Dispelling nutrition myths, ranting, and occasionally, raving


13 Comments

Is milk out?

I’ve been hearing a number of complaints and concerns about the new Food Guide. The one I’ve been hearing the most is that “dairy is out”. I’d like to dispel that. No, dairy is not “out”. Yes, the “milk and alternatives” food group is gone; as is “meat and alternatives” but milk and dairy products still fit within the protein group in the new guide.

The Food Guide now recommends a proportion-based approach to eating, rather than a more prescriptive portion-based approach. Rather than telling you how many servings of each food group to have every day, and how big a serving is, the new guide simply advises you make half your plate vegetables (and fruit), one quarter protein foods, and the other quarter whole grains. It promotes consuming plant-based protein foods “more often”. This is pretty subjective and should – in theory – make it a lot easier for people to adopt. For some people this may mean consuming plant-based protein foods in larger amounts than animal-based proteins. For others, this may mean consuming plant-based sources of protein more often than they usually do. In a country that’s extremely meat-centric this could mean something as simple as adding more beans to a chili and cutting back on the meat slightly.

I’d also like to point out that given that a quarter of your plate should be devoted to protein foods you can easily mix and match to your heart’s content. This might mean that you have lentils and salmon (like I did last night), cheese and bean casserole, tofu and chicken, etc. It might mean that at one meal your protein comes from milk or meat but that at another it comes from legumes or nuts. Snacks can (and generally should) also include a source of protein. If you eat three meals and two snacks a day this means that there are ample opportunities for you to consume protein from a variety of foods, including milk products if you desire.

Personally, I think that having a food group specifically for milk (and alternatives) was unwarranted and I’m glad to see it go. There are many people who can’t consume milk products (due to lactose intolerance or an allergy) as well as those who choose not to and it is entirely possible to consume a nutritious diet without the inclusion of milk. For those who are concerned about where people will get their vitamin D and calcium from without milk products there are other food sources of these nutrients.

Vitamin D is pretty near impossible to consume enough of through food sources alone anyway, at least during the winter months in Canada and Health Canada recommends all adults over the age of 50 take a supplement of 400 IU/d. I’d also like to point out that milk is fortified with vitamin D as are most plant-based milk alternatives (always check the label to be sure). Other food sources of vitamin D include: egg yolks, salmon and other fatty fish, some meats, and other fortified foods which may include things such as orange juice and cereal.

Non-dairy food sources of calcium include: dark leafy greens (like spinach, collards, and kale), soy beverage, canned fish (eat those bones!), tofu (if prepared with calcium), beans, nuts, seeds, and even blackstrap molasses.

If you are concerned that you may not be meeting your nutrient needs through your diet I recommend keeping a food journal and making an appointment with a registered dietitian.


Leave a comment

The vitamin D debate: Won’t someone please think of the children?!

url

The latest “study” on vitamin D reached the conclusion that vitamin D does nothing to prevent myriad medical conditions. You may be wondering why I placed study in quotation marks. That’s because it’s not actually a new study. It’s an analysis of the results from a number of randomized controlled trials of vitamin D supplements.

Of course, there are the usual issues with meta-analyses. We don’t know for certain if the authors cherry-picked the studies they chose to look at. We don’t know (without spending substantial amounts of our own time, and probably money) if the original studies were flawed. It’s a good thing that it’s good that this analysis looked at studies using a randomized control model. This avoids the obvious potential confounding factors seen with observational studies. However, I have some doubts that these studies would have been conducted over long enough time-spans to accurately assess the use of vitamin D supplements. After all, they were looking at the effects of vitamin D supplementation on myocardial infarction or ischaemic heart disease, stroke or cerebrovascular disease, cancer, total fracture, hip fracture, and mortality. To truly determine the effects of vitamin D supplementation on these conditions supplementation would have had to begin in childhood and continue until death (or at least very old age).

The authors found that vitamin D did not affect outcomes by more than 15% for any of the above conditions, aside from hip fractures in institutionalized seniors.

I’m inclined to think that we may be expecting far too much from vitamins and minerals. Just because vitamin D probably doesn’t prevent cancer or heart disease doesn’t mean that there aren’t any benefits to be obtained from taking it as a supplement. Perhaps it may prove to be beneficial in mood regulation, cold prevention, or something else less earth shattering than these studies looked at.

Perhaps there is no benefit to taking vitamin D supplements. However, I’m not quite ready to toss my bottle. I know that I can’t meet the currently recommended amount of vitamin D through diet alone. And I’m certainly not getting any from sun exposure this time of year. I don’t think that we should dispose of the current vitamin D recommendations on the basis of one meta-analysis. I’m certainly open to changing my mind but for now I’d like to hedge my bets. I’d rather risk taking a “useless” vitamin D supplement than risk experiencing adverse health consequences from not consuming sufficient vitamin D.

In addition, I worry that research such as this may lead to new parents neglecting to supplement their infants with vitamin D and causing a resurgence in rickets. Just because there’s uncertainty about the long-term outcomes of vitamin D supplementation doesn’t mean that we don’t know the benefits in early childhood.


