Volume 4 Number 2

 

Research Articles
79

Evening Dietary Tryptophan Improves Post-Sleep Behavioral and Brain Measures of Memory Function iIn Healthy Subjects
C. ROB MARKUS, LISA M. JONKMAN, JAN H.C.M. LAMMERS AND NICOLAAS E.P. DEUTZ[ABSTRACT]

Review Articles
89

Chromium: A Case Study in How Not To Perform Nutritional Research
DONTARIE STALLINGS AND JOHN B. VINCENT[ABSTRACT]

113

Health Issues of Whey Proteins: 1. Protection of Lean Body Mass
GERTJAN SCHAAFSMA

123

Health Issues of Whey Proteins: 2. Weight Management
GERTJAN SCHAAFSMA

Research Articles
127

Chemoprevention of Colon Carcinogenesis by Dietary Non-Nutritive Compounds
Jessica L. Franciose, E. Wayne Askew, John C. Lang, and Paul S. Bernstein[ABSTRACT]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 2, pp. 79-88 (2006)

Evening Dietary Tryptophan Improves Post-Sleep Behavioral and Brain Measures of Memory Function iIn Healthy Subjects
C. ROB MARKUS, LISA M. JONKMAN, JAN H.C.M. LAMMERS AND NICOLAAS E.P. DEUTZ

ABSTRACT: Brain serotonin function has been implicated in the control of sleep and sleep related memory dysfunctions are attributed to deficient brain serotonin activity. Depletion of the serotonin precursor tryptophan reduces brain serotonin function and is found to cause sleep abnormalities and cognitive decline. We hypothesized that enhancing pre-sleep brain tryptophan availability via a dietary increase in the ratio of plasma tryptophan to the sum of the other large neutral amino acids (Trp/LNAA) improves post-sleep memory functioning particularly in subjects with mild sleep complaints. To test whether evening intake of a tryptophan-rich diet increases the plasma Trp/LNAA ratio before sleep and improves early morning behavioral and brain measures of memory function in subjects with mild sleep complaints and controls. Twenty-eight subjects with mild sleep complaints and 28 controls participated in a double-blind placebo-controlled study. They stayed at the laboratory for an overnight sleep to monitor their post-sleep memory performance following either an evening diet containing tryptophan-rich protein or placebo protein. Evening dietary-induced changes in the plasma Trp/LNAA ratio were measured. Besides measuring behavioral changes, also task-related electroencephalographic brain activity (ERP) was measured as an index of cerebral changes in memory function. The tryptophan-rich diet caused a 130% increase in the plasma Trp/LNAA ratio (P = 0.0001) and in all subjects improved behavioral (P=0.001) and ERP (P=0.05) brain measures of memory function. Post-sleep memory function improves after pre-sleep dietary increases in plasma TRP/LNAA probably by improved sleep.

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 2, pp. 89-112 (2006)

EFFECTS AND SAFETY OF ANTIOXIDANT SUPPLEMENTATION
DONTARIE STALLINGS AND JOHN B. VINCENT

ABSTRACT: Of all the "essential" elements, the role of chromium (Cr) is undoubtedly the most controversial. Recently its status as an essential element, first proposed nearly 50 year ago, has been challenged; this challenge will probably result in the general consensus on the status changing. This change will be the result of a new generation of researchers in the field, which was dominated for the first four decades by a small group of researchers. These new researchers were attracted to the field by the rapidly expanding popular attention received by Cr nutritional supplements, which was not being mirrored by scientific advances in understanding how these supplements could work at a molecular level. The new researchers have exposed several methodological problems in earlier studies on Cr and have generated a proliferation of proposals on how Cr might affect carbohydrate and lipid metabolism in the body. Yet, each of these new potential paradigms has their own weaknesses such that a role for Cr at a molecular level is an open area for debate and continued research. At nutritionally relevant levels, chromium supplementation has no demonstrated beneficial effects on healthy humans. At the same time, recent research on animal models has convincingly demonstrated potential pharmacological uses for Cr (III) compounds if the compounds can be established to lack toxic effects. The financial implications of the pharmaceutical verses nutraceutical verses toxin debate, which underlie much of the research in the field in the last 2 decades, have made the debate quite heated. For the field to advance, whether or how Cr can function at a molecular level in beneficial and/or deleterious manners must be determined. Finally, the question as to whether an essential element can be required in such small amounts that generating deficiency in a calorie-sufficient diet is possible is discussed.

