Kale Won’t Kill You & Sugar Isn’t Poison: Ignore Silly Food Claims About Harm

The dosage makes the poison.

“Sugar is poison.”

That is one of several absurd claims made on social media by coaches, trainers, and even some healthcare providers.

It’s not.

Can sugar be harmful? Absolutely.

Do you know what else is potentially harmful?

Water.

You can die from ingesting too much water, cleverly known as water intoxication. It has happened to athletes in the midst of training or competing.

Does that make water poison? No.

For a 75kg person, you need to consume 6 liters of water in less than 3 hours to suffer from water toxicity.

You can’t ignore the volume of consumption.

The Dosage Makes the Poison

The next time you read a headline or hear someone claim a food item is toxic or poisonous to use, you should be skeptical.

A prime example is how the carnivore crowd attacks vegetables.

The claim is plants develop defense mechanisms for protection, therefore, those chemicals are harmful to us.

We are slightly larger than bugs, birds, and most plant-eating animals those plants are concerned about.

Layne Norton provides a prime example.

He reviewed a claim that kids vitamins are toxic because they a contain compound — cyanocobalamin — that is synthesized from hydrogen cyanide. This compound is a manufactured version of vitamin B12. But clearly, the cyanide part is going to harm you, right?

They have tested the compound in rats to test the dosage needed to cause death. How many cyanocobalamin pills would humans need to take to reach toxic levels? Take a guess.

33….thousand!

Yes, biologies differ and there are more side effects than death. Even the lowest end of potential toxicity is 2500 capsules.

That’s a lot of Flinstone vitamins.

The dose makes the poison

This is a vital concept that originates from the field of toxicology, which is the study of the effects of chemicals and substances on living organisms. The concept suggests that any substance can be toxic if the dose or exposure level is high enough, even if the substance is typically considered safe or beneficial at lower doses.

In the context of nutrition research, the concept of “the dose makes the poison” can help us understand why certain foods or nutrients may be demonized or promoted as “superfoods” without taking into account the appropriate dosage or context.

One example of this is the recent demonization of carbohydrates in popular diets, such as the ketogenic diet. This is where the sugar is poison claim often comes from.

While it is true that excessive consumption of refined carbohydrates can increase the risk of obesity, diabetes, and other chronic diseases, it is important to recognize that carbohydrates are also an important source of energy and essential nutrients for the body. Furthermore, carbohydrates come in many different forms, ranging from refined sugars to complex carbohydrates found in whole grains and vegetables, and the effects of these different forms on health can vary.

Unless you consume raw organ meat or a bucket of vitamins, you will be deficient in key vitamins and minerals avoiding plants.

You need fiber as well. It is integral for gut health.

Soluble fiber forms a gel-like substance in the stomach which slow digestion, helping control blood sugar and cholesterol, like a metabolic sponge. Insoluble fiber adds bulk to stool and improves regularity. It also helps regulate insulin.

We start to see substantial health benefits — lower body fat, improved glycemic response and reduced blood pressure, triglycerides, and low-density lipoprotein cholesterol (LDL-C) — once crossing the 25–30 gram per day threshold.

Take the vegetable Kale, which tops nutrient density charts (number of nutrients per calorie).

Kale, along with other cruciferous vegetables, is being attacked in some circles over the fear of heavy metal poisoning. Once again, the dosage makes the poison.

First, finding high levels of heavy metals in kale is rare. The original study only found high levels of heavy metals in kale planted in soils with high concentrations of thallium.

The study has never been replicated. This is a case of taking a single study and blowing it way out of proportion. The study didn’t establish a dose-response for toxicity either.

Our bodies have great mechanisms for eliminating heavy metals and other toxins. Unless you are planting kale in heavy metal-rich soil and consuming multiple Kale salads a day, you don’t need to fear.

Kale and other vegetables are net positive for your health.

Another example is the demonization of fat in the 1980s and 1990s, which led to increased consumption of low-fat and fat-free foods that were often high in sugar and refined carbohydrates. While it is true that excessive consumption of saturated and trans fats can increase the risk of heart disease, it is important to recognize that not all fats are created equal.

Healthy fats, such as those found in nuts, seeds, avocados, and fatty fish, have been shown to have potential health benefits when consumed in moderation.

