MooScience: the science of milk

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Alpha-Lactalbumin (α-Lactalbumin or α-LA)

Alpha-lactalbumin may improve mood, increase metabolism after meals, improve memory, prevent diabetes and fight cancer. Alpha-lactalbumin is a bioactive milk protein found in acid whey. Whey protein typically contains 20-25% α-LA.

It is also found in other dairy products. Cow milk contains approximately 284 mg α-LA in 1 cup (Yamaguchi and Takai 2014).

Alpha-lactalbumin is rich in cysteine, an amino acid used to make glutathione. Glutathione is a strong antioxidant which helps increase immunity.

Alpha-lactalbumin increases calorie burn after meals

Picture: "Mom says if I drink lots of milk it will help me grow up healthy and smart!" MooScience: Calves need healthy milk to grow strong.

 

Alpha-lactalbumin may elevate mood and improve sleep

Simple explanation: Eating foods with α-LA can improve mood, enhance thinking abilities and increase the chances of restful sleep. Alpha-lactalbumin does this by raising serotonin concentrations in the body. Serotonin is an important neurotransmitter that helps regulates mood, learning abilities, sleep and appetite.

Scientific explanation: When α-LA is broken down (hydrolyzed) by the body it releases cysteine and tryptophan, two essential amino acids. Essential amino acids must be obtained in foods since they can't be produced by the body. Alpha-lactalbumin contains 6% tryptophan, which makes it the best food source of this important amino acid (Heine et al. 1996).

Tryptophan is is necessary for serotonin production (serotonin is also known to its friends as 5-hydroxytryptamine or 5-HT for short). Serotonin is a neurotransmitter which also reduces appetite and suppresses pain perception. It is involved in many functions including mood, behavior, appetite, bone metabolism, aging, wound healing, endocrine regulation, sleep, memory, learning, temperature, muscle contractions and cardiovascular functions. Depression is associated with lower concentrations of brain serotonin.

Consumption of α-LA has been shown to increase tryptophan (Markus et al. 2000, Markus et al. 2005). As levels of tryptophan rise it increases the blood plasma level of tryptophan compared to other large neutral amino acids (Trp-LNAA ratio). As a result more tryptophan is transported across the blood brain barrier. Elevated concentrations of tryptophan in the brain result in enhanced serotonin synthesis.

Consuming α-LA raises serotonin concentrations which benefits mood, enhances cognitive function and improves sleep abnormalities (Markus et al. 2000, Markus et al. 2002). In one study, people who consumed α-LA in the evening showed more alertness in the mornings due to enhanced sleep (Markus et al. 2005).

 

Alpha-lactalbumin may improve memory

Depressed and non-depressed people given a one-day diet of alpha-lactalbumin enriched meals showed improved abstract visual memory compared to when the same people consumed a one-day diet rich in casein (Booij et al. 2006). There was no change in mood between the two one-day days. One day is most likely not long enough to examine the effects of α-LA on mood.

 

Alpha-lactalbumin increases endogenous antioxidants

When α-LA is broken down (hydrolyzed) by the body it releases cysteine. Cysteine is a precursor to glutathione (GSH), a vital internal antioxidant.

 

Alpha-lactalbumin improves glucose tolerance in rats and humans

Rats fed α-LA (300 mg/kg, 2x day) for 10 weeks had significantly improved glucose tolerance compared to rats not given α-LA. This may be due to increased concentrations of adiponectin (Yamaquchi and Takai 2014). Adiponectin is a hormone expressed by adipose (fat) tissue which can influence insulin sensitivity.

Higher adiponectin concentrations reduce the risk of type 2 diabetes in humans. Fasting adiponectin concentrations correlate with insulin sensitivity in Pima Indians and Caucasians (Weyer et al. 2001). Adiponectin may regulate skeletal muscle insulin receptor tyrosine phosphorylation to increase insulin sensitivity (Stefan et al. 2002).

 

Alpha-lactalbumin may inhibit cancer cells

Alpha-lactalbumin inhibits human colon cancer cells and human breast cancer cells (Sternhagen and Allen 2001, Thompson et al. 1992).

