Protein content in the diet— more, or less??
Increased protein content in foods and drinks seems to be popping up everywhere! I’ve seen an increase in protein powder types being sold at the grocery store, as well as more protein drinks, protein-enriched coffees and cereals, and I’ve even seen a “high protein” pre-mixed salad being promoted at the store recently! This approach has most certainly been supported and promoted by the “Dietary Guidelines for Americans, 2025-2030” which has literally inverted the old food pyramid that many of us learned about when we were younger. Now, instead of having meat at the narrow top of the pyramid (implying small quantities in the diet), protein is now the widest part of the pyramid (still at the top), implying the largest quantities, along with vegetables and fruits, with the guidelines specifically stating, “Prioritize Protein Foods at Every Meal.”
An excellent review and critique of the new guidelines, published in The Journal of Nutrition, emphasizes that the new dietary recommendations stem, in large part, from a rapid systematic review of randomized controlled trials focused on weight-management outcomes, as well as a review of nutrient adequacy. The authors of the review also highlight that the guidelines insufficiently address protein intake in relation to diet-related chronic diseases, like cardiovascular disease, type 2 diabetes, chronic kidney disease, cancer, and bone disease. Excessive protein intake can worsen chronic kidney disease, and is also a problem for patients with chronic liver disease, as they are unable to process the excess ammonia that is a byproduct of protein metabolism.
The amount of protein advised in the new guidelines equates to 1.2 - 1.6 g/kg/d (so for a 70 kilogram individual this would be approximately 84 - 112 grams of protein per day), which is a substantial increase from the prior recommended daily allowance of 0.8 grams per kg of body weight. This amount may be difficult to achieve, considering the following protein amounts in some common foods:
Fish or chicken: 22-25 gm per 3 oz
Yogurt: 17 gm per 6 oz
Egg: 6 gm per egg
Milk: 8 gm per cup
Tofu: 15 gm per quarter block
Black beans: 15 gm per cooked cup
Adding complexity to this issue is the fact that a recent review of the medical literature found that dietary protein restriction promotes metabolic health, healthspan, and lifespan across diverse organisms! Though the authors do admit that there might be specific amino acids at play here (specifically methionine, isoleucine and valine), providing a more nuanced approach to protein intake.
Further confusion is created when “NIH Research Matters” produces an article titled, “Protein Consumption Linked to Longevity” where literally the very first paragraph states, “A high-protein diet during middle age was associated with higher mortality in a new study. In adults over 65, however, a high-protein diet was linked to lower mortality.” Concerningly, the article further goes on to state, “Adults in the 50 to 65 group who reported a high protein intake had a 75% increase in overall mortality and were 4 times more likely to die from cancer during the following 18 years than those in the low protein group.” The article also provides the very interesting caveat: “However, the associations were only found when the proteins were derived from animal, rather than plant, sources.”
The protein intake debate requires much more research and clarification, and I will continue to write about this important topic, particularly when new articles are published. For now, my recommendations from doing extensive reading on the topic:
We know that muscle growth requires amino acids to produce proteins, so protein intake is essential, particularly for those trying to grow muscle, and in those who are physically active. Setting a goal of 1 gm/kg/day of protein is a good and reasonable target, until more clarity is obtained.
Try to obtain most of your protein from plant-based sources. Quinoa, soy, chia, buckwheat and spirulina are excellent sources.
I go into much more detail about this vital topic in my book Optimized.
