Plant-based Milks and Kids’ Growth
Over the last few days there’s a Canadian study getting quite a bit of media attention, primarily because it found that at age 3, kids who drank the most cow’s milk are on average 1.5cm taller than kids who drank the most plant-based milks. Any suggestion that dietary choices impact children’s growth and development is of course going to be of great interest to the general public and unfortunately has the potential to generate anxiety and concern, particularly for parents who are raising their children on a plant-based or vegan dietary pattern.
Apparently there are several methodological weaknesses to the study. To be fair these are always present in any research. But these do include neglecting to account for the kids’ overall diets and the heights of their parents. So from the get go we’re looking at a couple of fairly obvious and fundamental confounders that were not controlled for. I’d rather look at the study for myself before getting too hung up on this kind of thing, but it’s already sounding like it wasn’t particularly well designed.
Also concerning is the fact that the lead author of this study has accepted grants from the dairy industry in the past, at the very least to the tune of about $90,000. Furthermore, he’s been a member of an advisory committee to the dairy industry. Of course we all come into science with our own bias. But it frustrates me enormously that there’s so much industry influence and that so many researchers seem not to see this as an issue.
We could argue all day about to what extent these ties would or would not have influenced his findings. However, we know that any industry ties whatsoever are not a good idea if impartial results are the aim (presumably industry didn’t fund those studies!) I’m sure the lead author is aware of this. So why take these kinds of grants in the first place? Call me an idealist but I feel that the purpose of scientific research is to help forward our knowledge, not to line one’s pockets or to generate publications to pad one’s résumé. If no-one other than industry wants to fund your research then I’d suggest taking a long hard look at the questions you’re asking. If anything we have much too much research being published nowadays, so if that means the bar is raised a little higher for getting funding, I’m very ok with that.
I’d also like to see whether they controlled for length of breastfeeding. We know that kids who are formula fed grow faster than children who are breastfed, for example (https://www.ncbi.nlm.nih.gov/pubmed/16902325). This raises a fundamental flaw with the suggestion made by researchers (and certainly by the media) that the cow’s milk children were ‘healthier’ than those who drank plant-milk. Please stand up anyone who thinks that formula feeding is a better idea than breastfeeding! So it would be ludicrous to conclude that breastfed babies are less healthy or that their growth is ‘stunted’ in comparison to formula fed babies.
When I first read the result though, I was not at all surprised. There’s a good reason why kids who drink more cow’s milk would be taller or growing faster, and that reason’s likely to be insulin-like growth factor 1 or IGF-1 as us medical types refer to it. Indeed, in the aforementioned publication, it’s noted that:
“Formula-fed infants at 4-5 months of age show higher plasma levels of insulin-like growth factor-1 (IGF-1), insulin and certain amino acids than breast-fed infants. Whereas the protein intake of breast-fed infants decreases with age and closely matches the requirements for protein during the early months of life, the protein intake of formula-fed infants exceeds requirements after the first 1-2 months of life.”
So basically there’s something about cow’s milk, that likely has at least something to do with the protein content (noted here to be in excess of what’s necessary), that amps up kids’ IGF-1 and gets them growing more quickly. But is this good or natural? Certainly not. You’re welcome to check out nutritionfacts.org to learn about the many reasons why, but as an example one of the videos is titled ‘IGF-1 as One-Stop Cancer Shop’.
While of course IGF-1 is a hormone produced by the body naturally that helps kids grow, increasing their levels of this by consuming the protein and hormone-laden milk of another species seems neither natural nor health promoting. Consider also that dairy consumption has been linked to type 1 diabetes, acne, anaemia, premature puberty, diminished male reproduction, Parkinson’s and Huntington’s disease, and prostate, breast, and ovarian cancers. And that a side effect of the dairy industry is rapidly destroying the very world that our kids stand to inherit. In New Zealand it has already ruined many of our formerly pristine and beautiful waterways. Taking these facts into account I’d suspect cow’s milk consumption would not be habit parents would want to encourage.
As a final point, I think it’s important to say something about plant-based milks. Similar to their cow milk counterparts these are quite processed and really do not provide anything particularly useful for kids nutritionally. Kids and parents in my experience often habitually over-rely on milk as a source of energy. If something useful is to come from this study, it may be that it provides a reminder to parents of plant-based kids about this.
Keep in mind that there are large amounts of energy in both cow’s milk and plant-milk and that because of this a glass of milk is never a particularly good idea, whichever animal or plant it’s from. Children simply should not be consuming 3 cups of plant-milk a day as some of them were in this study. When they do this it means they’re getting a substantial amount of their energy for the day from a processed food and by necessity missing out on getting a bunch of other nutrients that will help keep them healthy and growing.
Given the average energy needs of a child aged 3, those 3 cups of soy milk would have supplied just under 40% of their required energy intake for the day. So another way we can look at the results of this study is to be thinking about what might happen to plant-based kids’ growth when they’re getting large amounts of their energy from highly processed and rather nutrient deficient sources.
Because kids have little stomachs, they get ‘full’ more easily and so it’s ideal, particularly on a plant-based diet to ensure they are getting the best kinds of foods as well as plenty of energy to get them through the day. The smartest way of doing this will involve putting the plant-milks aside (just use with cereal or for recipes if you like) and concentrating on whole, minimally processed foods from plants. Kids may require more energy dense plant foods from time to time than adults do, but there’s avocado, nuts and seeds, coconut, and even dried fruit to help with that. If you feel like they really need a drink with some energy in it then a smoothie is much more fun and tastier than a glass of plain old almond or soy milk anyhow and has the added bonus of packing a better nutritional punch (you may even be able to sneak a few greens in!)
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