Table 1

Protein

MacronutrientSource and qualitySummary
ProteinAnimal and plant
Lean animal protein (defined by O'Connor et al 9) as <10 g total fat, <5 g saturated fat and <95 mg cholesterol/100 g) is a better choice than fattier types
Sources of animal protein include fish, poultry, meat, eggs and dairy. Processed meat is also included in this category as a source of protein
Sources of plant protein include nuts and seeds (almonds, walnuts, cashews), pulses (including chickpeas, lentils, bean)
Animal proteins are complete (contain the nine essential amino acids) whereas plant proteins do not. This has often led to plant protein being described as low quality
Higher intakes post-MI associated with more rapid decline in renal function and increased mortality.7 8 This was more pronounced with protein derived from meat and less so with protein from dairy, fish, eggs or plant protein7 8
Comorbidities such as diabetes are associated with a greater strength of association between higher animal protein intake and the decline in renal function,7 in addition to all-cause mortality8
Protein quality (considering total and saturated fat, and cholesterol) is likely an important factor to consider. The addition of lean 500 g/week of lean (<10 g total fat, <5 g saturated fat and <95 mg cholesterol), unprocessed beef or pork (equating to approximately 71 g/day) to a cardioprotective diet did not increase cardiovascular risk and improved 10-year cardiovascular risk score when compared with the same cardioprotective diet but with only 200 g/week or lean red meat9
The comparator diet is important when examining the relationship between protein and CVD.10 When analysed against plant protein, red meat yielded smaller decreases in TC and LDL-C, but when compared with low-quality carbohydrates or fish, yielded greater decreases in LDL-C and triglycerides.
Variation in the definition of ‘meat’ could explain discrepancies in the literature. Some foods listed under meat include ‘sausage, hamburger and bacon’ which have a markedly different nutrient profile to beef, lamb and chicken7 and hence different relationship with cardiovascular health11
Protein is vital for muscle development and strength. Higher protein intakes of 1.5 g/kg/d in an elderly population improve appendicular muscle mass, the ratio of appendicular muscle to fat and increase gate speed comparison to lower protein intakes (0.8 g/kg/d). The protein used was predominantly from whey (high in leucine) which provides the stimulus for muscle growth, and no adverse outcomes were reported12
Protein is an essential macronutrient and we suggest this should be obtained from a range of plant and animal sources. Those with established renal disease should be particularly mindful of protein intake. Good quality, low fat/low saturated fat/low cholesterol sources of protein should be encouraged as part of a cardioprotective diet
  • CVD, cardiovascular disease; LDL-C, low-density lipoproten-cholesterol; MI, myocardial infarction; TC, total cholesterol.