曾焯文:動物蛋白對孕婦、胎兒的影響

Share This:
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  

pic via Jerry Lai

美國公眾健康權威米高.格加醫生(Greger, 2017)徵引近四十年來多項重要醫學研究,證明高動物蛋白飲食嚴重影響孕婦及胎兒健康,包括壓力賀爾蒙猋高、肥胖症,男人睾酮下降等,甚至禍延子孫。

「懷孕期間高蛋白飲食:健康抑或有害?」(Blumfield and Collins, 2014)四十年前,臭名昭著的一九七六年Harlem試驗回答了這個問題:〈貧窮黑人城市人口,懷孕期營養補充,隨機對照試驗〉(Rush, Stein and Susser, 1980)。「做此研究的時代假定窮人的飲食缺乏蛋白質」。如果開始試驗之前,分析其飲食,就會意識到這假設不確。但是,為何讓事實妨礙假設呢?

因此,研究人員將貧窮黑人孕婦分成三組,每日給他們額外動物蛋白質四十克 :基本為兩三罐雅培,對約六克額外動物蛋白,或無額外蛋白質,然後坐觀發生何事。高蛋白組遭逢「早產超多及相關夭折」以及「顯著生長遲緩」。越多蛋白質,越易早產,越易夭折,生長遲緩越多。

而且,根據Maslova、Rytter、Bech、et.al.(2014),母親懷孕期間攝入動物蛋白質證實同兒童長大後超重,以及,根據Shiell、Campbell-Brown、Haselden、et.al(2001),同兒童長大後高血壓相關。「多食肉同魚母親的後代」成年後血壓偏高。這是另一失敗膳食干預試驗的一部分,其中建議母親日日吃一磅肉。體重和高血壓增加可能由於肉類供應中的化學污染物引起肥胖(Shiell, Campbell-Brown, Haselden, et.al., 2001),如之前所討論的,又或由於動物蛋白誘導生長賀爾蒙IGF-1升高(Greger, 2016)。又或由於類固醇壓力賀爾蒙,皮質醇(Shiell, Campbell-Brown, Haselden, et.al., 2001)。

一餐高動物蛋白膳食足以使血糖中的壓力賀爾蒙水平在餐後半小時內加倍,遠超蛋白質接近推薦水平的膳食(Slag, Ahmed, Gannon, Mary, et.al., 1981)。食餐蟹肉、吞拿魚、芝士,壓力賀爾蒙即時猋升。相反,飲碗大麥湯,食餐蔬菜炒飯,壓力賀爾蒙即刻下降(Gibson, Checkley, Papadopoulos, 1999)。

試想,如果長年類月食肉、魚、奶類製品,壓力反應軸可能慢性受到刺激,血管活性賀爾蒙釋放可能增加,血壓可能上升。並且,額外的皮質醇釋放已顯示關乎血液中胰島素、甘油三酯和膽固醇水平上升(Gibson, Checkley, Papadopoulos, 1999)。

本來飲食高蛋白(肉、魚、家禽、蛋白)的男人,如切換到高碳水化合物飲食(麵包,蔬菜,生果及〔含糖垃圾食物〕),皮質醇水平十日內下降約四分之一。同時,其睾酮水平約同量上升。高蛋白飲食抑制睾酮。這就是何以飲食植物為本的男人,如切換到日日食肉,睾酮水平就會下降,有些雌賀爾蒙甚至上升(Anderson, Rosner, Khan, et.al. ,1987)。

這就是何以健美運動員睾酮水平可以如此低,根本不關其所服類固醇的事(Woodhill, Cooper, Zacharin, 2014)。不服類固醇的自然健美運動員, 在比賽前十二個月內,睾酮水平下降百分之七十。睾酮水平減少一半以上;足以令個大男人陷入低潮。諷刺的是,他們食動物蛋白質,外表好似「好man」,但內裡則越來越「娘」(Rossow, Fukuda, Fahs, 2013)。而且,一般而言,睾酮水平下降可能導致體重增加:體脂增加(Khaw and Barret-Connor, 1992)。

皮質醇與體重有何關係?其實有一病源於皮質醇過多,稱為古成氏綜合症 (Peeke, and Chrousos, 1995)。而且,事前事後大肚腩。即使正常婦女,慢性壓力,慢性高皮質醇水平 ,都可以導致肥胖(Vicennati, Pasqui, Cavazzu, et.al. , 2009)。如果懷孕,多肉低碳水化合物飲食可能增加母體皮質醇水平,這可能令胎兒不當暴露於皮質醇,反過來,可影響發展中的胎兒,重置其成個壓力 – 反應恆溫器,導致皮質醇水平成世偏高,嚴重的健康後果可能伴隨一生(Herrick, Philips, Haselden, et.al., 2003)。

這正是研究人員所發現的。母親日食一份肉和魚,證實關乎子女長達三十年皮質醇偏高五巴仙,不過食綠色蔬菜發現具保護作用。食更大量的肉和魚,例如日日三份,相比一到兩份 ,證實關乎皮質醇水平顯著更高。但是,日食綠色蔬菜似乎能減輕這種過度的壓力反應(Herrick, Philips, Haselden, et.al., 2003)。

