How much protein do I need?

Author: 

Micaela Karlsen, MSPH

Question: 

How much protein do I really need daily?

Answer: 

Protein requirements vary slightly from individual to individual, but the average for adults is a minimum of about 4-5% protein calories of total calories per day, or 0.6g/kg body weight. This average minimum was created by scientists who measured people’s protein consumption and nitrogen balance and determined how much protein (as nitrogen) must be consumed to balance how much is routinely lost (the body is always replacing old protein).

Since minimum requirement is an average, that means half of adults needs more than that minimum, and half need less. In order to take into account the needs of people who require more than the average, the Recommended Daily Allowance (RDA) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies,  is set at 0.8g/kg body weight, or around 8-10% of total calories.

The Dietary Reference Intakes are accessible online here:

http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-tables

If you are consuming at least that much, you are almost certainly getting more than what you need. What this means is that someone eating a diet of 2,000 calories per day would need no more than 200 calories to come from protein. Fat contains 9 calories per gram, and carbohydrate and protein both contain 4 calories per gram. 200 divided by 4 = 50 grams of protein per day.

Conveniently, eating a varied whole-food, plant-based diet will naturally provide approximately 10% of protein from total calories without any special effort. While 50 grams per day is a fine average, it is not necessary to do anything in particular to achieve this, as long as you are eating whole foods. There is no need to count grams of protein or count calories. In developed countries we have the privilege of access to fresh, good quality plant foods at all times of year it is easy to get enough calories and enough protein. As long as you are consuming adequate calories from a variety of whole plant foods, you will easily meet your protein requirement.

Comments

Data from WHO

There is also the 2007 report from the World Health Organization (WHO): http://www.who.int/nutrition/publications/nutrientrequirements/WHO_TRS_9... From section 7.10, first para (bottom of page 125): "The requirement indicated by the meta-analysis (6) (a median requirement of 105 mg nitrogen/kg per day or 0.66 g/kg per day of protein) can be accepted as the best estimate of a population average requirement for healthy adults." And: "...the safe level was identified as the 97.5th percentile of the population distribution of requirement, i.e. 133 mg nitrogen/kg per day, or 0.83 g/kg per day protein. Thus 0.83 g/kg per day protein would be expected to meet the requirements of most (97.5%) of the healthy adult population." Table 46 on page 243, simply provides the math, i.e. take the weight in kilograms in the 1st column and multiply by 0.83 g/kg. For example, 70kg * 0.83 g/kg = 58g. Thus, 58g of protein will meet the needs of 97.5% of the adults that weigh 70kg (154 pounds). The USDA has set the RDA for protein at 56g for men, and 46g for women. Also, it is important that people realize that the "R" in RDA is for "recommended" - not "required". As Dr. T. Colin Campbell, and others, have rightly noted the problem is that most people in developed countries get too much protein. Dr. Campbell's research has indicated, excess animal protein (over 10% of calories) promotes cancer growth.

Re: Data from WHO

Thanks for sharing that info!

The WHO recommendations are also similar to the US RDA from the Dietary Reference Intakes - while 0.6g/kg/day (4-5% calories) from protein is the average minimum requirement, the RDA is a bit higher since it takes into account the fact that half the population needs more than the minimum. The RDA is 0.8g/kg/day, which also translates to about 8-10% calories from protein.

The Dietary Reference Intakes are accessible online here:

http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-tables

And the protein requirements are listed in the macronutrients document.