 

What is a bioactive compound?

a) A compound that glows in the dark.

b) A non-nutritional substance or compound in food that has a direct effect on a living organism. Bioactive compounds have actions in the body that may promote good health.

The answer is b! Bioactive compounds normally occur in small amounts in foods. Some bioactive compounds that you may have heard of include flavonoids, resveratrol, tannins and lycopene. Whey contains bioactive compounds, like alpha-lactalbumin, that can enhance health.

Why is alpha-lactalbumin a bioactive compound?

Alpha-lactalbumin has a direct effect on the body. It increases production of serotonin and glutathione, a vital antioxidant. Untrained rats given alpha-lactalbumin have a significant increase in liver glutathione after strenuous exercise (Mariotti et al. 2004).

 

References:

  • Booij L, Merens W, Markus CR, Van der Does AJ. J Psychopharmacol. Diet rich in alpha-lactalbumin improves memory in unmedicated recovered depressed patients and matched controls. J Psychopharmacol. 2006 Jul;20(4):526-35. Pubmed. Related full paper.
  • Heine W, Radke M, Wutzke K, Peters E, Kundt G. Lactalbumin enriched low-protein infant formulas: a comparison to breast milk feeding. Acta Paediatrica. 1996;85:1024–1028. Pubmed. doi: 10.1111/j.1651-2227.1996.tb14210.x
  • Mariotti F, Simbelie KL, Makarios-Lahham L, Huneau JF, Laplaize B, Tomé D, Even PC. Acute ingestion of dietary proteins improves post-exercise liver glutathione in rats in a dose-dependent relationship with their cysteine content. J Nutr. 2004;134:128-31. Pubmed.
  • Markus C, Jonkman L, Lammers J, Deutz NEP, Messer MH, Rigtering N. Evening intake of alpha-lactalbumin increases plasma tryptophan availability and improves morning alertness and brain measures of attention. Am J Clin Nutr. 2005;81:1026–1033. Full text.
  • Markus C, Olivier B, Panhuysen G, Van Der Gugten J, Alles MS, Tuiten A, Westenberg HG, Fekkes D, Koppeschaar HF, de Haan EE. The bovine protein alpha-lactalbumin increases the plasma Trp/LNAA ratio, and in vulnerable subjects raises brain serotonin activity and decreases cortisol and mood under stress. Am J Clin Nutr. 2000;71:1536–1544. Full text.
  • Markus CR, Olivier B, De Haan EHF. Whey protein rich in alpha-lactalbumin increases the ratio of plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive performance in stress vulnerable subjects. Am J Clin Nutr 2002;75:1051–1056. Full text.
  • Stefan N1, Vozarova B, Funahashi T, Matsuzawa Y, Weyer C, Lindsay RS, Youngren JF, Havel PJ, Pratley RE, Bogardus C, Tataranni PA. Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans. Diabetes. 2002;51:1884-8. Pubmed. Full text.
  • Sternhagen LG, Allen JC. Growth rates of a human colon adenocarcinoma cell line are regulated by the milk protein α-lactalbumin. Adv Exp Med Biol. 2001;501:115–120. Pubmed.
  • Thompson MP, Farrell HM, Mohanam S, Liu S, Kidwell WR, Bansal MP, Cook RG, Kotts CE, Bano M. Identification of human milk α-lactalbumin as a cell growth inhibitor. Protoplasma. 1992;167:134–144. Springerlink.
  • Weyer C, Funahashi T, Tanaka S, Hotta K, Matsuzawa Y, Pratley RE, Tataranni PA. Hypoadiponectinemia in obesity and type 2 diabetes: close association with insulin resistance and hyperinsulinemia. J. Clin. Endocrinol. Metab. 2001;86:1930–1935. Pubmed.
  • Yamaguchi M, Takai S. Chronic administration of bovine milk-derived α-lactalbumin improves glucose tolerance via enhancement of adiponectin in Goto-Kakizaki rats with type 2 diabetes. Biol Pharm Bull. 2014;37:404-8. Pubmed. Full text.