I am a graduate student in nutritional science at Iowa State. Following Edan Lambert’s response to your opinion piece “Hays: Eat Less Meat,” I would like to offer the food science and human nutrition perspective. Your claims are worrisome and misleading, so I would like to fill in some missing details.

Your statement “everyone should cut as much meat out of their diet as they can” followed by contradictory statements that this is nearly impossible and causes health problems is confusing. Indeed, there are benefits to plant-based diets.

However, I am concerned your article did not communicate associated risks. Improperly managed plant-based diets can lead to life-threatening nutrient deficiencies, and resulting diseases such as osteoporosis, various anemias and morbidities. Sharing information which potentially impacts health status should use evidence-based information.

Consider the Beef in an Optimal Lean Diet (BOLD) study, in which participants were given a controlled diet to monitor changes in blood lipids. Researchers found replacing carbohydrates with animal protein (including lean-beef) and low saturated fat foods significantly decreased total cholesterol and low-density lipoprotein (LDL) cholesterol, major risk factors for heart disease.

This corroborates hypotheses that eliminating lean red meat does not decrease mortality but can increase it. Highly restrictive diets, such as vegan diets, are challenging to follow long-term and do not necessarily include healthy choices.

The American Heart Association discusses benefits of animal protein in a heart-healthy diet. Poultry and eggs are complete proteins, sources of both essential fatty acids (omega-3 and 6, which must be consumed in the diet) and are accessible and affordable. Uniquely, eggs provide every essential nutrient except fiber and vitamin C. 

It’s noteworthy that all essential nutrients (fatty acids, amino acids, vitamins and minerals), with the exception of carbohydrates, are more easily absorbed (bioavailable) when consumed from animal sources.

For example, 25 percent of iron consumed from animal sources is directly absorbed. Alternatively, only 3 percent of iron from plant sources is absorbed. You mentioned iron (which is a mineral, not a vitamin) “increases energy and strengthens blood flow.”

Neither is true. Iron is non-caloric, so it cannot provide energy. The primary function of iron is transporting oxygen in the blood, not regulating blood pressure.

Calcium is also of concern for individuals following a vegan diet.  One cup of milk contains approximately 300 mg of calcium; a person would have to eat 32 cups of raw spinach based on MyPlate portion sizes. 

I am unsure what you mean by “vitamin B₃ [niacin] helps break down [macronutrients] into healthy energy.” Metabolism involves every B-vitamin, not just niacin, and every essential amino acid, some of which are difficult to obtain in a plant-based diet. Furthermore, niacin deficiency isn’t concerning. What is concerning is vitamin B₁₂ deficiency, as B₁₂ is only found in animal sources. If unmanaged, B₁₂ deficiency is lethal.

Rather than continue, I would echo Edan’s statement that fear-mongering is not “a fair or productive way to engage in conversation.” Iowa State University is a research institution. As researchers, we strive to find the truth and we openly welcome discussion, particularly when it involves differences in opinion.

When questions are raised, discoveries are made. I urge you to take advantage of the exceptional resources you have right in front of you. Human and animal scientists, environmental, soil and crop scientists, global resource scientists, human and animal nutritionists, and registered dietitians would all be glad to hear your concerns and share their knowledge with you. 

Please feel free to contact me:

Julia Lavallee

[email protected]