What Happens When Substituting Plants for Animals?

Popular wisdom holds that we should be substituting plants and for animals in the sources of our food. The reasoning comes down to impact on the environment and arguments for reducing saturated fats in our diets. Much of the writing on this subject – even in scientific journals – comes from a perspective of advocacy. So we are grateful to read a more dispassionate accounting in the August issue of the Journal of Nutrition.

Marion Salomé and colleagues analyze of the nutrition effects of replacing meat and dairy products with plant-based substitutes. Those effects on diet quality is generally small, but they can vary. It all depends upon the details of the substitutes.

A Detailed Look at Overall Dietary Quality

These researchers simulated the effect of substituting products from plants instead of animals on the whole of a person’s diet quality. This differs from typical comparisons, as the authors explain:

“The issue of the nutritional quality of plant-based substitutes is usually addressed by comparing the nutrient contents of food products, often with information on a reduced set of nutrients and not taking account of the frequency and amounts consumed or the importance of nutrients to public health. By contrast, our study offers an integrated quantitative assessment of the true expected impact of such changes at the level of whole diets.”

Thus, they found that promises of swapping plants for animals is no guarantee for a better diet. Because the devil is in the details. A person might wind up consuming more ultra-processed foods. Or they may have a hard time getting specific nutrients. Our diets are more complicated than the sound bites popular culture seems to feed us.

Beware Sweeping Generalizations

For true believers, the health benefits of avoiding animal products are unquestionable. “Vulnerable populations are better nourished by vegetables, fruits, legumes, and whole grains than by striated muscle and cow milk,” writes Neal Barnard for an AJCN debate paper.

We find a more reasonable position from Faidon Magkos and colleagues:

“A transition to more plant-based diets may exert beneficial effects on the environment, but is unlikely to affect obesity, and may also have adverse health effects if this change is made without careful consideration of the nutritional needs of the individual relative to the adequacy of the dietary intake.”

In truth, the press for more from plants and less from animals in our diets is a reasonable experiment. But we should keep eyes wide open because surprises will surely come along the way. Above all, we must be careful to find joy in what we eat. If we tell ourselves food is only medicine, well-being will surely suffer.

Click here for the paper by Salomé et al, here for more from the AJCN debate paper, and here for the perspective from Magkos et al.

Farmer Milking a Goat, painting by Ernst Ludwig Kirchner / WikiArt

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August 24, 2021