers from Asian backgrounds may benefit from supplemental vitamin D; some paediatricians report cases of rickets among unsupplemented, breastfed Asian toddlers, but the numbers are extremely small, and other dietary and lifestyle factors have not been examined (BMJ, 1999; 318: 39-40).
One survey of Asian two-year-olds showed that up to a third had vitamin D blood levels designated as less than adequate, though all were healthy and none had rickets (Eur J Clin Nutr, 1999; 53: 268-72).
Prevention of vitamin D deficiency lies behind the current blanket recommendations in the UK, which don't apply to non-breastfed babies as the vitamin supplements are added to the formula as part of its processing.
So, given that I don't want any baby to suffer from any sort of nutritional deficiency, why would I question the current official recommendations?
Here's why. Any advice given to everyone across the board, regardless of individual circumstances and without providing full background information, is bound to have drawbacks.
The biologically and physiologically normal way to nourish infants is to breastfeed, with the addition of an increasing quantity and variety of solid foods as the baby gets older. It's also normal for infants to spend some time outdoors on most days, except in the coldest weather.
Why not ask mothers how much time they spend outside with their baby? Why not find out if their lives incorporate occasional visits to the shops or the park? Some women - not just Asian mothers - may spend a lot of time isolated indoors; their babies may be left in poor-quality nurseries; there may be other specific circumstances that prevent some children from getting the sunlight they need.
Targeting the judicious use of supplements at families who actually need them makes far more sense than worrying the families who don't. It also avoids any further undermining of breastfeeding, already under pressure in a bottlefeeding culture.
Vitamin D supplements are given in drops which also contain vitamins A and C - and there is no evidence that these additional vitamins are necessary for any breastfed baby but, because they come as a 'package deal' with D, babies end up getting them anyway.
As Good Mojab says, 'When rickets occurs in breastfed infants, it indicates that something is very wrong with the context in which breastfeeding is happening, not with breastfeeding itself. Social and environmental problems in that context warrant assessment, further research and amelioration.'
Heather Welford is a freelance journalist and writer as well as the author of several books on infant feeding. She is also a breastfeeding counsellor and tutor with the National Childbirth Trust.