Leave a comment

Strong bones

Last week a US government advisory group announced that there is no benefit for healthy “older” women to take low-dose calcium or vitamin D supplements. These conclusions were based on findings that these supplements do not appear to reduce the risk of broken bones.

There are a few important things to note about this pronouncement: 1. This message applies only to healthy older women. Women who are suffering from certain illnesses may require more of some nutrients and should consult with their doctor before stopping (or starting) any supplement regimen. 2. The advisory group did not look at higher supplement doses. There may be benefits (or risks) to consuming higher supplemental doses. 3. The announcement was based on risk of broken bones in comparison to risk of kidney stones. The advisory group did not look at any benefits of supplementation other than bone health. There may be additional benefits to vitamin D supplementation (again, or risks) we just don’t have sufficient research to advise on this basis yet.

I think that the most important lesson we can take away from this study is that many illnesses that befall us when we’re elderly are a result of exposures and lifestyle during our youth. As I remember learning in school: osteoporosis is a pediatric disease with geriatric consequences. We can’t mistreat or neglect our bodies when we’re young and then expect to make up for it when we’re elderly. To ensure strong healthy bones as seniors we need to ensure that children and young adults consume healthy balanced diets; including adequate vitamin D (which may require supplementation) and calcium. Children also need to engage in regular physical activity and we need to continue to exercise throughout our lives to maintain muscle mass and strong bones.

While it’s never too late to start leading a healthy life, it’s also never too early.


Leave a comment

Is the sun setting on vitamin D?

Researchers in Germany recently found that higher maternal levels of vitamin D during pregnancy translated to higher in utero levels of vitamin D for their babies. This in turn, was associated with greater likelihood of developing a food allergy by age two. This is interesting because vitamin D is one of the few supplements I advise pretty much everyone to take, at least during the winter months, as it’s highly unlikely that most of us are meeting the current recommendations via food consumption.

Looking at the original journal article, I couldn’t find any listed source of funding. Always the first thing I check when I’m looking for legitimacy of research. Next I checked to see how many participants there were, and how they were selected. There were 629 mother-child pairs, not too shabby. Participants were recruited from an existing cohort study entitled LINA (Lifestyle and environmental factors and their Influence on Newborns Allergy risk). I’m not sure how participants were recruited from the study, nor am I sure how participants for the original study were recruited. I can’t help but wonder if they were volunteers if there might be some selection bias that would skew the results. However, further along in the methods, the researchers state that the vitamin D levels were tested for 378 mother-child pairs. This is still not a bad sample size, but not nearly as good as it initially appeared.

Getting into the statistical analysis makes me wish I had cared more about learning and retaining statistical ability when I was in school. It’s interesting to note that vitamin D levels were strongly correlated with season. Maternal and cord blood levels of vitamin D peaked in August and were lowest in March. Also, only seven of the mothers took vitamin D supplements during pregnancy. 44% of the mothers were deficient in vitamin D, 26% were insufficient, and 30% had optimal levels. 50% of newborns had deficient levels of vitamin D.

Results were analysed by dividing the mother-child pairs into quartiles based on the mothers’ vitamin D levels. I find this a little suspicious. There are no details provided as to how many mother-child pairs were in each category, nor what the cut-off were for each quartile, and I’m not sure how fair it is to draw comparisons between the quartiles if the distribution (as was mentioned in the analysis) was not equal. The results do show significantly more diagnosed food allergies among children born to mothers in the 3rd and 4th quartiles (i.e. those with the highest blood levels of vitamin D during pregnancy). However, there were still only six in the 4th quartile and five in the 3rd, compared to three in the 2nd and one in the 1st. It’s also important to note that the “diagnosed” food allergy was reported by the mother on a questionnaire; diagnosis was not actually obtained by the researchers. This introduces an additional element of bias.

In the discussion the researchers acknowledge that there was a high level of participation from allergy sufferers which may mean that the results can’t be generalised to the entire population.

Because vitamin D levels were so strongly correlated with the seasons I wonder if there is some other seasonal factor which may be causing the increased rate of food allergies among the children. There may also be some other commonality among the mothers with higher levels of vitamin D which is leading to increased rates of food allergies among their offspring.

I do think that this research is interesting and warrants further investigation. However, I worry that studies like this may actually cause more harm than good. Vitamin D supplements for infants are important to avoid the development of rickets. I wouldn’t want any potential parents, or new parents, to interpret these findings as an indication that they shouldn’t be providing these supplements to their babies.

 

Thanks to one of my loyal readers for sharing the news article with me and for one of my twitter friends for hooking me up with the original journal article.


Leave a comment

Follow Friday: Vitamin D

I’m not going to lie; when I clicked on the link in the tweet from @fitocracy I was hoping to find some fodder for a blog rant. The tweet read: “Vitamin D: 3 Things You Probably Know, 3 Things You Probably Didn’t”. Fortunately, I was pleasantly surprised by a seemingly accurate article about vitamin D written by the founders of the website examine.ca which is a science-based site about supplements and nutrition.

If you’re interested in learning more about vitamin D, or just curious to find out if you already know it all, you should check out this article.