This week, I spoke with Eric Williamson, nutritionist and PhD student of exercise science at the U of T’s Faculty of Kinesiology and Physical Education, to find out what we should be eating to optimize our health and boost immunity. Along the way, I poked at all the bears: vitamin supplements (are they necessary?), weird diets and the mysterious transformation in which foods that are Very Bad For You become superfoods.
What do you wish people knew about nutrition?
One thing I wish people would keep in mind about nutrition is that consuming whole foods and exercising regularly has the largest impact on our health. That should guide all our decisions. There are a lot of things you hear talked about which don’t make as much of an impact. If someone’s trying to maximize their intake of a particular nutrient or manipulate their hormones, I’d just like them to keep in mind that however they go about those goals, they shouldn’t ever sacrifice having whole foods a majority of the time or regularly exercising. If what they’re doing is impeding on either of those two things, it’s probably not worth it.
Why whole foods?
We’ve evolved on whole foods, for one. And they contain a lot of nutrients. You’re highly likely to obtain sufficient micronutrients that way. They’re also high in fibre, which is very important. If we’re consuming whole foods, our body is able to adapt to minor differences in certain nutrients. One of the things that’s most hotly debated today is high fat versus high carbohydrate diets. The average person’s body is very adaptable to whether we’re consuming either of these as long as they are consumed mostly from whole foods.
What would you say about vitamin supplements?
The definition of a supplement is that which is taken in isolated form which cannot be obtained in sufficient amounts through diet. This being said, if somebody is not able to consume foods that are high in a particular vitamin or mineral, or they have a deficiency that’s been medically diagnosed, that would warrant taking a supplement. But for the most part, we do want to take a food-first approach, to see if we can get most of it through food, if not all of it.
For example, most people are going to be able to consume enough vitamin C through food, as long as they’re consuming a sufficient intake of fruits and vegetables. If you take a vitamin supplement on top of that, you could be going overboard. Vitamin C is a very powerful antioxidant. For the average person, it’s a waste of money. But for an athlete who’s taking vitamin C supplements as well as consuming enough through food, it may have such an anti-inflammatory effect that it inhibits the recovery process after exercise. This is where we want to be careful with supplements.
Another example is iron. Not everyone should take iron supplementation. We can get it through food. Iron deficiency can be diagnosed through a blood test. Only if they are showing signs of deficiency should people potentially take a supplement and they should speak with a health care provider before doing so.
On the other extreme, we can make a pretty good bet that our population is deficient in vitamin D. In the winter months, from around October to April, we’re too far away from the sun. Because of this, we need to obtain it through supplement form. There are some foods that are fortified with it, like milk. Even if you’re getting it through food, the risk of taking extra vitamin D is quite low. It’s difficult to get too much with supplements over-the-counter, so the majority of people in Canada should take a vitamin D supplement to make sure they’re getting enough.
How would someone go about finding out how much to take?
I’d say you’re better off taking 1000 IU vitamin D than not taking it, because the risk of going overboard is low, whereas the risk of deficiency is very high.
We see that those who are consuming a sub-optimal level of vitamin D have a reduction in strength and power [when they exercise], and a reduction in immunity. There’s an increase in the common cold.
Do darker skin tones need more vitamin D?
It’s not that they need more vitamin D, but during the summer months, they’d need more time in the sun. A very pale individual can obtain enough sunlight for their body to synthesize adequate amounts of vitamin D in fifteen to twenty minutes per day. Someone who is more medium-toned might need an hour or so. A very dark individual could need as much as two hours. So everyone needs the same amount of vitamin D per day. But the body doesn’t synthesize as much from darker skin so they need to spend more time in the sun.
About whole foods: do you have any procedure for washing fruits and vegetables, since they come covered in pesticides?
If we look at the scientific consensus on pesticides, the risk is very low. The amount that’s allowed to be detectable on produce is less than 1/100th of what’s been shown to produce harm in animal models used in research. Just washing with water eliminates most of the pesticides and the risk of any adverse effects of pesticides currently on produce in Canada is low.
Why does a food that was formerly bad become a superfood? (Eggs, coconut oil, etc.)
What I like to tell people is that science doesn’t change. What changes is our interpretation of the data. The media can be very sensationalist. Scientists are trained to be very careful with what they say, but journalists sometimes are not. We’ll never say the data “proves” anything, we’ll say it suggests something.
Nutrition as a science has been around for less than a hundred years today. Compare that with the physical sciences that have been around for thousands of years. We don’t know very much and that’s really hard for people to admit, because we want certainty. At the same time, we know a lot, but we don’t know everything which is why our interpretations can change with new evolving evidence.
So do we just ignore facts changing in the news?
This has always been something I’ve struggled with: how to teach the public an effective way of navigating interpretation of science and media reports. As a start, always check that there are references to academic articles. Also, hold it up against those big rocks we talked about- make sure it doesn’t interfere with whole foods or exercise. And if it doesn’t make sense from an evolutionary standpoint, I’d be sceptical of it. Lastly, find someone you trust that has knowledge in the area and can put these reports into context for you, if you’re considering changing the way you eat based on something you’ve read or heard. Having a professional who can add context is critical for determining if the recommendations implied by the report, which is often based on “averages”, is appropriate for you.
How can we boost immunity?
What makes the most difference with regard to immunity is hand washing. Also, not over or under exercising. A sedentary lifestyle means higher risk. And if you’re over-exercising and causing yourself so much stress that you’re unable to recover well from your exercise, this can also increase your risk. Eat whole nutritious foods, especially lots of plants. Adequate protein is also important for immunity, so make sure you have some source of protein at every meal and snack.
A very large portion of our body is made up of protein. When we consume it, we’re replacing the protein currently in our tissues, and also proteins important to many physiological processes like the antibodies of the immune system. Having a high source of protein at every meal and snack will help with this, keeping our tissues “fresh” and functioning optimally.
Do nuts and seeds have a higher level of protein?
Yeah, but they’re a fat-based food. Don’t go to nuts for your protein, consume them for healthy fats, vitamins and minerals. For protein, go for sources such as beans and legumes, soy, tofu, lean meats, seafood and dairy, like cottage cheese or Greek yogurt.
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