而且,懷孕期間食大量肉類的母親的成年子女不僅壓力賀爾蒙水平偏高(Herrick, Philips, Haselden, et.al., 2003),而且似乎對任何生活衝擊的反應偏向負面。如果在其身上實行特里爾測試(Trier Test):包括在班評判前公開演講,繼之以現場數學練習,日食兩三份肉的母親子女口水皮質醇遠高於日食不到兩份肉的母親子女與日食兩份肉的母親子女。日食不到兩份肉的母親子女與日食兩份肉的母親子女,在測試開始前反應差不多,但一旦暴露於緊張的情況,皮質醇反應的分別就相當明顯(Reynolds, Godfrey, Barker, et.al. , 2007)。

現在,經過以上測試後,如提供兩種小食:生果蔬菜,對比脂肪甜食,例如朱古力蛋糕,估下誰會少食生果蔬菜?就是那些壓力水平慢性偏高的人。即使並非真餓,皮質醇都會刺激食物攝取(Tryon, Decant, Laugero, et.al., 2013)。

故此,毫不奇怪,懷孕期間攝入動物蛋白可能導致子女,甚至孫兒,日後體重偏高(Maslova, Rytter, Bech, et.al., 2014)。壓力軸的確可以受影響到如斯地步。最新證據表明,長期不良後果「可能不限於一代人...懷孕母親的飲食可能會影響子女甚至孫兒的發展和患病風險...最終,這些發現〔可能〕令世人更明瞭〔迅速擴大的時疫〕糖尿病、肥胖症和〔心臟病〕。」(Roseboom and Watson, 2012)

參考書目

Anderson, Karl; Rosner, William; Khan, M.S., et.al. (1987) . “Diet-hormone interaction: Protein/carbohydrate ratio alters reciprocally the plasma levels of testosterone and cortisol and their respective binding globulns in man,” Life Sciences 40(18):1761-8, June.

Blumfield, Michelle; Collins, Clare (2014). “High protein diets during pregnancy: healthful or harmful for offspring?” Am J Clin Nutr 100:993-5.

Gibson, Leigh; Checkley, Stuart; Papadopoulos, Andrew, et.al. (1999). “Increased salivary cortisol reliably induced by a protein-rich midday meal,” Psychosomatic Medicine 61: 214-224.

Greger, Michael (2016). “Animal protein, pregnancy, and childhood obesity,” NutritionFact.org, Volume 32, October 28.

Greger, Michael (2017). “The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy ,” youtube, Jan. 18. https://www.youtube.com/watch?v=kXty_-3o7X8
Herrick, Kirsten; Philips, David; Haselden, Soraya, et.al. (2003). “Maternal consumption of a high-meat, low-carbohydrate diet in late pregnancy: Relation to adult cortisol concentrations in the offspring,” J Clin Endocrinol Metab. Aug;88(8):3554-60.

Khaw, Kay-Tee; Barret-Connor, Elizabeth (1992). “Lower endogenous androgens predict central adiposity in Men,” Ann Epidemiol 2: 675-682.

Maslova, Ekaterina; Rytter, Dorte; Bech, Bodil, et.al. (1995). “Maternal protein intake during pregnancy and offspring overweight 20 y later,” Am J Clin Nutr 100:1139-48.

Peeke, Pamela; Chrousos, George (1995). “Hypercortisolism and obesity,” Ann N Y Acad Sci 1995 Dec 29; 771: 665-76.

Reynolds, Rebecca; Godfrey, Keith; Barker, Mary, et.al. (2007). “Stress responsiveness in adult life: Influence of mother’s diet in late pregnancy,” J Clin Endocrinol Metab. Jun; 92(6): 2208-10.

Roseboom, T.J.; Watson, E.D. (2012). ” The next generation of disease risk: are the effects of prenatal nutrition transmitted across generations? Evidence from animal and human studies,” Placenta. Nov; 33 Suppl 2: e40-4.

Rossow, Lindy; Fukuda, David; Fahs, Christopher (2013). “Natural bodybuilding competition preparation and recovery: A 12-month case study,” International Journal of Sports Physiology and Performance, 8: 582-592.

Rush, David; Stein, Zena; Susser, Mervyn (2001). “A randomized controlled trial of prenatal nutritional supplementation in New York City,” PEDIATRICS Vol. 65 No. 4 April.

Shiell, Alistair; Campbell-Brown, Mary; Haselden, Soraya, et.al. “High-meat, low-carbohydrate diet in pregnancy: Relation to adult blood pressure in the offspring,” Hypertension, 38: 1282-1288.

Slag, Michael; Ahmed, Mohammed; Gannon, Mary, et.al. (1981). “Meal stimulation of cortisol secretion: A protein induced effect,” Metabolism, Vol. 30, No.11 (November).

Tryon, M.S.; Decant, Rashel; Laugero, K.D., et.al. (2013). “Having your cake and eating it too: A habit of comfort food may link chronic social stress exposure and acute stress-induced cortisol hyporesponsiveness,” Physiology and Behavior 114-115: 32-37.

Vicennati, Valentina; Pasqui, Francesca; Cavazzu, Carla, et.al. (2009). “Stress-related development of obesity and cortisol in women,” Obesity 17: 1678-1683.

Woodhill, Ineke; Cooper, Chris; Zacharin, Margaret (2014). “Low testosterone in a male adolescent bodybuilder: Which diagnosis holds more weight?” Journal of Pediatrics and Child Health 50: 739-741.


Share This:
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  

Comments