The effect of a plant-based diet on plasma lipids in hypercholesterolemic adults: a randomized trial.

BACKGROUND: A variety of food combinations can be used to meet national U.S. guidelines for obtaining 30% of energy or less from total fat and 10% of energy or less from saturated fat. OBJECTIVE: To contrast plasma lipid responses to 2 low-fat diet patterns. DESIGN: Randomized clinical trial. SETTING: 4-week outpatient feeding study with weight held constant. PARTICIPANTS: 120 adults 30 to 65 years of age with prestudy low-density lipoprotein (LDL) cholesterol concentrations of 3.3 to 4.8 mmol/L (130 to 190 mg/dL), body mass index less than 31 kg/m2, estimated dietary saturated fat at least 10% of calories, and otherwise general good health. MEASUREMENTS: Plasma lipid levels. INTERVENTION: Two diets, the Low-Fat diet and the Low-Fat Plus diet, designed to be identical in total fat, saturated fat, protein, carbohydrate, and cholesterol content, consistent with former American Heart Association Step I guidelines. The Low-Fat diet was relatively typical of a low-fat U.S. diet. The Low-Fat Plus diet incorporated considerably more vegetables, legumes, and whole grains, consistent with the 2000 American Heart Association revised guidelines. RESULTS: Four-week changes in the Low-Fat and Low-Fat Plus groups were -0.24 mmol/L (-9.2 mg/dL) versus -0.46 mmol/L (-17.6 mg/dL) for total cholesterol (P = 0.01) and -0.18 mmol/L (-7.0 mg/dL) versus -0.36 mmol/L (-13.8 mg/dL) for LDL cholesterol (P = 0.02); between-group differences were -0.22 mmol/L (-9 mg/dL) (95% CI, -0.05 to -0.39 mmol/L [-2 to -15 mg/dL]) and -0.18 mmol/L (-7 mg/dL) (CI, -0.04 to -0.32 mmol/L [-2 to -12 mg/dL]) for total and LDL cholesterol, respectively. The 2 diet groups did not differ significantly in high-density lipoprotein cholesterol and triglyceride levels. LIMITATIONS: 4-week duration. CONCLUSIONS: Previous national dietary guidelines primarily emphasized avoiding saturated fat and cholesterol; as a result, the guidelines probably underestimated the potential LDL cholesterol-lowering effect of diet. In this study, emphasis on including nutrient-dense plant-based foods, consistent with recently revised national guidelines, increased the total and LDL cholesterol-lowering effect of a low-fat diet.

Effect of tartaric acid and dietary fibre from sun-dried raisins on colonic function and on bile acid and volatile fatty acid excretion in healthy adults.

Sun-dried raisins are a source of dietary fibre and tartaric acid. The effects of tartaric acid on colon function have not been the focus of extensive research. The purpose of the present study was to evaluate the effects of dietary fibre and tartaric acid from sun-dried raisins on colon function and on faecal bile acid and short-chain fatty acid (SCFA) excretion in healthy adults. Thirteen healthy subjects were fed 120 g sun-dried raisins/d or 5 g cream of tartar (equivalent to the tartaric acid in 120 g sun-dried raisins)/d for 9 weeks, divided into 3-week cycles. The experimental diets were fed in a crossover design after an initial control period. Faeces were collected for the last 4 d of each cycle for analysis of SCFA and bile acids. Intestinal transit time decreased from 42 h on the baseline diet to 31 h on cream of tartar (P<0.1) and to 28 h on sun-dried raisins (P<0.05). Faeces were softer on both sun-dried raisins and cream of tartar, but sun-dried raisins increased faecal wet weight (P<0.05), while cream of tartar did not. Sun-dried raisins caused significant reductions from baseline values in total bile acid concentration (from 1.42 (SD 1.03) to 1.09 (SD 0.76) mg/g, P<0.05), whereas cream of tartar did not (1.40 (SD 1.06) mg/g). Sun-dried raisins also significantly reduced the lithocholic (LC):deoxylithocholic acid (DC) ratio (from 1.63 (SD 0.85) to 1.09 (SD 0.50), P<0.02), whereas cream of tartar reduced the ratio, but to a lesser extent (1.29 (SD 0.79), NS). Both faecal bile acids and the LC:DC ratio are indicators of reduced risk for colon cancer. Sun-dried raisins increased total SCFA excretion (from 5.6 (SD 3.4) to 7.6 (SD 3.0) g/4 d, P<0.05), which remained unchanged with cream of tartar (5.6 (SD 3.0) g/4 d). Both sun-dried raisins and cream of tartar appear to be good stool softeners and to shorten intestinal transit time, although the fibre in sun-dried raisins has the added benefit of increasing faecal weight. Both sun-dried raisins and cream of tartar modulate the composition of faecal bile acids and SCFA in a way that has potential health benefits.