Even saturated fat will have a dose-response. Having an occasional steak will not lead to heart disease. Having red meat on a daily basis will increase your risk.

Anything can be harmful if consumed in excess.

We also need to avoid tunnel vision when evaluating food.

Nutrition is Complex

Let’s build off of the dosage conversation.

Take a piece of steak. Depending on the cut of steak it will have varying amounts of saturated fat. Does this alone mean steak is bad for you?

You aren’t working with all of the information.

Steak is a great source of protein and it contains high levels of vitamins B6 and B12, iron, zinc, and niacin. These are all positive for overall health. If you cook a lean cut of steak (e.g., top sirloin) will just salt and grapeseed oil (good for high temperatures), I would lean that steak on the healthy side of the meter (food is not healthy or unhealthy, it’s a gradation).

Conversely, if you choose prime rib and douse the meat in oil and butter, the calories and saturated fat skyrocket, pushing the food more to the unhealthy side.

You also need to consider your wiggle room.

If you are metabolically healthy and you limit your red meat intake to 1 or 2 times a week, that steak will have little to no effect on your cholesterol levels. If you have cheeseburgers daily, that could be problematic.

You can play this game with every food.

Look at the whole picture.

Eat Your Veggies

There isn’t an ideal dietary pattern.

There are, however, some dietary habits that are clearly linked to health.

A 2021 meta-analysis provides a great foundation to build off. As you will see, you have a lot of options for healthy dietary patterns.

The review included studies that enrolled adults and older adults (aged 17–84 years at baseline) from 28 countries with high or very high Human Development Index. Of the 153 studies included, 53 studies originated from the US.

Most of the studies were well-designed, used rigorous methods, and had low or moderate risks of bias. While nearly all were cohorts (1 randomized trial), that is the best design for assessing population trends and outcomes.

Cohorts are limited in their ability to determine causation. You have likely hear the phrase ‘correlated does not equate causation.’ This is true but it doesn’t mean a correlation is not a cause-and-effect relationship.

Some relationships cannot be tested with trials due to feasibility (number of recruits needed or ability to design randomized controls) or ethics. For example, you can’t design randomized trials for smoking.

Imagine proposing a study to an ethics board stating you will randomly assign 1000 people to a smoking group with real cigarettes and 1000 people to a placebo group with fake cigarettes and wait to see who accumulates more deaths.

Not going to happen.

That doesn't mean we haven’t figured out smoking is extremely harmful. When dozens of cohorts show people who smoke more develop lung cancer and people who stop smoking reduce lung cancer incidence, you start to develop a picture of causation.

When we combine that data with mechanistic data, looking at the specific effects of smoke inhalation and nicotine on tissues of the body, through a combination of animal studies, tissue samples, and autopsies, the picture becomes clearer.

That is what is happening with dietary patterns.

It’s never a clear-cut effect as sleep, exercise, genetics, and psychosocial factors all influence our health. If you sleep well and exercise regularly, you have more wiggle room in your diet.

There is a lot that can be said about the psychosocial and contextual factors of diet. Perhaps I will address those another time. For now, let’s get back to the healthy dietary patterns.

The results across the 153 studies were highly consistent.

Evidence suggests that all-cause mortality is lowest for people that consume high levels of vegetables, fruits, legumes, nuts, whole grains, unsaturated vegetable oils, fish, and lean meat or poultry.

The healthy eating patterns were relatively low in red and processed meat, high-fat dairy, and refined carbohydrates or sweets.

Translation? Eat more plants and limit ultra-processed foods and meats high in saturated fat.

These recommendations are consistent with other data. These healthy dietary patterns promote high levels of fiber and micronutrients, moderate to high levels of protein and unsaturated fat, and low levels of saturated fat and added sugars.

As I have written about previously, there are several markers of health that are consistent in the literature: muscle mass, strength, VO2 max (aerobic capacity), BMI, LDL, A1C (glucose levels)

The healthy eating patterns mentioned above will support all of those health outcomes.

Nutrition is both simple and complex.

There are many ways to eat healthy and it largely involves eating whole foods.

The next time you hear a claim that a single food item is toxic or poisonous, find out the sources behind the claim. Usually, the claim can be safely ignored.

If you focus on the big picture eating patterns, you can ignore the noise spread by influencers and the media.

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