3 “Alternative Facts” About Diets and Nutrition

Forgive me co-opting “alternative facts”, the catchphrase popularized by President Trump’s advisor, Kellyanne Conway. I’ll leave political discussions to other blogs and – for those of you with a strong stomach – social media; I was amused by the phrase and thought it would be a new way to describe some myths and falsehoods in the fields of diet and nutrition. So here we go:

1. Increasing Blood pH Will Improve Your Health

I’m going to lead with this one because the quack who came up with it was just arrested in California for promising terminally-ill patients he could help them by alkalizing their bodies. Actually, that’s not true. He was technically arrested for practicing medicine without a license. Had he merely stuck with recommending the idea of eating specific foods to alkalize the body, he wouldn’t have been arrested at all. The premise of the Alkaline Diet is that acidity is the root cause of disease, and that through diet manipulation people can improve health and performance by making their bodies more alkaline.

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The problem is, the pH of arterial blood is tightly controlled in the range of 7.35-7.45, which is slightly alkaline compared to neutral pH of 7.0. Your body works very hard to keep it this way. The primary way you maintain blood pH is through breathing. Increasing acidity (higher H+ concentration) leads to increased CO2 levels in the blood (HCO3 + H+ <-> H2CO3 <-> H20 + CO2), which in turn drives an increase in breathing rate so you can blow off more CO2. When you hyperventilate you blow off too much CO2. Low CO2 levels shift the equation above to the right and cause blood pH to rise (become more alkaline). You become lightheaded and eventually pass out, at which point your breathing rate hopefully returns to normal and you regain consciousness. Another way you regulate pH is through the kidneys. The pH of urine can swing from basic to acidic depending on what the body needs to excrete to keep blood pH within the normal range.

The other problem with using diet to manipulate blood pH is that the stomach secretes acid and our digestive system is designed to break down anything we eat into a slurry compatible with absorption through the semipermeable membrane of the intestinal wall. Anything not compatible with the system keeps on moving until it gets excreted. In other words, your body has elaborate ways of maintaining the correct blood pH, which is good because if successfully alter it, you could put yourself in a coma (pH of 6.9) or die (pH below 6.8 or above 7.8).

2. Detox Diets and Cleanses Improve Health and Performance

This one is also timely because lots of people try counteracting poor choices with a post-Holiday Season cleanse or detoxification diet. The premise is that fasting or consuming a tightly restricted set of foods/drinks will purge toxins from the body. Again, evolution already gave us a superb way to do that: filtering blood through the liver and kidneys. Metabolic waste and even ingested pollutants that make it into your bloodstream are filtered out and excreted. Are there pollutants that don’t get filtered out? Yes, heavy metals like mercury and lead can collect in body tissues, and a juice cleanse won’t remove them either.

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What about fasting cleanses? Autophagy (eating oneself) is a natural process in cellular renewal. Existing cells are broken down and parts can be used for energy, recycled, or excreted. Prolonged fasting accelerates autophagy, as does exercise. Proponents of long fasts (more than a few days) claim autophagy improves health because it “cleans out” cells containing toxins so they can be replaced with fresh, new, toxin-free cells. You know what cells starvation-induced autophagy consumes first? Muscle cells. You break down muscle so the protein can be made into glucose in the liver via gluconeogenesis. Even if you’re not an athlete you want to avoid muscle wasting.

There are a few good things about detox diets and cleanses, though. They bring greater awareness to what a person is (or isn’t) consuming, and that typically leads people to start making better choices. They also significantly disrupt previous behaviors, and some people can successfully use them to “reset” their nutritional habits. But the best thing about cleanses is that they don’t last long. Not eating for a few days isn’t likely to hurt you as long as you are otherwise healthy and stay hydrated. Within reason, drinking only lemon water or some other concoction for a few days is probably harmless, too. But as I recently heard one of my coach say, “If something doesn’t improve performance, then the fact it isn’t harmful doesn’t suddenly become a good reason to do it.”  

3. Vegans Can’t Be World-Class Athletes

While it may be easier to be an omnivore and train and compete as an elite athlete, I haven’t seen compelling evidence showing plant-based diets prevent athletes from achieving maximum performance. People frequently express concern about vegan endurance athletes and adequate consumption of protein (muscle synthesis and immune function) and iron (key component of hemoglobin, which binds oxygen to red blood cells). First, there are plenty of plant-based sources of whole protein and amino acids, including essential amino acids that can’t be created by the body: beans, nuts, seeds, avocado, and quinoa are just a small sample. Second, the concern about iron is typically about the difference between heme and non-heme iron, found primarily in animal products or plants, respectively. The bioavailability of heme iron is higher than that of non-heme iron, which only means more of the heme iron you consume ends up being used by the body. As long as vegan or vegetarian athletes eat enough plants rich in non-heme iron (like green leafy vegetables), they can maintain normal iron levels in the blood.

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Where some vegans and vegetarian athletes (and any athletes, really) can get into trouble is restricting calories for weight loss and trying to support high-quality training while also consuming a lot of low energy density foods. Green leafy vegetables are high in nutrient density and low in energy density. They are filling and nutritious without delivering a lot of calories, whereas avocados, nuts, and seeds are both nutrient- and energy-dense. Consuming enough energy for productive training and adequate recovery requires focus. In some cases athletes need to at least consider why they are maintaining a vegan diet, which doesn’t necessarily improve performance, and whether those reasons are valuable enough to you to justify the focus required. For many, veganism is a lifestyle commitment and that’s fine. For others, incorporating a select few animal products (fish and/or eggs, for instance) can provide some flexibility that makes it easier to meet their energy requirements.