Effect of sun-dried raisins on bile acid excretion, intestinal transit time, and fecal weight: a dose-response study.

The effect of increasing doses of sun-dried raisins (SDR) on intestinal transit time (TT), fecal weight (FW), and fecal bile acids (FBA) was investigated in 16 healthy adults (6 men and 10 women). In three cycles of 2 weeks each, subjects consumed 84, 126, or 168 g/day of SDR. Four-day fecal collections were performed during the second week of each cycle, and TT, FW, and FBA were measured. FW (mean +/- SEM), increased from 168 +/- 14 g/day without raisins (cycle 1), with a TT of 54 +/- 6 hours, to 200 +/- 24 g/day with 168 g/day raisins (cycle 4), with a TT of 42 +/- 6 hours. Intermediate increases in FW and decreases in TT were observed for cycles 2 and 3. A physiologically meaningful decrease in TT (less than 2 days), to 44 +/- 6 hours, was reached at cycle 2 (not statistically significant). FBA, a possible indicator of colon cancer risk, showed a significant decrease, from 1.00 +/- 0.18 mg/g wet feces at baseline to 0.38 +/- 0.07 mg/g in cycle 2 (P <.005), and remained low in cycles 3 and 4. Major decreases were observed in cycle 2 for fecal lithocholic (P <.02), deoxycholic (P <.002), chenodeoxycholic, and cholic acids, and their concentrations remained low in cycles 3 and 4. Two servings of raisins per day (84 g/day), a relatively small change in diet, can cause beneficial changes in colon function and may decrease the risk for colon cancer.

Safety of an astaxanthin-rich Haematococcus pluvialis algal extract: a randomized clinical trial.

A growing body of scientific literature indicates that astaxanthin is a more powerful antioxidant than other carotenoids and vitamin E and may confer numerous health benefits. The purpose of this investigation was to conduct a human safety study with a Haematococcus pluvialis algal extract with high levels of astaxanthin. Thirty-five healthy adults age 35-69 years were enrolled in a randomized, double-blind, placebo-controlled trial of 8 weeks' duration. All participants took three gelcaps per day, one at each meal. Nineteen participants received gelcaps with an algal extract in safflower oil, containing 2 mg of astaxanthin each (treatment); 16 participants received gelcaps containing safflower oil only (placebo). Blood pressure and blood chemistry tests, including a comprehensive metabolic panel and cell blood count, were conducted at the beginning of the trial and after 4 and 8 weeks of supplementation. No significant differences were detected between the treatment and the placebo groups after 8 weeks of supplementation with the algal extract in the parameters analyzed, except for serum calcium, total protein, and eosinophils (P <.01). Although the differences in these three parameters were statistically significant, they were very small and are of no clinical importance. These results reveal that 6 mg of astaxanthin per day from a H. pluvialis algal extract can be safely consumed by healthy adults.

Effects of plant-based diets high in raw or roasted almonds, or roasted almond butter on serum lipoproteins in humans.

