The U.S. government has updated its dietary guidelines, advising Americans to significantly increase their protein intake. The previous recommendation of 0.8 grams of protein per kilogram of body weight has been revised to between 1.2 and 1.6 grams per kilogram daily – a 50% to 100% increase. For a 154-pound person (70 kg), this means consuming 84 to 112 grams of protein daily, compared to the previous 56 grams.
Why the Change?
The reasoning behind this shift remains unclear, even to experts. Alice Lichtenstein, a nutrition scientist at Tufts University, stated in an email to Live Science, “It is unclear why the [Dietary Guidelines for Americans] increased the recommendation by 50% to 100%.” Current consumption levels already exceed the old guidelines, with studies showing U.S. adults consuming between 1.2 and 1.4 grams per kilogram daily. This raises questions about the real-world impact of the new recommendations.
The Role of Protein in the Body
Proteins are vital for building and repairing tissues, producing enzymes, hormones, and even carrying oxygen in the blood. The body breaks down dietary proteins into amino acids, nine of which are essential and must be obtained through food. Protein-rich sources include meat, fish, eggs, tofu, beans, and nuts.
Activity Level Matters
Experts agree that increasing protein intake alone won’t necessarily benefit sedentary individuals. Protein intake should align with physical activity; increases in one should be matched by increases in the other. As Lichtenstein points out, “Most of the studies that I am aware of have not demonstrated that increasing protein intake above current recommendations increases lean muscle mass.” Strength and endurance training are key to maximizing protein’s benefits.
Risks of Excess Protein
While protein is essential, excessive consumption can have drawbacks. Some studies link high-protein diets (over 1.2 to 2 grams per kg) to bone-density loss, kidney stones, and even an increased risk of heart attack or stroke due to amino acid imbalances.
Specifically, excessive leucine intake may interfere with immune cell function, while high-purine protein sources (like red meat) can exacerbate gout and kidney issues. Registered dietitian nutritionist Bridget Cassady notes that an “excessive” amount varies based on individual factors like age, weight, activity level, and health status.
Finding the Balance
Moderately high protein intake (around 2 grams per kg) is generally safe for healthy individuals as part of a balanced diet. The key is to avoid crowding out other essential nutrients like fiber, healthy fats, and whole carbohydrates.
In conclusion, the updated protein recommendations reflect a growing understanding of its role in health, but they also highlight the importance of individualized nutrition. Simply increasing protein intake without considering activity levels and overall dietary balance may not yield benefits and could even pose risks.
