The World Health Organization (WHO) and the European Food Safety Association (EFSA) sets the Safe Level of Protein (SLP) intake at 0.83 g per kilogram per day.
At ZOE, our recommendation for an optimal protein intake factors in your weight, your age and birth sex. Specifically, for healthy, younger males (females) 18-50 years old we recommend a daily intake of ≥0.8 and <1.2 g/kg (≥0.8 and <1.4 g/kg) and for older males (females) we recommend a daily intake of ≥1.0 and <1.6 g/kg BM/d (≥1.0 and <1.8 g/kg).
Why do we suggest ranges that go above the WHO's recommendation?
Our recommendations tend to allow for higher protein intakes since we favour diets high in plant sources. Most plant sources do not contain all the essential amino acids, meaning that to ensure a diet rich in plants covers all the amino acids we should be eating a wider variety of food and a higher overall protein intake is expected.
Why do we suggest an upper limit to how much protein to consume?
Most guidelines do not specify an upper limit for how much protein to eat. We have provided guidance beyond what is considered the ‘Optimal’ range for most healthy adults to indicate that a slight excess of protein will likely be inconsequential but with no added benefits.
Sustained excessive protein consumption may have negative health implications: it may lead to weight gain since the body will break down the excess protein and may convert it into fat, and increase the risk of kidney stones. In addition, if the protein intake is coming from sources high in saturated fats such as most red meat, there will be an increased risk of some diseases such as colon cancer and cardiovascular problems.
Why do we recommend different intakes for people of different ages and sex?
Older adults may benefit from eating up to twice the recommended range to support muscle growth, hence why we provide higher recommended targets. Many older adults do not consume this much protein and are likely to benefit from higher consumption. The body’s mechanism to build new muscle requires regular stimulation. Protein plays a key role in this stimulation process. As we age, the mechanisms become less efficient so higher protein intake is required to get the same response as in younger individuals (e.g., Paddon-Jones et al. 2009).
Female adults, especially older females, may benefit from higher intakes of protein. Many women, will have different dietary needs as they go through different stages in their menstrual cycle or as they enter menopause (e.g. Wohlgemuth et al. 2022, Rafii et al. 2015). While the evidence is not conclusive, we have slightly bumped protein intake for females to reflect our understanding to date.
Are these recommendations right for me?
Our recommendation is based on your weight, sex and age and is expected to meet the protein needs of most of the world’s healthy adult population. We are working to personalise further our recommendations in the app, as some people may benefit from different protein intakes, including:
Women going through menopause produce less oestrogen, which is linked to a reduction in muscle mass and bone strength (e.g., Maltais et al. 2009). Eating enough protein, together with other key nutrients like calcium and vitamin D, can help mitigate this. Early research hypothesises that hormonal changes during menopause increase our need for protein. When these needs are not met, the body may drive us to overeat other macronutrients like fat and carbohydrates which may lead to weight gain (e.g. Simpson et al. 2022).
People who have a restricted diet, which may be the case for many older adults who tend to eat fewer calories. In these cases, it is important to ensure that individuals follow a protein rich diet to ensure they reach the recommended daily targets.
Athletes undergoing intense fitness activities may benefit from consuming more than double the recommended range (see e.g. Morton et al. 2018, Jager et al. 2017).
People with kidney problems could also benefit from reducing intake slightly from the recommended range. We recommend you seek a doctor’s advice if this applies to you.
Pregnant and breastfeeding women may also benefit from higher protein intakes, see e.g. the EFSA’s guidelines.
Vegetarians and vegans must ensure they eat a wide variety of protein sources as most plant based foods do not contain all the 9 essential amino acids.
People living with obesity (e.g. BMI over 30) may need to cut back on their protein target. Our protein recommendations are based on total body mass as research indicates that individuals with a higher BMI (>30) have increased protein requirements. Some studies suggest that correction for high BMI may need to be applied, however the evidence in this area is still developing so there is no consensus on the best methods to correct protein requirements for individuals with higher BMIs.