OBJECTIVE: To compare the lipid-altering effect of roasted salted almonds and roasted almond butter with that of raw almonds, as part of a plant-based diet. METHODS: Thirty-eight free-living, hypercholesterolemic men (n = 12) and women (n = 26) with a mean total serum cholesterol (TC) of 245 + 29 mg/dL (mean + SD) followed a heart-healthy diet including 100g of one of three forms of almonds: roasted salted almonds, roasted almond butter or raw almonds for four weeks. Measurements of serum TC, triglycerides (TG), selected lipoproteins and blood pressure were taken at baseline and after four weeks. RESULTS: All three forms of almonds in the context of a heart-healthy diet significantly lowered low-density lipoprotein-cholesterol (LDL) from baseline to the completion of the study. Both raw and roasted almonds significantly lowered TC, whereas the decrease by almond butter (in a smaller cohort) did not reach statistical significance. High-density lipoprotein-cholesterol (HDL) did not significantly change with raw or roasted almonds but slightly increased with almond butter. At the end of the study, blood pressure did not change significantly from baseline values for any of the groups. CONCLUSION: These results suggest that unblanched almonds-whether raw, dry roasted, or in roasted butter form-can play an effective role in cholesterol-lowering, plant-based diets.

Isoflavone supplements do not affect thyroid function in iodine-replete postmenopausal women.

Despite the safety review conducted by the U.S. Food and Drug Administration in the process of awarding a health claim for the cholesterol-lowering properties of soy protein, concerns about the possible goitrogenic effects of soybean isoflavones persist. Concerns are based primarily on in vitro research, animal studies, and older reports of goiter in infants fed soy formula not fortified with iodine. In a randomized, double blind, placebo-controlled study, we investigated the effect on thyroid function of a daily supplement containing 90 mg (aglycone weight) of total isoflavones/day versus placebo in 38 postmenopausal women, 64-83 years old, not on hormone replacement therapy. Serum thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) were measured at baseline and after 90 and 180 days. In the supplement group, at baseline and 6 months, TSH (micro U/ml), T4 (nM), and T3 (nM) levels (mean +/- SE) were 3.00 +/- 0.44, 149.00 +/- 5.04, and 1.53 +/- 0.13, respectively, and 3.49 +/- 0.52, 154.52 +/- 2.09, and 1.78 +/- 0.12, respectively. In the control group, levels at baseline and at 6 months were 3.35 +/- 0.51, 145.39 +/- 6.69, and 1.55 +/- 0.18, respectively, and 3.63 +/- 0.57, 153.77 +/- 6.64, and 1.75 +/- 0.10, respectively. Intragroup differences for all three measures were statistically indistinguishable at 6 months, and levels were similar between the isoflavone supplement and placebo groups at each measurement. These results indicate that in this group of healthy iodine-replete subjects, soy isoflavones do not adversely affect thyroid function.

Dose response of almonds on coronary heart disease risk factors: blood lipids, oxidized low-density lipoproteins, lipoprotein(a), homocysteine, and pulmonary nitric oxide: a randomized, controlled, crossover trial.

BACKGROUND: Although recent studies have indicated that nut consumption may improve levels of blood lipids, nuts are not generally recommended as snacks for hyperlipidemic subjects because of their high fat content. Furthermore, the effective dose is still unknown. METHODS AND RESULTS: The dose-response effects of whole almonds, taken as snacks, were compared with low-saturated fat (<5% energy) whole-wheat muffins (control) in the therapeutic diets of hyperlipidemic subjects. In a randomized crossover study, 27 hyperlipidemic men and women consumed 3 isoenergetic (mean 423 kcal/d) supplements each for 1 month. Supplements provided 22.2% of energy and consisted of full-dose almonds (73+/-3 g/d), half-dose almonds plus half-dose muffins, and full-dose muffins. Fasting blood, expired air, blood pressure, and body weight measurements were obtained at weeks 0, 2, and 4. Mean body weights differed <300 g between treatments. The full-dose almonds produced the greatest reduction in levels of blood lipids. Significant reductions from baseline were seen on both half- and full-dose almonds for LDL cholesterol (4.4+/-1.7%, P=0.018, and 9.4+/-1.9%, P<0.001, respectively) and LDL:HDL cholesterol (7.8+/-2.2%, P=0.001, and 12.0+/-2.1%, P<0.001, respectively) and on full-dose almonds alone for lipoprotein(a) (7.8+/-3.5%, P=0.034) and oxidized LDL concentrations (14.0+/-3.8%, P<0.001), with no significant reductions on the control diet. No difference was seen in pulmonary nitric oxide between treatments. CONCLUSIONS: Almonds used as snacks in the diets of hyperlipidemic subjects significantly reduce coronary heart disease risk factors, probably in part because of the nonfat (protein and fiber) and monounsaturated fatty acid components of the nut.