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 2, pp. 113-122 (2006)

Health Issues of Whey Proteins: 1. Protection of Lean Body Mass
GERTJAN SCHAAFSMA

ABSTRACT: Loss of muscle mass as a consequence of changes in protein metabolism during periods of catabolic stress is a serious complication in a variety of conditions. These conditions are weight loss programs, sarcopenia in the elderly and several clinical states. It appears from many studies that improved protein nutrition by ingestion of high-quality proteins can help to decrease loss of lean body mass. Essential amino acids, especially branched-chain amino acids (BCAA) and cysteine are implicated as key factors in this regard. Since whey protein is one of the best naturally occurring proteins in terms of digestibility and concentration of BCAA and cysteine, this paper reviews the significance of whey protein for protection of lean body mass. It is concluded that whey proteins will help to reduce unwanted loss of muscle mass during weight loss regimens. Ingestion of whey will contribute to an increase of muscle mass during exercise programs, designed to prevent or reduce sarcopenia in the very old. Moreover, ingestion of whey protein is useful in the prevention of muscle mass loss in (clinical) catabolic conditions. The extent to which whey protein offers a specific nutritional advantage in humans over other high-quality proteins needs to be assessed.

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 2, pp. 123-126 (2006)

Health Issues of Whey Proteins: 2. Weight Management
GERTJAN SCHAAFSMA

ABSTRACT: The increasing prevalence in many countries of people with overweight and obesity is undoubtedly one of the biggest threats to public health. Dietary proteins, because of their positive effects on satiation/satiety, may help to reduce energy intake and promote a healthy body composition with less body fat. Several mechanisms have been put forward to explain why proteins, as compared to fats and carbohydrates, enhance satiation. These are diet-induced thermogenesis, increased post-prandial concentration of plasma amino acids and effects on gut hormones, playing a role in the brain-gut axis. In this paper these mechanisms are discussed and the significance of whey proteins for weight management is evaluated. It is concluded that replacement of either fat or carbohydrates by whey proteins can be helpful in reduction of energy intake. To what extent whey proteins offer a specific advantage in this regard as compared to other dietary proteins, should be investigated in more detail.

 

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 2, pp. 127 (2006)

Chemoprevention of Colon Carcinogenesis by Dietary Non-Nutritive Compounds

TAKUJI TANAKA, SHINGO MIYAMOTO, RIKAKO SUZUKI, AND YUMIKO YASUI

ABSTRACT: Dietary habit is instrumental in about 40-60% of human colon cancer. Fruit and vegetable consumption is associated with decreased risk of several types of cancer, including colonic malignancy. Fruits and vegetables contain many non-nutritive as well as nutritive compounds, such as carotenoids, dithiolthiones, flavonoids, glucosinolates, indoles, isothiocyanates, monoterpenes, phenols, sterols, sulthydryls, and vitamins (including vitamin C, vitamin E, and folate). There may be other unknown non-nutritive constituents in foods that can reduce cancer development. Animal studies in experimental chemical carcinogenesis have indicated that several non-nutritive components, belonging to different chemical groups, in foods protect against certain types of cancer including colonic neoplasm. These chemicals are known as 'chemopreventive agents'. Many of them are anti-oxidants and might suppress carcinogenesis through (I) inhibiting phase I enzymes or blocking carcinogen formation, (ii) induction of phase II (detoxification) enzymes, (iii) scavenging DNA reactive agents, (iv) modulation in hormone homeostasis, (v) suppression of hyper-cell proliferation induced by carcinogen, (vi) induction of apoptosis, (vii) depression in tumor angiogenesis, and/or (viii) inhibition of certain phenotypic expression of neoplastic cells. With increasing the incidence of colon cancer rising certainly, there is an ever-increasing need to determine the most effective arms to prevent colon cancer and to understand the mechanism(s) underlying successful prevention. There are critical inter-relationships between diet, environment, and genetics that can affect cancer risk. Again, fruits, vegetables, teas, spices, and herbs consumed in the diet have ability of reducing cancer occurrence in pre-clinical animal carcinogenesis models. Although epidemiologic studies show similar associations, there are very few intervention studies to date. This article will introduce our recent studies in search for the effective chemopreventive effects of several naturally occurring non-nutritive products in edible plants on rat colon carcinogenesis.