Long-term effects of nutrient intervention on markers of bone remodeling and calciotropic hormones in late-postmenopausal women.

BACKGROUND: Adequate intakes of calcium and vitamin D reduce bone loss and fracture risk in the elderly. Other nutrients also affect bone health, and adequate intakes may influence bone turnover and balance. OBJECTIVE: We compared the long-term effects on bone turnover markers and calciotropic hormones of a multinutrient supplement, a calcium and vitamin D supplement, and dietary instruction aimed at increasing calcium intake through foods. DESIGN: Ninety-nine healthy postmenopausal women participated in a 3-y, randomized trial, receiving either 1) supplemental calcium (1450 mg/d) and vitamin D [10 microg (400 IU)/d], 2) calcium, vitamin D, and other nutrients (multinutrient supplement), or 3) dietary instruction (dietary control group). Data are from 83 subjects who completed the trial. RESULTS: Increases over baseline in calcium intakes and serum 25-hydroxyvitamin D concentrations were sustained over 3 y in all treatment groups. Circulating parathyroid hormone concentrations were reduced at year 1 in all treatment groups but trended toward baseline thereafter. Bone turnover markers followed a similar pattern, and none of the changes in biochemical concentrations differed significantly between groups. CONCLUSIONS: All 3 interventions offer long-term feasibility for increasing calcium intake and serum 25-hydroxyvitamin D concentrations. The dietary addition of micronutrients implicated in skeletal physiology confers no obvious bone-sparing effect in healthy postmenopausal women beyond that of calcium and vitamin D alone. The attenuation over time in suppression of parathyroid hormone and bone turnover might help explain why nutrient intervention tends to have less of a bone-sparing effect than do skeletally active medications such as estrogen or bisphosphonates.

Effects of a very low-fat, vegan diet in subjects with rheumatoid arthritis.

OBJECTIVE: To demonstrate the effects of a very low-fat, vegan diet on patients with rheumatoid arthritis (RA). DESIGN: Single-blind dietary intervention study. SUBJECTS AND STUDY INTERVENTIONS: This study evaluated the influence of a 4-week, very low-fat (approximately 10%), vegan diet on 24 free-living subjects with RA, average age, 56 +/- 11 years old. OUTCOME MEASUREMENTS: Prestudy and poststudy assessment of RA symptomatology was performed by a rheumatologist blind to the study design. Biochemical measures and 4-day diet data were also collected. Subjects met weekly for diet instruction, compliance monitoring, and progress assessments. RESULTS: There were significant (p < 0.001) decreases in fat (69%), protein (24%), and energy (22%), and a significant increase in carbohydrate (55%) intake. All measures of RA symptomatology decreased significantly (p < 0.05), except for duration of morning stiffness (p > 0.05). Weight also decreased significantly (p < 0.001). At 4 weeks, C-reactive protein decreased 16% (ns, p > 0.05), RA factor decreased 10% (ns, p > 0.05), while erythrocyte sedimentation rate was unchanged (p > 0.05). CONCLUSION: This study showed that patients with moderate-to-severe RA, who switch to a very low-fat, vegan diet can experience significant reductions in RA symptoms.